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The rapid development of new energy vehicles demands significant improvements in connector structures and performance standards. Wire harness connectors, crucial for linking various electrical components, face challenges due to their small size and thin-walled structure, which can lead to dimensional shrinkage and warping during injection molding. To address these issues, this study optimizes the injection molding process by fine-tuning parameters such as melt temperature, mold temperature, injection time, holding pressure/time, and cooling time. By integrating the Taguchi method with grey relational analysis, the study enhances the molding process for thin-walled composite connectors. This combined approach provides a comprehensive framework for optimizing multiple quality objectives and improving the overall performance of injection-molded composite components.

The transport of solid-liquid two-phase flow is widely used in water conservancy, environmental protection, and municipal engineering. Accurate pressure loss calculation is crucial for hydraulic transport pipelines, particularly in the case of bends, valves, and other deformation parts. These factors directly impact the energy consumption and the investment of the system. This paper employed the Euler-Euler multiphase flow model to investigate the characteristics of solid-liquid two-phase flow in vertically positioned combined elbows. The model was initially validated using data from the literature. Subsequently, based on the validated model, an investigation was conducted to determine the relationship between pressure loss and various factors, including flow velocity, combined angle, particle concentration, and particle size. Finally, the changes in velocity distribution, particle concentration, and turbulent kinetic energy were analyzed. The results indicate that the pressure loss increases with the flow velocity, tends to decrease with the combined angle, and increases with the particle concentration. The relationship between pressure loss and particle size is more complex. The velocity distribution, particle concentration, and turbulent kinetic energy exhibit the variations caused by different factors., Competing Interests: The authors declare there is no conflict., (© 2024 The Authors This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).)

Hydrodynamic cavitation (HC) has emerged as a promising technology for water disinfection. Interestingly, when subjected to specific cavitation pressures, jet pump cavitation reactors (JPCRs) exhibit effective water treatment capabilities. This study investigated the cavitation flow and vorticty transport in a JPCR with various area ratios by utilizing computational fluid dynamics. The results reveal that cavitation is more likely to occur within the JPCR as the area ratio becomes smaller. While as the area ratio decreases, the limit flow ratio also decreases, leading to a reduced operational range for the JPCR. During the cavitation inception stage, only a few bubbles with limited travel distances are generated at the throat inlet. A stable cavitation layer developed between the throat and downstream wall during the limited cavitation stage. In this phase, the primary flow carried the bubbles towards the outlet. In addition, it was found that the vortex stretching, compression expansion, and baroclinic torque terms primarily influence the vorticity transport equation in this context. This work may provide a reference value to the design of JPCRs for water treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

This study aims to assess the influence of a rib on the base pressure and the flow development in an abruptly expanded duct at sonic Mach number. Initially, the simulations were done to validate the experimental results, keeping all the parameters the same. Accordingly, a duct-of-area ratio of 6.25 was considered for validation. Five ribs of aspect ratios 3:1, 3:2, and 3:3 were used as a first step, and simulations were performed for the same nozzle pressure ratios. Results indicate that for an area ratio of 6.25, there is a continuous decrease in the base pressure despite the nozzles being highly under-expanded. The lower aspect ratio of the rib tends to reduce the base pressure, whereas a higher aspect ratio effectively increases the base pressure for an area ratio of 6.25. Later simulations considered a single rib instead of five ribs, varying the rib's heights from 1 mm to 5 mm. Results show that the base pressure increases considerably when rib heights are 4 mm and 5 mm. The influence of ribs at two duct diameters (25 mm and 18 mm) is studied to assess the impact of a decrease in the area ratio and, hence, a decrease in the relief available to the flow. Results of duct 18 mm show that passive control becomes very effective when a rib of 3 mm height is located at a 3D position. The differences in the base pressure, velocity, and pressure field for each case are explored. The simulation results indicate that the rib breaks the primary vortex at the base and forms multiple vortices. Turbulent kinetic energy increases in the presence of ribs more than without a rib., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests., (© 2024 The Authors. Published by Elsevier Ltd.)

During the actual construction of tunnel sidewall lining, construction workers often use only one or two windows per layer for pouring in order to reduce the construction sequence, which often leads to a reduction in the quality of tunnel sidewall concrete pouring. Therefore, this study analysed the necessity of the window-by-window pouring of sidewall lining through the study of concrete flow characteristics of the tunnel sidewall lining pouring process, and the reasonable spacing of pouring windows was analysed. This study firstly verified the accuracy of the simulation parameters and the feasibility of the simulation method of the lining pouring process through indoor experiments and simulation analyses, and then it numerically simulated and analysed the flow of concrete during the lining pouring process of tunnel sidewalls. The following conclusions were made: the smaller the slump of the freshly mixed concrete, the higher the pumping flow rate; additionally, the shorter the one-time pouring distance, the smaller the spacing of the trolley feeding window should be. Furthermore, this study makes suggestions for the reasonable spacing of pouring trolleys under several working conditions.

With a large number of railroad and highway tunnels opening for operation, the diseases caused by hidden lining defects are increasing. The study of flow characteristics of freshly mixed concrete during tunnel lining casting is the key to revealing the formation mechanism of hidden defects. This paper revealed the location of blank lining formation by investigating the circumferential and longitudinal flow characteristics of concrete in the vault during tunnel pouring to provide suggestions for improving the quality of tunnel lining pouring for the various projects. This paper adopted the method of indoor testing, selected the suitable working conditions and flow parameters, validated the accuracy of the test with a numerical simulation, and simulated the secondary lining pouring process of the tunnel arch from the circumferential direction and longitudinal direction. This revealed the flow characteristics of the freshly mixed concrete in the process of pouring the arch lining. The flow of concrete in the arch lining was basically characterized by two major features which were similar to the flow in the pumping pipe and the layered flow. It also revealed the relationship between the concrete flow rate, flow distance, and the location of the formation of the blank lining risk zone with the slump of the concrete, the pumping pressure, and the radius of the tunnel.

The pollutants emitted by traveling vehicles are prone to accumulation inside urban highway tunnels, which poses a serious threat to the driving safety and health of passengers. This study employed the dynamic mesh method to simulate a traveling vehicle and investigated the coupling effect of vehicle wake and jet flow on the dispersion characteristics of pollutants in urban highway tunnels. To ensure the accuracy of the numerical simulation results, the turbulence model (realizable k-ε model) and dynamic mesh model were validated through field tests. The results revealed that jet flow can disrupt the large-scale longitudinal vortices pattern in the wake region, whereas vehicle wake can simultaneously weaken the entrainment strength of jet flow. The jet flow was found to be decisive in the space with a height greater than 4 m, whereas the vehicle wake intensity was considerably stronger at the bottom space of the tunnel, leading to the accumulation of pollutants in the passenger breathing zone. To evaluate the effect of jet fans on pollutants in the breathing zone, an innovative dilution efficiency was proposed. The dilution efficiency can be significantly affected by the intensity of vehicle wake and turbulence. Moreover, the dilution efficiency of alternative jet fans was better than that of traditional jet fans., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Following up on a proof of concept, this publication presents a new method for mixing mapping on falling liquid films. On falling liquid films, different surfaces, plain or structured, are common. Regarding mixing of different components, the surface has a significant effect on its capabilities and performance. The presented approach combines marker-free and molecule-sensitive measurements with cross-section mapping to emphasize the mixing capabilities of different surfaces. As an example of the mixing capabilities on falling films, the mixing of sodium sulfate with tap water is presented, followed by a comparison between a plain surface and a pillow plate. The method relies upon point-by-point Raman imaging with a custom-built high-working-distance, low-depth-of-focus probe. To compensate for the long-time measurements, the continuous plant is in its steady state, which means the local mixing state is constant, and the differences are based on the liquids' position on the falling film, not on time. Starting with two separate streams, the mixing progresses by falling down the surface. In conclusion, Raman imaging is capable of monitoring mixing without any film disturbance and provides detailed information on liquid flow in falling films.

Turbulence generated within the vegetated confluence system is important for water quality and river management. In this study, we conducted a series of experiments to explore the extent to which emergent rigid vegetation in the confluence channel influences hydrodynamic characteristics and contaminant transport. First, a series of tests with increasing discharge ratios (from 0.35, 0.5, and 1) was conducted to quantify the effects of the discharge ratio on hydrodynamic conditions within the vegetated confluence. Then, tests with different discharge ratios were also set up to explore how contaminants released locations and modes (line and point source) influence the transport and mixing of contaminants. The results showed that increasing the discharge ratio induced larger momentum in the confluence area. The increase in discharge ratio rendered the circulation stronger, and its position came earlier in the non-vegetative area. In addition, the dimensionless turbulent kinetic energy peaked near the interface of the non/vegetated zone. With the increase in the discharge ratio, the dimensionless turbulent kinetic energy was found to be smaller. In the contaminants transport tests, the results revealed larger discharge ratio could speed up contaminants transport and mixing. The applications from this study would be helpful to pollutant transport management in natural confluences., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Compound cross-sections with vegetated floodplains are a common type of cross-section in debris-flow gullies. Floodplain vegetation participates in large-scale debris flow events and regulates debris-flow discharge. Extensive research has been conducted on the water flow characteristics of compound rivers. However, few studies have investigated the debris flow characteristics of compound channels in mountainous areas, particularly those of debris flow and flash flood inundation areas with vegetation. This study discusses the section characteristics of debris flow gullies with vegetated floodplains, gully evolution processes, and their influence on debris flow. The results show that the compound debris flow gully with a vegetated floodplain is formed in the gully from the mature stage to the old-mature stage. The compound sections are developed in flow areas with a gentle slope, which can be bilateral floodplain, unilateral floodplain, and multi-main gully floodplain types. Owing to the vegetation of the floodplain, the roughness of the channel increases, which makes the beach roughness coefficient much larger than that for the main channel. In the integrated Manning coefficient method, the error in resolving the flow velocity and discharge is large and cannot reflect the difference in velocities of the floodplain and main channel, therefore the sectional splitting method is most applicable. Influencing debris flow movement, limiting channel migration, and retaining debris flow to the main channel were the main contributions of the riparian forest zone., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

To promote the widespread use of fly ash (FA) and coal gasification slag (CGS) in mine filling, reducing the amount of cement and promoting the sustainable development of mining enterprises are essential. In this study, decarbonized CGS (DCGS) was prepared from CGS through decarbonization. A new DCGS-FA filling material was prepared using DCGS, FA, cement (3 wt.%), sodium sulfate (SS), and aeolian sand (AS). The effects of different mass ratios (1/9-5/5) of DCGS/FA on the properties of new filling materials were investigated. The results indicate that CGS can be used with FA to prepare filling materials after decarbonization. The flow performance of the DCGS-FA filling material is positively correlated with the mass ratio of DCGS/FA, while the mechanical properties are negatively correlated. The 28-day unconfined uniaxial compressive strength (UCS) of all specimens met the mechanical requirements (UCS ≥ 1.0 MPa). The types of hydration products were determined through X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The main hydration products of DCGS-FA filling materials are ettringite (AFt) and C-S-H gel. The results of the TG/DTG test of 28 days revealed that an increase in the DCGS/FA mass ratio would reduce the content of hydration products in filling materials. When the mass ratio increased from 1/9 to 5/5, the content of hydration products in the filling material decreased by 54.5%. This study provides a new concept for the resource utilization of CGS and FA in mine filling, which can significantly reduce the amount of cement in filling materials and promote the sustainable development of mine filling., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Substrate clogging is one of the major operation challenges of subsurface flow constructed wetlands (SSF-CWs). And the phosphorus (P) removal performance and stability of P accumulation of SSF-CWs would be varied with the development of substrate clogging. In this study, three horizontal SSF-CWs microcosms with different clogging degrees were conducted to explore the mechanism of P accumulation behavior influenced by substrate clogging. Increase in clogging degree resulted in hydraulic retention time (HRT) diminution and adsorption sites increase, which jointly led to reduced P removal efficiency at low clogging degree (L-CW), however, higher P removal efficiency was obtained as adsorption sites increase offset HRT diminution at high clogging degree (H-CW). Substrate adsorption was the primary removal pathway in all SSF-CW systems. It accounted for 77.86 ± 2.63% of the P input in the H-CW, significantly higher than the control (60.08 ± 4.79%). This was attributed to a higher proportion of Fe/Al-P accumulated on the substrate of H-CW, since clogging aggravated the anaerobic condition and promoted the generation of Fe ions. The increase in clogging degree also elevated the release risk of the accrued P in SSF-CWs, since Fe/Al-P was considered bioavailable and readily released under environmental disturbance. The obtained results provide new insights into the P transport and transformation in SSF-CWs and would be helpful to optimize substrate clogging management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background and Purpose: Nanofluids are a new class of heat transfer fluids that are used for different heat transfer applications. The transport characteristics of these fluids not only depend upon flow conditions but also strongly depend on operating temperature. In respect of these facts, the properties of these fluids are modified to measure the temperature effects and used in the governing equations to see the heat and mass flow behavior. Design of Model: Consider the nanofluids which are synthesized by dispersing metallic oxides (SiO 2 , Al 2 O 3 ), carbon nanostructures (PEG-TGr, PEG-GnP), and nanoparticles in deionized water (DIW), with (0.025-0.1%) particle concentration over (30-50 °C) temperature range. The thermophysical properties of these fluids are modeled theoretically with the help of experimental data as a function of a temperature and volume fraction. These models are further used in transport equations for fluid flow over both wedge and plate. To get the solution, the equations are simplified in the shape of ordinary differential equations by applying the boundary layer and similarity transformations and then solved by the RK method., Results: The solution of the governing equation is found in the form of velocity and temperature expressions for both geometries and displayed graphically for discussion. Moreover, momentum and thermal boundary layer thicknesses, displacement, momentum thicknesses, the coefficient of skin friction, and Nusselt number are calculated numerically in tabular form., Finding: The maximum reduction and enhancement in velocity and temperature profile is found in the case of flow over the plate as compared to the wedge. The boundary layer parameters are increased in the case of flow over the plate than the wedge.

Objectives: Subclinical leaflet thrombosis is a silent phenomenon commonly observed following transcatheter aortic valve implantation (TAVI). Leaflet thrombosis is associated with ischaemic complications and structural valve deterioration. Prior studies have shown that blood stasis in neo-sinus contributes to the initiation and growth of subclinical leaflet thrombosis. This study aimed to quantify temporal and spatial characteristics of the flow field from a fundamental perspective., Methods: in vitro experimental analysis and fluid-solid interaction simulations were employed to characterize the flow field of a transcatheter aortic valve (TAV) with an intra-annular design in a pulse duplicator. Blood residence time (BRT) and flow-induced viscous shear stress were measured in the neo-sinus and on the surface of TAV leaflets., Results: Temporal and spatial velocity variations were observed in neo-sinus, indicating that the flow is time-dependent and fully three-dimensional. The degree of blood stasis in the neo-sinus (bulk fluid) and on the surface of the TAV leaflets highly depends on the local flow characteristics. Regional flow variation in the neo-sinus resulted in substantial variations in BRT magnitude in the neo-sinus and on the surface of the TAV leaflet. Areas with a high degree of blood stasis were observed near the fixed boundary edge of the leaflets., Conclusions: The study indicated that leaflet motion is a primary driver of flow in neo-sinus. Considering the substantial variations in BRT magnitude in the neo-sinus (bulk fluid), blood stasis should be quantified locally on the surface of foreign (valve) materials to avoid errors in forecasting the risk of subclinical leaflet thrombosis in patients undergoing TAVI., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.)

This paper proposed an improved flow-focusing microchannel with a constricted continuous phase inlet to increase microbubble generation frequency and reduce microbubbles' diameter. The design variables were obtained by Latin hypercube sampling, and the radial basis function (RBF) surrogate model was used to establish the relationship between the objective function (microbubble diameter and generation frequency) and the design variables. Moreover, the optimized design of the nondominated sorting genetic algorithm II (NSGA-II) algorithm was carried out. Finally, the optimization results were verified by numerical simulations and compared with those of traditional microchannels. The results showed that dripping and squeezing regimes existed in the two microchannels. The constricted continuous phase inlet enhanced the flow-focusing effect of the improved microchannel. The diameter of microbubbles obtained from the improved microchannel was reduced from 2.8141 to 1.6949 μm, and the generation frequency was increased from 64.077 to 175.438 kHz at the same capillary numbers (Ca) compared with the traditional microchannel. According to the fitted linear function, it is known that the slope of decreasing microbubble diameter with increasing Ca number and the slope of increasing generation frequency with increasing Ca number are greater in the improved microchannel compared with those in the traditional microchannel.

The paper describes the introduction and estimation of performance criteria for the gelling agent injection technology based on a general approach to modeling physical and chemical enhanced oil recovery (EOR) methods. The current mathematical models do not include performance criteria for the process of gelling agent injection and do not allow for assessing the level of success of a treatment job in production wells. The paper introduces such criteria for the first time. To simulate the effect on injection wells, the mass conservation laws and the generalized flow law are used, and closing relations for the gelling rate are taken into account. A conformance control coefficient is introduced which characterizes the positive effect of well treatments and injectivity drop which characterizes the negative effect. The performance criteria allow for identifying the wells where the treatment jobs were the most successful. The model verification, based on the comparison of post-treatment injectivity estimated in the developed model, with Rosneft's field data showed a satisfactory match. The developed correlations can be used as the basis for a surrogate model that allows for avoiding building sector geological and flow simulation models of the treated zone.

The present study aims at understanding the effects of fuel preheating on engine characteristics of waste animal fat-oil (WAF-O) biodiesel in a single-cylinder CI engine, with the preheating technique proposed as an effective means for enhancing the fuel properties. To understand the effects of the preheated fuel, the WAF-O biodiesel was preheated at 60, 80, 100 and 120 °C and tested along with neat diesel and unheated WAF-O biodiesel. For this purpose, biodiesel was produced from different animal wastes by means of KOH-assisted ethanol-based transesterification, reporting its maximum yield as 96.37 ± 1.8%, with significant distribution of unsaturated oleic acid, saturated palmitic acid and stearic acid. Upon evaluating its fuel characteristics as per ASTM D6751 standards, a rise in preheating temperature by 1 °C reduced the density and kinematic viscosity of WAF-O biodiesel by 0.383 kg/m3 and 0.025 mm2/s, respectively, and was explained by the weakening of intermolecular forces between its fatty acid ester molecules. Preheated samples reported superior combustion characteristics by exhibiting increased in-cylinder pressure (2.24%, on average) and heat release rates in addition to their shortened ignition delay (1−4 °CA). Furthermore, preheating of WAF-O biodiesel reduced its specific fuel consumption and increased its brake thermal efficiency by 7.86% (on average) and 9.23% (on average), respectively. However, higher preheating temperatures (>120 °C) resulted in increased fuel consumption owing to its varied flow characteristics. In addition to the changes in combustion characteristics, preheating WAF-O bio-diesel also resulted in reduced carbon monoxide, nitrous oxide and hydrocarbon emission by 13.88%, 7.21% and 26.94%, respectively, and increased carbon dioxide emission by 7.58%. Summing up, the enhancements in overall engine characteristics of preheated samples were accounted for by their improvised fuel injection characteristics due to their reduced density and viscosity, which ensured for their effective combustion.

When the size of a liquid crystal display (LCD) increases, the light guiding plate (LGP) as the main part of the LCD must adopt a wedge-shaped plate to reduce its weight (the thickness of the LGP decreases because of this) and guide the light to the LCD screen. Micro-injection molding (MIM) is commonly used to manufacture LGPs. During the filling phase of MIM, the entire entering polymer melt front of the LGP should reach the end of the mold cavity at the same time. In this way, there will be no shrinkage or warpage of the LGP in its subsequent application, but it is difficult for the wedge-shaped LGP to meet these requirements. Therefore, the authors hoped to investigate MIM process parameters to change this situation. Otherwise, the LGP is easily deformed during the manufacturing process. Flow characteristics of LGPs were investigated during the filling phase of MIM in this study. Experimental and 3D numerical simulations were used to analyze the hysteresis, i.e., the advance of the polymer melt front of the LGP in MIM. Study results showed that a low injection speed caused a hysteresis effect of the plastic melt front, the solution was to increase the injection speed to improve the situation and an injection speed of 10 cm/s could achieve uniformity of the melt front in MIM. The research results showed that the filling situation of the LGP of MIM in the experiment was very close to that of the 3D numerical simulation.

Vascular graft maturation is associated with blood flow characteristics, such as velocity, pressure, vorticity, and wall shear stress (WSS). Many studies examined these factors separately. We aimed to examine the remodeling of arterio-venous fistulas (AVFs) and loop-shaped venous interposition grafts, together with 3D flow simulation. Thirty male Wistar rats were randomly and equally divided into sham-operated, AVF, and loop-shaped venous graft (Loop) groups, using the femoral and superficial inferior epigastric vessels for anastomoses. Five weeks after surgery, the vessels were removed for histological evaluation, or plastic castings were made and scanned for 3D flow simulation. Remodeling of AVF and looped grafts was complete in 5 weeks. Histology showed heterogeneous morphology depending on the distribution of intraluminal pressure and WSS. In the Loop group, an asymmetrical WSS distribution coincided with the intima hyperplasia spots. The tunica media was enlarged only when both pressure and WSS were high. The 3D flow simulation correlated with the histological findings, identifying "hotspots" for intimal hyperplasia formation, suggesting a predictive value. These observations can be useful for microvascular research and for quality control in microsurgical training.

Technical liquid flow films are the basic arrangement for gas fluid transitions of all kinds and are the basis of many chemical processes, such as columns, evaporators, dryers, and different other kinds of fluid/fluid separation units. This publication presents a new method for molecule sensitive, non-contact, and marker-free localized concentration mapping in vertical falling films. Using Raman spectroscopy, no label or marker is needed for the detection of the local composition in liquid mixtures. In the presented cases, the film mapping of sodium sulfate in water on a plain surface as well as an added artificial streaming disruptor with the shape of a small pyramid is scanned in three dimensions. The results show, as a prove of concept, a clear detectable spectroscopic difference between air, back plate, and sodium sulfate for every local point in all three dimensions. In conclusion, contactless Raman scanning on falling films for liquid mapping is realizable without any mechanical film interaction caused by the measuring probe. Surface gloss or optical reflections from a metallic back plate are suppressed by using only inelastic light scattering and the mathematical removal of background noise.

This study presents the experimental results of the flow characteristics, such as the flow adjustment, velocity profiles, mixing layer, and the momentum exchange, in the partially vegetated channel with homogeneous and heterogeneous layouts. Three cases are considered, including two homogeneous canopies with uniform sparse and dense vegetation patches respectively, and a heterogeneous canopy consisting of alternating patches of both densities. Results show that heterogeneous canopy requires a longer adjustment distance to reach the quasi-equilibrium region, compared with the homogenous canopy of the same density. In heterogeneous canopy flow, the mixing layer width and the momentum thickness fluctuates with the alternation of vegetation density. The increased values for these two parameters compared to those values for the homogeneous canopies indicate that the greater resistance and momentum loss occur for the heterogeneous layout. A wavy region of the enhanced in-plane turbulence kinetic energy (TKE) is observed in the heterogeneous canopy, suggesting a comparatively more chaotic flow condition, whereas the contours of in-plane TKE are smooth in homogeneous canopies. The presence of the coherent structures in heterogeneous canopy is identified by spectral analysis and the quasi-periodic fluctuations of velocities. The Reynolds stress associated with the coherent structures is found to be the dominator of the contribution to the total Reynolds stress. The comparison between the homogenous canopies of different density is also conducted. These results will be of practical importance for the design of vegetation layouts in water ecological restoration projects and for river management., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The placement of boulder or boulder cluster in rivers can increase or repair the complexity of river structure and the diversity of hydraulic conditions, which is very important for the habitat of many aquatic organisms. In this study, the diamond-type boulder cluster was modeled as four hemispheres exposed to a fully developed turbulent open channel flow. Numerical simulation was conducted to investigate the time-averaged flow characteristics, three-dimensional coherent structures, turbulence characteristics, and flow diversity index at different spacing ratios L/D (the ratio of the distance L to the diameter D, 1.0 ≤ L/D ≤ 3.5, where L is the center-to-center distance between two adjacent hemispheres and D is the diameter of the hemisphere). The results show that with the increase of the spacing ratio, the shear layer on the side of the gap flow gradually strengthens, and the single Karman vortex street in the wake region of the hemisphere array is suppressed. The time-averaged peak velocity in the gap flow gradually decreases with the increase of the spacing ratio, and the single of the recirculation zone behind the hemisphere array transforms into the recirculation zone behind each hemisphere, and the length of the each recirculation zone increases to the same. The turbulence intensity of the array first increases with the increase of the spacing ratio and then gradually decreases to a constant, reaching the peak intensity at L/D = 2. Based on the Shannon entropy concept, the flow diversity index in the zone of influence (ZOI) is calculated by considering the velocity and turbulence kinetic energy. The flow diversity index is the largest in the ZOI at the spacing ratio of 1.5., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A microfluidic passive valve (MPV) is important for precise flow control, and it determines the reliability of the microfluidic system. In this paper, a novel MPV capable of delivering a constant flow rate independently of inlet pressure changes is proposed. The flow rate of the MPV is adjusted by the difference between the fluid force on the upper surface of the valve core and the spring force. The constant flow rate of the MPV is maintained by automatically changing the size of the gap channel formed by the groove on the valve core and the baffle on the valve body. The nearly constant flow rate of the MPV is 6.26 mL/min, with a variation of 6.5% under the inlet pressure varied from 1.25 kPa to 3.5 kPa. In addition, the flow characteristics of the MPV are analyzed by numerical simulation. With the increase in the inlet pressure, the maximum velocity gradually increases, while the increment of the maximum velocity decreases. In the movement process of the valve core, the region of pressure drop becomes larger. This work has a certain reference value for the design and research of the MPVs with high throughput liquid delivery.

Ventricular assist devices or total artificial hearts can be used to save patients with heart failure when there are no donors available for heart transplantation. Blood pumps are integral parts of such devices, but traditional axial flow blood pumps have several shortcomings. In particular, they cause hemolysis and thrombosis due to the mechanical contact and wear of the bearings, and they cause blood stagnation due to the separation of the front and rear guide wheel hubs and the impeller hub. By contrast, the implantable axial flow, maglev blood pump has the characteristics of no mechanical contact, no lubrication, low temperature rise, low hemolysis, and less thrombosis. Extensive studies of axial flow, maglev blood pumps have shown that these pumps can function in laminar flow, transitional flow, and turbulent flow, and the working state and performance of such pumps are determined by their support mechanisms and flow channel. Computational fluid dynamics (CFD) is an effective tool for understanding the physical and mechanical characteristics of the blood pump by accurately and effectively revealing the internal flow field, pressure-flow curve, and shear force distribution of the blood pump. In this study, magnetic levitation supports were used to reduce damages to the blood and increase the service life of the blood pump, and a conical impeller hub was used to reduce the speed, volume, and power consumption of the blood pump, thereby facilitating implantation. CFD numerical simulation was then carried out to optimize the structural parameters of the conical axial maglev blood pump, predict the hemolysis performance of the blood pump, and match the flow channel and impeller structure. An extracorporeal circulation simulation platform was designed to test whether the hydraulic characteristics of the blood pump met the physiological requirements. The results showed that the total pressure distribution in the blood pump was reasonable after optimization, with a uniform pressure gradient, and the hemolysis performance was improved.

This study evaluated the effects of pretreatments (blanching (60 and 95 °C) and boiling) and drying methods (freeze-drying and oven drying) on the quality characteristics of potato flour derived from three potato varieties, namely, Shangi, Unica, and Dutch Robjin. The percentage flour yield, color, particle size distribution, flow characteristics, microstructural and functional properties of the potato flour were determined. Unica recorded the least peeling loss, while the Dutch Robjin variety had the highest. Color parameters were significantly affected ( p < 0.05) by the pretreatments and drying methods. Freeze drying produced lighter potato flour (L* = 92.86) compared to the other methods. Boiling and blanching at 95 °C followed by oven drying recorded a low angle of repose and compressibility index, indicating better flow characteristics. The smallest particle size (56.5 µm) was recorded for the freeze-drying treatment, while boiling followed by oven drying had the largest particle size (307.5 µm). Microstructural results indicate that boiling and blanching at 95 °C, followed by oven drying resulted in damaged starch granules, while freeze-drying and low-temperature blanching (60 °C) maintained the native starch granule. Particle size and the solubility index of potato flour showed strong positive correlation. This study revealed that the pretreatments and drying methods affected potato flour's physical and microstructural parameters differently, resulting in changes in their functionality.

This paper focuses on the flow and thermal characteristics of the lubricant film in the micro clearance of a hydrodynamic journal bearing (HJB) at high rotating speed. A thermohydrodynamic (THD) method consists of the Reynolds equation coupled with energy and viscosity-temperature equation with considering the cavitation is put forward. The 3D surface diagrams of the lubricant film thickness, pressure, temperature, liquid mass fraction, flow rate and heat dissipation distributions under different geometric, operating, slip and no-slip boundary conditions are systemically exhibited and analyzed. The results show that with the rise of eccentricity or length diameter ratio, the maximum peaks of pressure, temperature and heat dissipation are rapidly increased, the cavitation is aggravated, and the flow rate is accelerated in different extent. As the bearing speed accelerating, the maximum peak of temperature is strongly increased, whereas, the distinction between peaks of flow rate and heat dissipation is magnified and reduced, respectively. It provides a fruitful inside view of the inner flow and thermal characterizations of HJB for further understanding its flow-thermal interaction mechanisms and offers theoretical support for improving its working performance.

Plant-based meat analogues that mimic the characteristic structure and texture of meat are becoming increasingly popular. They can be produced by means of high moisture extrusion (HME), in which protein-rich raw materials are subjected to thermomechanical stresses in the extruder at high water content (>40%) and then forced through a cooling die. The cooling die, or generally the die section, is known to have a large influence on the products' anisotropic structures, which are determined by the morphology of the underlying multi-phase system. However, the morphology development in the process and its relationship with the flow characteristics are not yet well understood and, therefore, investigated in this work. The results show that the underlying multi-phase system is already present in the screw section of the extruder. The morphology development mainly takes place in the tapered transition zone and the non-cooled zone, while the cooled zone only has a minor influence. The cross-sectional contraction and the cooling generate elongational flows and tensile stresses in the die section, whereas the highest tensile stresses are generated in the transition zone and are assumed to be the main factor for structure formation. Cooling also has an influence on the velocity gradients and, therefore, the shear stresses; the highest shear stresses are generated towards the die exit. The results further show that morphology development in the die section is mainly governed by deformation and orientation, while the breakup of phases appears to play a minor role. The size of the dispersed phase, i.e., size of individual particles, is presumably determined in the screw section and then stays the same over the die length. Overall, this study reveals that morphology development and flow characteristics need to be understood and controlled for a successful product design in HME, which, in turn, could be achieved by a targeted design of the extruders die section.

The development of oil and gas resources is gradually transferring to the deep sea, and the hydrate plugging of submarine pipelines at high pressures and low temperatures is becoming an important problem to ensure the safety of pipeline operations. The swirl flow is a new method to expand the boundary of hydrate safe flow. Numerical simulation of the hydrate slurry flow characteristics in a horizontal pipeline by twisted band has been carried out, and the flow of CO 2 hydrate slurry in low concentration has been simulated by the RSM and DPM models. The results show that the heat transfer efficiency is also related to Re and particle concentration. The velocity distribution has the form of symmetrical double peaks, and the peaks finally merge at the center of the pipeline. Vortexes firstly appear on both sides of the edge of the twisted band, and then move to the middle part of the twisted band. Finally, the vortex center almost coincides with the velocity center. The rotation direction of hydrate particles is the same as the twisted direction of the twisted band, twist rate (Y) is smaller, Re is larger, and the symmetric vortex lines merge farther away. The initial swirl number is mainly related to Y, but not Re. The swirl flow attenuates exponentially, and its attenuation rate is mainly related to Re, but not Y. Compared with ordinary pipelines, the swirl flow can obviously improve the transportation distance of hydrate slurry.

Open-cell metal foams are porous medium for thermo-fluidic systems. However, their complex geometry makes it difficult to perform time-resolved (TR) measurements inside them. In this study, a TR particle image velocimetry (PIV) method is introduced for use inside open-cell metal foam structures. Stereolithography 3D printing methods and conventional post-processing methods cannot be applied to metal foam structures; therefore, PolyJet 3D printing and post-processing methods were employed to fabricate a transparent metal foam replica. The key to obtaining acceptable transparency in this method is the complete removal of the support material from the printing surfaces. The flow characteristics inside a 10-pore-per-inch (PPI) metal foam were analyzed in which porosity is 0.92 while laminar flow condition is applied to inlet. The flow inside the foam replica is randomly divided and combined by the interconnected pore network. Robust crosswise motion occurs inside foam with approximately 23% bulk speed. Strong influence on transverse motion by metal foam is evident. In addition, span-wise vorticity evolution is similar to the integral time length scale of the stream-wise center plane. The span-wise vorticity fluctuation through the foam arrangement is presented. It is believed that this turbulent characteristic is caused by the interaction of jets that have different flow directions inside the metal foam structure. The finite-time Lyapunov exponent method is employed to visualize the vortex ridges. Fluctuating attracting and repelling material lines are expected to enhance the heat and mass transfer. The results presented in this study could be useful for understanding the flow characteristics inside metal foams.

Hydrodynamic conditions often affect the eutrophication process and play a key role in algal growth in reservoirs. A promising approach for controlling algal blooms in reservoirs is to create adverse hydrodynamic conditions by implementing reservoir operation strategies. However, research on this method is still nascent and does not support practical applications due to the lack of quantitative hydrodynamic thresholds. In this paper, field observations of algal growth from April 2015 to August 2016 were conducted, and a three-dimensional (3D) model that couples hydrodynamics and water temperatures for the Zipingpu Reservoir was established. Low flow velocities (V) and low Reynolds numbers (Re) in the Longchi tributary are favorable for dinoflagellate growth and accumulation, which can explain why dinoflagellate blooms are more likely to occur in the tributary. A temperature of 18-22 °C is considered a precondition for Peridiniopsis penardii blooms, suggesting that freshwater dinoflagellate species may prefer lower temperatures than marine dinoflagellate species. Shallow mixing layer depth (Z mix ) is conducive to Peridiniopsis penardii gathering in the upper water layers and promotes growth. The shallow euphotic layer depth (Z eu ) was speculated to promote the dominance of this species by stimulating its heterotrophy and inhibiting other algal autotrophy. Furthermore, a boundary line analysis was introduced to characterize the relationships between algal biomass and hydrodynamic indicators. Thus, the thresholds for V, Re, and Z mix /Z eu were determined to be 0.034 m s -1 , 6.7 × 10 4 , and 1.7, respectively. Either accelerating horizontal flow to exceed the thresholds of V and Re or facilitating vertical mixing to exceed the threshold of Z mix /Z eu can prevent dinoflagellate blooms. Therefore, the summarized hydrodynamic threshold system is suggested to be an effective standard for controlling dinoflagellate blooms in the reservoir. Moreover, this study can provide a useful reference for understanding the mechanism of freshwater dinoflagellate blooms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

It is well-established that hydrodynamics affect the settlement of biofouling organisms. Laboratory studies have demonstrated a connection between larval attachment rates and the prevalence of time windows that satisfy certain instantaneous flow conditions. However, it is unclear whether a link exists between short-term hydrodynamics and long-term macrofouling survival and growth, or if it is applicable at an ecosystem-wide level. This study used single bubble stream aeration in field and laboratory experiments to find critical flow characteristics that correlate to long-term, multi-species fouling prevention. The research was accomplished by combining PIV-derived flow statistics with fouling severity measured over seven weeks in the field. Flows with a decreasing proportion of time windows defined by a flow speed < 15.1 mm s -1 for longer than 0.03 s correlated to decreased biofouling growth and survival. These results provide a potential framework for studying and comparing flow fields that successfully inhibit biofouling growth.

Ethambutol hydrochloride (ETB), high dose anti-tubercular drug exhibits poor micromeritics and compressibility. The current study aimed to enhance flow, compressibility and packing characteristics, thereby improving processability of ETB by spherical agglomeration. Quasi emulsion solvent diffusion method was used for agglomeration process in which saturated aqueous ETB solution was prepared and the crystallization was carried out subsequently at different ratios of acetone and ethyl acetate which act as anti-solvent. Further the process was optimised statistically using 3 2 factorial design keeping 'speed of stirring' and 'ratio acetone and ethyl acetate' as independent variables and particle size as dependent variable. Optimised batch of ethambutol hydrochloride spherical agglomerates (ETB-SA) was characterised for sieve analysis, solid state characteristics and Kawakita analysis. The uniformity of ETB-SA was observed with SEM while XRPD studies revealed reduction in crystallinity for ETB-SA. DSC and FTIR indicated no polymeric or chemical alteration during crystallization process. The flow properties of ETB-SA were found superior and its Kawakita parameters indicated improved packability and flowability compared to ETB. ETB has high solubility in water therefore was no significant difference was observed in in vitro dissolution of ETB and ETB-SA. Thus spherical agglomeration, a revered particle engineering technique, continues to be a salient approach for enhancing processability of high-dose drugs like ETB.

PM 2.5 separator directly affects the accuracy of PM 2.5 sampling. The specification testing and evaluation for PM 2.5 separator is particularly important, especially under China's wide variation of terrain and climate. In this study, first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM 2.5 separators. A uniform mixing chamber was developed to make particles mix completely. The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%, and the particle size distribution obeyed logarithmic normal distribution with an R 2 of 0.996. The flow rate deviation between the measurement and the set point flow rate agreed to within ±1.0% in the range of -40 to 50°C. Secondly, the separation, flow and loading characteristics of three cyclone separators (VSCC-A, SCC-A and SCC112) were evaluated using this system. The results showed that the 50% cutoff sizes (D 50 ) of the three cyclones were 2.48, 2.47 and 2.44 μm when worked at the manufacturer's recommended flow rates, respectively. The geometric standard deviation (GSD) of the capture efficiency of VSCC-A was 1.23, showed a slightly sharper than SCC-A (GSD =1.27), while the SCC112 did not meet the relevant indicator (GSD = 1.2 ± 0.1) with a GSD = 1.44. The flow rate and loading test had a great effect on D 50 , while the GSD remained almost the same as before. In addition, the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test., (Copyright © 2019. Published by Elsevier B.V.)

Selective catalytic reduction is the main technology to reduce oxides of nitrogen of diesel exhaust. As an important part of the selective catalytic reduction system, the air-assisted urea dosing system regulates the flow rate by adjusting the pump speed, and the flow rate and its metering accuracy directly affect the efficiency of oxides of nitrogen conversion. A mathematical model coupled with the air-assisted urea dosing system and the suction pipeline was built, and the influences of the discharge pressure, pump speed, suction pipeline length, and diameter on the flow characteristics and metering accuracy of the air-assisted urea dosing system were analyzed. The flow rate and metering accuracy of a prototype of the air-assisted urea dosing system were tested under different conditions on a test rig. Results show that the flow stability and metering accuracy of the prototype elevate with increasing the discharge pressure when the prototype has no overfeeding, and it gets down under any discharge pressure when the prototype occurs overfeeding. The flow stability and metering accuracy of the prototype improve with increasing the pump speed, and increase significantly when the suction pipeline length becomes shorter and the diameter gets larger. The metering accuracy of the prototype can achieve to ±2% by optimizing the suction pipeline parameters. The experimental results prove that the proposed mathematical model is effective.

We conducted systematic numerical investigations of the flow characteristics within the entrance region of rectangular microchannels. The effects of the geometrical aspect ratio and roughness on entrance lengths were analyzed. The incompressible laminar Navier-Stokes equations were solved using finite volume method (FVM). In the simulation, hydraulic diameters (Dh) ranging from 50 to 200 µm were studied, and aspect ratios of 1, 1.25, 1.5, 1.75, and 2 were considered as well. The working fluid was set as water, and the Reynolds number ranged from 0.5 to 100. The results showed a good agreement with the conducted experiment. Correlations are proposed to predict the entrance lengths of microchannels with respect to different aspect ratios. Compared with other correlations, these new correlations are more reliable because a more practical inlet condition was considered in our investigations. Instead of considering the influence of the width and height of the microchannels, in our investigation we proved that the critical role is played by the aspect ratio, representing the combination of the aforementioned parameters. Furthermore, the existence of rough elements obviously shortens the entrance region, and this effect became more pronounced with increasing relative roughness and Reynolds number. A similar effect could be seen by shortening the roughness spacing. An asymmetric distribution of rough elements decreased the entrance length compared with a symmetric distribution, which can be extrapolated to other irregularly distributed forms., Competing Interests: The authors declare no conflict of interest.

Jet pump is a type of cavitation reactor with great potential because of strong shear flow. In the present paper, experiments were carried out to investigate the cavitation characteristics of jet pump cavitation reactors (JPCRs) with different throat lengths, throat types and diffuser angles. Cavitation images and sound pressure signals in water corresponding to the hydraulic parameters are introduced to judge the aggressive intensity of cavitation in JPCRs. The flow ratios varying from the maximum limited value to -1 were measured for all JPCRs. It suggests that throat structure plays a more important role in the cavitation and flow characteristics of JPCR when compared with diffuser structure. Specifically, convergent throat results in large bubble density in the diffuser while divergent throat results in choke in the throat compared to the original JPCR. And cavitation bubble density in throat increases with increasing throat length. With the decrease of the flow ratio (q > 0), sound pressure level (SPL) decreases from the maximum to the minimum and then increases again. As the flow ratio decreases further (q < 0), SPL keeps on increasing first and then decreases, finally it takes a turn and increases to a stable level. Further study on actual SPL induced by cavitation in JPCR indicates that small diffuser angle, divergent and long throat enhance the aggressive intensity of cavitation. This result is of great significance to the design of JPCR., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The present study aimed to detail the relationship between the flow and structure characteristics of the upper airways and airway collapsibility in obstructive sleep apnea. Using a computational approach, we performed simulations of the flow and structure of the upper airways in two patients having different facial morphologies: retruding and protruding jaws, respectively. First, transient flow simulation was performed using a prescribed volume flow rate to observe flow characteristics within upper airways with an unsteady effect. In the retruding jaw, the maximum magnitude of velocity and pressure drop with velocity shear and vortical motion was observed at the oropharyngeal level. In contrast, in the protruding jaw, the overall magnitude of velocity and pressure was relatively small. To identify the cause of the pressure drop in the retruding jaw, pressure gradient components induced by flow were examined. Of note, vortical motion was highly associated with pressure drop. Structure simulation was performed to observe the deformation and collapsibility of soft tissue around the upper airways using the surface pressure obtained from the flow simulation. At peak flow rate, the soft tissue of the retruding jaw was highly expanded, and a collapse was observed at the oropharyngeal and epiglottis levels. NEW & NOTEWORTHY Aerodynamic characteristics have been reported to correlate with airway occlusion. However, a detailed mechanism of the phenomenon within the upper airways and its impact on airway collapsibility remain poorly understood. This study provides in silico results for aerodynamic characteristics, such as vortical structure, pressure drop, and exact location of the obstruction using a computational approach. Large deformation of soft tissue was observed in the retruding jaw, suggesting that it is responsible for obstructive sleep apnea.

To optimize the designing of microalgae slurry pumping system and enhance the efficiency of microalgae products production, the flow characteristics of microalgae slurries (Chlorella pyrenoidosa) in tube flow were for the first time investigated combining experiments and numerical simulation. The drag reduction behavior of microalgae slurry in the fully developed laminar flow regime was studied. In addition, the transition Reynolds number of microalgae slurries from laminar flow to turbulent flow was about 1000-1300, which was similar to the expression of two-phase flow. To provide a further understanding of flow feature of microalgae slurries in tube, a two-phase mixture model was proposed by considering the heterogeneity of concentration due to the shear-induced microalgae cells migration behavior. Simulation results revealed that the heterogeneous distribution of concentration was affected by average velocity and volume fraction of microalgae slurries, significantly affecting the flow resistance and flow stability of microalgae slurry in the tube flow., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The purpose of this study was to develop a standard reference material that can simulate the flow characteristics of cement paste. For this purpose, it is important to determine the constituent materials of the standard material for cement paste. Generally, cement paste is a mixture of cement and water. To determine the constituent material of cement paste, it was divided into powder that can replace cement and matrix fluid. With the concept of rheology, which can evaluate the flow properties of selected materials quantitatively under certain mixing conditions, experiments were carried out step-by-step according to material composition combination, stage of aging, and material types. As a result, limestone powder was determined to be a cement substitute, and glycerol and water were determined to be a matrix fluid substitute. After an analysis of the compatibility with the required properties of the particulate standard materials, the finally selected standard reference material was found to satisfy the required performance.

Introduction: Vascular-targeted drug delivery is a promising approach for the treatment of atherosclerosis, due to the vast involvement of endothelium in the initiation and growth of plaque, a characteristic of atherosclerosis. One of the major challenges in carrier design for targeting cardiovascular diseases (CVD) is that carriers must be able to navigate the circulation system and efficiently marginate to the endothelium in order to interact with the target receptors., Areas Covered: This review draws on studies that have focused on the role of particle size, shape, and density (along with flow hemodynamics and hemorheology) on the localization of the particles to activated endothelial cell surfaces and vascular walls under different flow conditions, especially those relevant to atherosclerosis., Expert Opinion: Generally, the size, shape, and density of a particle affect its adhesion to vascular walls synergistically, and these three factors should be considered simultaneously when designing an optimal carrier for targeting CVD. Available preliminary data should encourage more studies to be conducted to investigate the use of nano-constructs, characterized by a sub-micrometer size, a non-spherical shape, and a high material density to maximize vascular wall margination and minimize capillary entrapment, as carriers for targeting CVD.

Clinical studies reported that some vulnerable stenoses deformed their shape in a blood vessel based on flow condition. However, the effects of shape variation on flow characteristics remain unclear. The flow characteristics are known to affect vulnerable stenosis rupture and fractional flow reserve (FFR) value which has been widely used as a diagnostic tool for stenosis. Vulnerable stenosis rupture occurs when the structural stress exerted on a fibrous cap exceeds its tolerable threshold. The stress magnitude is determined from the spatial distribution of static pressure around the stenosis. In the present study, the static pressure distribution and the FFR value in deformable stenosis were investigated with related other flow characteristics. Two phantom models were fabricated to mimic deformable and nondeformable stenoses using polydimethylsiloxane. The flow characteristics were observed under a steady-flow condition at three Reynolds numbers (Re=500, 1000, 1500) using a particle image velocimetry. The pressure drop across the stenosis models were measured using a pressure sensor to determine effects of shape deformation on FFR value. Shape variations and jet deflections were clearly observed in the deformable stenosis model, and the effective severity of the stenosis increased up to 17.2%. The shape variations of deformable stenosis model increased the static pressure difference at the upstream and downstream sides of the stenosis. The pressure drop across the deformable stenosis model was significantly higher than that of the nondeformable stenosis model. The present results substantiate that stenosis deformability should be carefully considered to diagnose the rupture of vulnerable stenosis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This paper introduced problems about Automated Peritoneal Dialysis machine(APD) that the lack of technical issues such as the structural design of the complex cavities. To study the flow characteristics of this special structure, the application of ANSYS CFX software is used with k-ε turbulence model as the theoretical basis of fluid mechanics. The numerical simulation of flow field simulation result in the internal model can be gotten after the complex structure model is imported into ANSYS CFX module. Then, it will present the distribution of complex cavities inside the flow field and the flow characteristics parameter, which will provide an important reference design for APD design.

The Vacuum-UV/UV process, an incipient catalyst/chemical-free advanced oxidation process (AOP), is potentially a cost-effective solution for the removal of harmful micropollutants from water. Utilizing a novel mechanistic numerical model, this work aimed to establish a thorough understanding of the degradation mechanisms in the VUV/UV process operating under continuous flow conditions, when compared with the widely applied H2O2/UV AOP. Of particular interest was the examination of the impact of flow characteristics (hydrodynamics) on the degradation efficacy of a target micropollutant during the VUV/UV and H2O2/UV AOPs. While hydroxyl radical (OH) oxidation was the dominant degradation pathway in both processes, the degradation efficacy of the VUV/UV process showed much stronger correlation with the extent of mixing in the photoreactor. Under a uniform flow regime, the degradation efficiency of the target pollutant achieved by the H2O2/UV process with 2- and 5 ppm H2O2 was greater than that provided by the VUV/UV process. Nonetheless, introduction of mixing and circulation zones to the VUV/UV reactor resulted in superior performance compared with the H2O2/UV AOP. Based on the electrical energy-per-order (EEO) analysis, incorporation of circulation zones resulted in a reduction of up to 50% in the overall energy cost of the VUV/UV AOP, while the corresponding reduction for the 5-ppm H2O2/UV system was less than 5%. Furthermore, the extent of OH scavenging of natural organic matter (NOM) on energy efficiency of the VUV/UV and H2O2/UV AOPs under continuous flow conditions was assessed using the EEO analysis., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In this study, we focus on making a double-sided metal plate with an internal structure, such as honeycomb. The stainless steel powder was used in the metal injection molding (MIM) process. The preliminary studies were carried out for the measurement of the viscosity of the stainless steel feedstock and for the prediction of the filling behavior through Computer Aided Engineering (CAE) simulation. PE (high density polyethylene (HDPE) and low density polyethylene (LDPE)) and polypropylene (PP) resins were used to make the sacrificed insert with a honeycomb structure using a plastic injection molding process. Additionally, these sacrificed insert parts were inserted in the metal injection mold, and the metal injection molding process was carried out to build a green part with rectangular shape. Subsequently, debinding and sintering processes were adopted to remove the sacrificed polymer insert. The insert had a suitable rigidity that was able to endure the filling pressure. The core shift analysis was conducted to predict the deformation of the insert part. The 17-4PH feedstock with a low melting temperature was applied. The glass transition temperature of the sacrificed polymer insert would be of a high grade, and this insert should be maintained during the MIM process. Through these processes, a square metal plate with a honeycomb structure was made.

The study advances the idea of using computational fluid dynamics in the process of planning surgical treatment modalities for patients with obstructive airway disorders. It is hypothesized that the a priori knowledge of the functional outcome of surgical intervention on the flow and airway resistance can guide the surgeon in choosing an effective surgical strategy. Computed tomography images spanning the respiratory tract of an adult patient with a combined glottic and subglottic stenosis are used to reconstruct three-dimensional geometrical models of the airway. Computational fluid dynamics is used to obtain airway flow patterns during inspiration and expiration in these models. Numerical predictions about flow velocity, pressure distribution on the airway lumen, wall shear stress, and airway resistance are obtained so that the relevance of each individual stenotic level is quantified. Four different virtual surgeries in different combinations are assessed in order to remedy the constricted airway. The virtual surgery based airway models are evaluated by comparisons with the pre-treatment flow modeling results. The predicted numerical data revealed that the removal of the constriction at the level of the vocal folds will have the most significant effect on the airway resistance. The flow simulations offer a quantitative method of evaluating the airway resistance in patients with combined glottic and subglottic stenoses. Predictions of airway resistances and other numerical calculations from different virtual surgeries give additional inputs for the surgeon, in deciding the most appropriate surgery on a case-by-case basis., (Copyright © 2013 Elsevier Ltd. All rights reserved.)