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The experimental simulation between the composite hydraulic structure and the found obstacles in the downstream region is a challenging process due to the energy losses and kinematic dissipation. The current work focuses on a comparative analysis of free flow conditions that exist without obstacles and submerged flow conditions that occur due to obstacles. It indicates the evaluation of hydraulic variables and geometrical variables of composite hydraulic structure for both flow conditions. In addition, it includes an investigation of the interaction among these variables. The hydraulic variables include actual discharge, flow velocity, flow cross-sectional area that crosses the gate, downstream water depth, discharge coefficient, Reynolds number and, Froude number, while the vertical distance between the weir and gate represents the geometry variable. The interference between the weir discharge and gate discharge plays a significant role in the result fluctuation and variation for both flow conditions, while the form and size of the obstacles only have a major effect on the submerged flow. For both flow conditions, the water depth is investigated; there would be a drastic increase in water depth by using obstacles in the downstream area as compared with not using the obstacles. This study adopts different obstacles in shape and size, therefore, the variation of maximum and minimum water levels related to the location will occur. [ABSTRACT FROM AUTHOR]

Existence obstacles in terrain area and the mobility of the nodes in the network are the vital constrains that degrade the performance in Mobile Adhoc Network (MANET). To diminish the effect of such obstacles and mobility on the performance of MANET, the protocol used for routing must be efficient enough to handle both the factors. In the present work, we have considered the issues of Mobility and obstacle aware multipath communication in MANET. For avoiding obstacles, DeCasteljau Algorithm with Bezier curve concept has been applied. To the minimize impact of mobility, a speed based mobility prediction concept is used. Here optimal routing path across the obstacle is selected depending on its mobility prediction indicator, link duration, network connectivity and path availability. The performance of the suggested protocol is evaluated with Network Simulator-2. Simulation results confirm that the suggested protocol minimizes average energy consumption, network overhead, average delay and improves data deliverance in MANET.

The purpose of this study is to identify obstacles and success factors evident from empirical studies affecting strategy implementation and to provide an overview of the empirical literature. A systematic literature review (SLR) was used to analyze thirty-five peer-reviewed empirical articles. All of the 35 research papers selected in this review use primary data gathered from the organizations studied. This study of empirical research has identified 16 obstacles that can hinder strategy implementation and 18 success factors that can facilitate implementation. This study highlights factors that are dualistic, meaning that they contain both elements of obstacles and key success factors. The dualistic factors should therefore be considered in the strategy implementation process. Research gaps are identified. They include lack of studies on how to overcome obstacles to strategy on the one hand and on employee influence on implementation on the other. The differences among industries, countries, or cultures regarding implementation have not yet been explored at any depth. The paper adds to theoretical and practical knowledge based on the systematic overview it provides on strategy implementation from 1980 until 2020. The paper enriches the practical knowledge relevant to those implementing strategies, as it captures and identifies the dualistic factors affecting strategy implementation.

Wind energy is becoming one of the most widely used renewable energy sources in Romania as well. In order for production to be efficient and implicitly profitable, wind turbines are usually arranged in wind farms. The main purpose of the paper is to present intelligent criteria and tools for designing wind turbines. In the present study, the following are pointed out as topics of interest: the shading of the wind given by an obstacle, the height of the turbine hub, the distance between the obstacle and the turbine, the roughness class of the turbine location, the height and width of the obstacle and the porosity of the obstacle. These elements help to determine the variation of the wind front, the power of the wind captured by the turbines and the calculation of the energy captured. The results obtained using calculation programs are: wind speeds are in the range of 5-10 m / s in the predominant direction S-SE (between 2700 -3300) and V-NV (between 1500 -2100); power density function; Weibull distribution for wind speed; turbine power curve; Wind turbulence in the turbine area; power coefficient depending on wind speed; The amount of energy that the wind transfers to the rotor; Wind frequency curve; speed insurance curve. Finally, by using the modelling tools in Math Lab Simulink, the random speed distributions were obtained, which can be analyzed and then provided to obtain a maximum power, and consequently a maximum amount of energy. [ABSTRACT FROM AUTHOR]

Self-licensing and self-cleansing effects represent two aspects of the same self-regulatory mechanism that is based on the decision-making process. Building upon this background, the link of self-licensing with goal-oriented behaviour as one of the ways how self-regulation is explained is evident. In goal-directed behaviour, we perceive the maladaptive function of self-licensing as a possible obstacle causing a crisis in goal achievement, or the adaptive way how to resolve the self-regulatory conflict. In an action crisis, one considers several options - achieving the goal at all costs, giving up the effort to achieve it and identification of the alternative one. The objective of the study was the experimental examination of the relationships between self-licensing and self-cleansing, action crisis, goal disengagement and goal reengagement as two possible strategies for advancing the goal achievement process. The study was conducted on 195 participants divided into three conditions - self-licensing, self-cleansing and control group. The results did not show significant differences in action crisis, goal disengagement and goal reengagement between groups. The action crisis and goal disengagement were significantly more likely experienced while dealing with a subjective obstacle. Also, women were significantly more prone to goal reengagement than men. [ABSTRACT FROM AUTHOR]

Background: Overweight and obesity are significant global health concerns that involve deficits in gait and balance that affect daily activities. Although much is reported about the effect of overweight and obesity on gait during unobstructed walking, not much is known about how overweight and obesity could impact gait under more challenging conditions, such as environments with obstacles. Objective: The aim of this study is to systematically review and synthesize the available data regarding the effects of overweight and obesity on obstacle crossing during walking. Methods: This review will follow the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. PubMed, Web of Science, Scopus, and SPORTDiscus will be systematically searched with no limitations on publication date. Only full-text English-language articles published in a peer-reviewed journal will be included. Included articles must have compared obstacle crossing during walking in individuals with overweight or obesity to individuals of normal body weight. A total of 2 independent reviewers will select the articles and extract the following 4 sets of data: (1) study characteristics, (2) sample description, (3) obstacle crossing task protocol, and (4) main results obtained. If a considerable number of homogeneous papers are included, a meta-analysis will be conducted. A preliminary search was conducted in November 2021. Results: The results will include the article selection flowchart as well as tables and figures synthesizing the extracted data on the effects of overweight and obesity on obstacle crossing during walking. The preliminary search identified 73 original records, of which 5 articles met the inclusion criteria. Conclusions: This review will present researchers and clinicians with an overview of published studies that have compared the performance of obstacle crossing for individuals with overweight and obesity to those of normal body weight. Gaining insight into the control strategies adopted by individuals with overweight and obesity is critical for safe and successful obstacle crossing in this population. We therefore believe that our findings could be useful for identifying people at risk of falls and developing and implementing fall prevention programs for individuals with overweight and obesity. [ABSTRACT FROM AUTHOR]

We present a new approach to optimal design with state constraints based on active set optimization theory and implement it using a phase-field model. Our primary focus is on compliance minimization subject to inner and outer obstacles. We compare our approach to a classical penalization method and study the influence of initial guess, penalization parameters, and discretization. [ABSTRACT FROM AUTHOR]

Abstract Porcine circovirus type 3 (PCV3) is a novel circovirus identified in sows with PDNS-like clinical signs and reproductive failure. The capsid protein (CAP) of PCV3 is expected to be an effective vaccine candidate. Here, we expressed the original capsid protein, truncated capsid protein without anterior highly repetitive arginine (ΔCAP) and their codon-optimized counterparts in E. coli. These results showed that lots of repeated arginine could severely lower the expression of PCV3 capsid protein in E. coli. At the same time, the recombined truncated PCV3 capsid protein forms typic virions. The efficient expression of capsid protein is expected to serve the development of PCV3 vaccines and other studies of PCV3 capsid protein.

Underground structures are normally located in highly-confined and congested spaces, which may lead to severe gas explosion accidents, with significant human and economic losses. For accurately evaluating the consequences of these explosions, a variety of influencing factors need to be considered, including concentrations of gas mixtures, vent conditions, obstacles, and ignition features. Moreover, a good review on these influencing factors is important for a better understanding of explosion behavior, e.g., the deflagration to detonation phenomenon. In this study, some critical influencing factors for gas explosions in underground or confined spaces are investigated, and the effects of the factors on such gas explosions are examined. The results are discussed, along with findings from literature. The present study provides a reference for future studies on safety management and consequence mitigation for underground gas explosions.

Experimental investigations are carried out to study the physics of the flow that passes weir-gate hydraulic structure and encounters obstruction with or without installation of downstream opening. This study approaches the comparison between two different options; the first option deals with free flow condition while the second option deals with submerged flow condition. Various cases are performed considering different hydraulics variables and dimensions variables to evaluate the existence of obstruction with or without openings. Overall the flow pattern is more sensitive to the presence of obstruction at downstream region than in its absence. The hydraulic variables that are considered in the study are divided into dimensional variables such as discharge, downstream flow velocity and water depths at downstream and non-dimensional variables such as discharge coefficient, Froude number and Reynolds number. The obstacles which are used in this study have variable heights with constant width and length. Constant spacing between the obstacles is adopted. Different arrangements of obstacles are considered in this study and it is found that a significant and reasonable result is different among the cases. The effect of rectangular opening in the obstruction on flow pattern is studied. The effect of obstacles with rectangular opening gives a noticeable result in the assessment of the discharge coefficient of the composite hydraulic structure.

In this study, teacher candidates were asked to evaluate activities designed with the use of the history of mathematics (HoM) as a tool in terms of the obstacles to the use of the HoM. A total of 12 activities which used the HoM as a tool were utilized in the study. The study group consisted of 40 teacher candidates who were first-year students in an elementary mathematics education program. The activities were used within the HoM course. The presentation and implementation of all activities took six weeks. Then, 40 teacher candidates completed written opinion forms, and 10 of them got interviewed. As the collected data were analyzed, teacher candidates’ perceptions about whether each obstacle to the use of the HoM could emerge were identified. Afterwards, two different researchers examined the reasons underlying the identified perceptions.The findings showed that the activities used in this study could be used in mathematics classes and similar activities may stop the emergence of philosophical, student-related, stylistic and instructional preparation obstacles. . In the future, longer-term studies may be conducted with mathematics teachers and secondary school students with the activities used in this study. In this way, stronger evidence may be obtained about the effectiveness of using such activities in the instructional process.

In this paper, we propose four different numerical methods for solving the Non-Linear Shallow Water Equations (NSWE), which are used to study dam-break flow over an obstacle. The discrete equations are formulated by applying various finite difference methods with filter involving wet-dry procedure. To validate our numerical model, several benchmark tests are carried out. Comparison of the computed results with the analytical and experiment data shows that our numerical model reproduces the flow with high accuracy. Moreover, we examine the effect of the shape and dimensions of the obstacle on downstream water height. Rectangular obstacles reduce downstream water height more significantly than triangular and trapezoidal ones. Downstream water height decreases non-linearly as obstacle height and width are increased.

[Display omitted] It has been experimentally shown that a complex obstacle consisting of two confusers oriented in opposite directions of a cylindrical vessel completely prevents the propagation of diluted methane – oxygen flames, i.e. , the obstacle is the most effective flame arrester; the theoretical predictions are consistent with the experiments. [ABSTRACT FROM AUTHOR]

Background: The increased number of older adults living alone has created a substantial care need. However, the utilization rate of services and facilities to meet these needs are surprisingly low. Many of older adults experience difficulties accessing these services, although it remains unclear how these obstacles impede access to services. This study explored the obstacles and difficulties experienced by urban older adults in seeking community care.Methods: A phenomenological study was carried out and participatory observation and in-depth interviews were employed to investigate the process of seeking care of older adults in urban communities. A total of 18 urban community-dwelling older adults aged 75 years and over were included. Data collected were analysed by content analysis.Results: We identified the pathways by which senior-only households sought community care and encountered obstacles. (1) lack of community care information: older adults did not know where and how to get services, even though the care institutions scattered throughout the community; (2) limited mobility: older adults often suffered from various chronic diseases, which physically hindered their access to care resources; (3) complex process of achieving care: the functional fragmentation and geographical dispersion of care institutions made the care-seeking process challenging and confusing for older adults; (4) incomprehension of needs expression: limited interaction time and communication barriers between staff of institutions and the older adults were the final obstacle. Only by surmounting these obstacles one by one can older adults access the care resources effectively.Conclusions: When older adults in the community initiated calls for help, they encountered several obstacles. Their physiological and social disadvantages limited their ability to seek care physically. Lack of integration and clear guidance in the process of providing community care exacerbated these difficulties. Reform of care services should focus on the visibility and accessibility of services for older adults. [ABSTRACT FROM AUTHOR]

The DCRFoam solver (density-based compressible solver) built on the OpenFOAM platform is used to simulate the reflection and diffraction processes that occur when detonation waves collide with various objects. Static stoichiometric hydrogen–oxygen mixtures diluted with 70% Ar are used to form stable detonation waves with large cells, with initial conditions of 6.67 kPa pressure and 298 K temperature. The diameters of the cylindrical obstacle range from 6 mm to 22 mm, with x = 230 mm, x = 244 mm, and x = 257 mm being the chosen position. Cylindrical, square, triangular, and inverted triangular obstacles are used, and the quenched detonation re-initiation processes behind them are investigated. In the detonation diffraction process, four triple points exist at the same time due to the effect of cylindrical obstacles of smaller diameters. The re-initiation distance of the detonation wave increases with the increase of cylindrical obstacle diameter. Both the Mach reflection angle and the decoupled angle decrease as the diameter increases. When the location of the cylindrical obstacles is changed, the detonation wave dashes into the obstacles with its different front structures, it is easier to realize the detonation re-initiation when the weak incident shock at the front of a detonation wave strikes the obstacles, and the re-initiation distance decreases by 17.1% when compared with the longest re-initiation distance. The detonation re-initiation distance is shortest under the action of cylindrical obstacles, however the quenched detonation cannot be re-initiated when the inverted triangle and square obstacles are used. The suppression effects of inverted triangle and square obstacles on detonation waves are more evident. • Diffraction and re-initiation of detonations with large cell were simulated. • The DCRFoam solver built on the OpenFOAM platform was used. • Detonation waves with different front structures strike obstacles were studied. • Obstacles with different shapes and sizes were employed in this study. [ABSTRACT FROM AUTHOR]

We propose to numerically study the dispersion of pollutants emitted from a chimney bent around an obstacle. A numerical simulation of the dispersion of pollutants emitted from a chimney has been performed using the CFD code Fluent. The influence of the ratio (R) of the jet speed to the lateral wind velocity, the distance between the chimney and the obstacle and the height of the obstacle on the dispersion of the ejected pollutants was studied. The numerical method used to solve the flow equations is a finite volume method, the mesh size adopted is non-uniform, very close to the chimney and around the obstacle. The results show essentially that the dispersion of the pollutants is more pronounced for larger R-ratios. It is also shown that the location and height of the obstacle modify the flow, the further the chimney is from the obstacle the greater the dispersion of pollutants. Also, ejection at a higher chimney height generates a larger plume which favours dilution and dispersion. [ABSTRACT FROM AUTHOR]

Hydrogen has been utilized in FCV and leakage can cause safety issues. In this study, the vehicle is simplified as a cuboid enclosure with obstacles. The influence of obstacle locations on the hydrogen diffusion behavior is investigated with the iso-surfaces of 1% and 4% volume fraction of hydrogen. The time of the iso-surface of 4% volume fraction to reach the ceiling and the sidewalls without any obstacles is 1.42 and 1.25 times of that with an obstacle, respectively. Both height and the width of the flammable zone in the enclosure with an obstacle are greater than that without obstacles. The distance between the obstacle and the leakage affects significantly the hydrogen diffusion and the influence of the obstacle on the hydrogen diffusion strengthens with the decrease of the distance. Yet as the distance keeps same, the obstacle position relative to the leakage has no significant effect on hydrogen diffusion, and it makes little effect difference whether the obstacle is located in front of leakage or side of leakage. • Iso-surfaces of 4% and 1% are studied to explore the behavior of hydrogen diffusion. • The influences of the obstacle with different location are compared. • The effects of the obstacle on hydrogen diffusion of each stage are discussed. [ABSTRACT FROM AUTHOR]

Heavy rain in a particular area can cause flooding in both the primary area and the surrounding area. A flood is an event where water is inundated in an area due to increased water volume. Due to high level of water and other hazards arising from flooding, flood victims need to move to a location prepared for evacuation. To get to that location prepared, the victims must get through a safe route. Searching for safe evacuation routes is important to save flood victims and bring them to the evacuation centre safely. Search for evacuation routes related to obstacles on the road to get through. Slippery roads, high puddles of water on the roads, rivers that are located close to the roads that flood victims will have to get through, drainage of waterways and the vulnerability of victims are taken into consideration in choosing a route to get to the evacuation location. There are several problems in choosing a safe route: (1) how to take into account the obstacles on the road to be passed (2) how to choose the priority of the route to be passed with the obstacles encountered. The proposed solution to deal with the problems encountered are (1) to take into account road obstacles by giving the obstacle weights. Fuzzy logic is used to calculate the value of obstacle weights (2) the problem of selecting route priorities will be solved using the firefly algorithm. The firefly algorithm is an algorithm inspired by the social life of fireflies. The priority route for evacuation of flood victims is sought using the method proposed in this study which is the optimal route. The optimal route referred to in this study is the route that has the smallest obstacle weight value. The simulation results show that the fuzzy logic integrated into the firefly algorithm (FuFA) provides a safe route priority, indicated by the smallest obstacle weight value. [ABSTRACT FROM AUTHOR]

Nan province, the biggest cultivation area of fresh mulberry fruit in Thailand is located in four districts: Chaloem Phra Kiat, Bor Klua, Tha Wang Pha, and Wiang Sa. The production yield of mulberry is about 848.6 kg/acre/year; however, it is mostly sold as frozen product. The Queen Sirikit Department of Sericulture intends to develop a new marketing channel for fresh mulberry fruit. The present study was to explore the current situation of mulberry fruit supply chain management in Nan province and to propose a new supply chain model for fresh mulberry. To gather information about supply chain management, the supply chain operation reference (SCOR) model was utilized to investigate four members of the mulberry supply chains, including growers, primary middlemen, secondary middlemen, and customers. The SCOR model possibly identifies critical points in the current supply chain and five obstacles in the distribution of fresh mulberries that are improperly handled, affecting market channels and product quality due to a lack of suitable knowledge and technology for postharvest handling. Active packaging technology of fresh mulberries from a previous study was introduced to design a new supply chain model, and it was found that this technology could extend the product’s shelf life and preserve its freshness. Although the cost of the active packaging technology leads to a much higher cost on the newly developed supply chain compared to that of the traditional supply chain, the developed model could enhance new market channels, including selling prices, and provide growers with more benefits than the traditional supply chain. [ABSTRACT FROM AUTHOR]

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This paper aims to present a numerical study of dam break flow in the presence of an obstacle. A model based on the modified Non-Linear Shallow Water Equations with cross section and a dispersive treatment was solved numerically using a momentum-conservative finite volume method on a staggered grid. To validate the numerical model, several benchmark tests were carried out. Comparison of the computed results with the analytical and experimental data shows that the numerical model here proposed the flow with high accuracy. Moreover, the effect of the obstacle’s dimensions on the water height was examined. The extension to different contraction geometries of the simulation channel was examined.

Flame acceleration and the deflagration to detonation transition (DDT) are important physical phenomena in combustion theories. The main objective of this work is to provide a comprehensive understanding of the effect of the positions of obstacles when a flame propagates in obstructed confined channels, using two-dimensional direct numerical simulations (DNSs) with the detailed chemical kinetics mechanism of H2. The underlying mechanism for the flame propagation and detonation, affected by the obstacles with the flame-shockwave and flame–vortex interactions, is investigated. In 1000 K cases, two different detonation modes associated with flame propagation are observed, where for the case with obstacles near the ignition kernel, autoignition takes place in the end-gas region as predicted, while for the case with obstacles far away from the ignition kernel, autoignition occurs, instead, in front of the flame and triggers a DDT immediately. Both of two modes consist three processes: flame propagation stages, flame-pressure wave/shockwave interaction, and detonation development. The evolutions of centerline temperature and pressure are employed to explicitly demonstrate the detonation process. The differences in the shockwave formation, peak temperature, and pressure values can be clearly observed. The mechanisms of the different detonation modes induced by different obstacle positions are analyzed in detail for the first time. The results indicate that the compressed and preheated temperature of the unburned mixture determines the detonation combustion mode. The conclusion is further proved in the flame-shockwave number variation and detonation modes transition when initial temperature is changed. This study will provide new insight into the DDT and detonation phenomena in engines. [ABSTRACT FROM AUTHOR]

To investigate the actual gas explosion and propagation laws in the roadway of an underground mine, experiments were conducted in a standard 19-L tube of rectangular section to provide a comprehensive understanding of the effects of carbon monoxide (CO) addition and obstacles placed on the flame propagation of explosions from methane–air mixtures at different conditions. The flame structure, flame propagation speed, heat loss, and explosion pressure were used to reflect the explosion behaviors of the premixed flame. The experimental results indicate that the enhancement and attenuation of the explosion pressure wave are significantly influenced by an obstacle. The existence of obstacles changed the trend of classical pressure rise, thus forming a first pressure peak. In addition, the position close to the obstacle presented a higher explosion pressure. Under 7 vol.% and 9.5 vol.% CH4 conditions, the increase of CO (from 0 vol.% to 2 vol.%) promoted explosion flame propagation. However, the CO exhibited a clear negative effect on the rate of flame propagation due to exacerbated O2 depletion of 11 vol.% CH4, and the negative effect enhances with CO increased. Besides, when the CO addition increased, the flame tended to more instability and more brightly. For heat loss, with the increase of CO content in mixed gases, there was a slight promoting, constant and inhibiting effect for 11 vol.%, 9.5 vol.%, and 7 vol.% CH4, respectively. These results are of fundamental importance for the prevention and mitigation of gas explosion in underground mines and other industrial scenarios. [ABSTRACT FROM AUTHOR]

To address the coal gangue fracture heat transfer problem, the law of heat transfers and temperature distribution in the coal gangue fracture is studied. The temperature distribution in a coal gangue fracture under 12 conditions (with or without the obstacle, and various heat flows) is simulated via Fluent numerical simulation. The results show that the heat flow velocity, temperature and obstacle are important factors in inhibiting heat transfer oxidation spontaneous combustion in the coal gangue fracture. When the heat flow temperature is constant, the low-velocity heat flow causes a large temperature drops in the coal gangue fracture; when the heat flow velocity is constant, the high-temperature heat flow also produces a large temperature drops effect; when the obstacle is present and the heat flow produces vortex pass through the obstacle, increasing the energy loss in the coal gangue fracture, causing the temperature in the coal gangue fracture to drop rapidly, and reach the lowest in the position of the obstacle. Obstacles can effectively inhibit the heat transfer characteristics in the coal gangue fracture and reduce the risks of oxidation spontaneous combustion of gangue after grouting. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW), as an additive manufacturing method, can effectively mould ceramic parts. The single screw extruder is used here to extrude viscous SiC slurry. The deposits caused by the low viscosity and the agglomerations resulting from the nonuniform mixing, form the obstacles in the channel, which affect the normal theoretical flow of the slurry, and interaction with other printing parameters. Therefore, it is necessary to explore the effect mechanism of the obstacles on the flow. The obstacles are always irregular, which makes it difficult to directly analyse them. The irregular geometries are always composed of linear and/or arcuate elements; therefore, the obstacles can be simplified into regular geometries. In the previous work, linear elements have been analysed first. As the continuous work, arcuate elements are investigated in the current research. To conduct the required simulations, an improved MRT LBM (multiple relaxation time lattice Boltzmann method) with a pseudo external force is proposed. The above numerical method is combined with the rheological model to analyse cases with two obstacles, and the obtained results are used to reveal the general mechanism in cases with multiple obstacles. The results show that the central angles, radii, and positions of the obstacles are important factors affecting the flow. To obtain a stable and controllable slurry flow, it is recommended that the central angle and the radius should be small enough. The number of obstacles should be minimized, and the position of the last obstacle is expected to be far away from the outlet to avoid the negative velocity. In addition, the adjacent obstacles should maintain a certain distance to ensure the full development of the vortex and avoid affecting the following obstacles or back vortices. [ABSTRACT FROM AUTHOR]

Copyright of Transactions on Aerospace Research is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Direct ink writing (DIW) provides a new way to mould ceramic parts. When a single screw extruder is used to extrude SiC slurry, the deposits caused by low viscosity and the agglomerations resulting from the nonuniform mixing, form the obstacles in the channel, which affect the normal flow of the slurry, theoretical outlet velocity, and interaction with other printing parameters. Therefore, it is necessary to study the mechanism responsible for the effects of the obstacles on the flow. The obstacles are always irregular, which makes it difficult to directly analyse them. Irregular geometries are always composed of linear and/or arcuate elements; therefore, the obstacles can be simplified into regular geometries. In the present work, linear elements are analysed first. Then, an improved MRT LBM (multiple relaxation time lattice Boltzmann method) with a pseudo external force is proposed for the flow analysis. The improved MRT LBM is combined with rheological test data to investigate cases with two obstacles, and the results are applied to reveal the general mechanism in cases with multiple obstacles. The results show that the angles, sizes, and positions of the obstacles are three important factors influencing the flow. To obtain a stable and controllable slurry flow, it is recommended that the first angle θ 1 be an acute angle. In addition, the number of obstacles should be minimized, and the position of the last obstacle should be far away from the outlet. [ABSTRACT FROM AUTHOR]

In this paper we study a class of quasi-variational-hemivariational inequalities in reflexive Banach spaces. The inequalities contain a convex potential, a locally Lipschitz superpotential, and a implicit obstacle set of constraints. Solution existence and compactness of the solution set to the inequality problem are established based on the Kakutani–Ky Fan fixed point theorem. The applicability of the results is illustrated by the steady-state Oseen model of a generalized Newtonian incompressible fluid with mixed boundary conditions. The latter involve a unilateral boundary condition, the Navier slip condition, a nonmonotone version of the nonlinear Navier-Fujita slip condition, and a generalization of the threshold slip and leak condition of frictional type. [ABSTRACT FROM AUTHOR]

The present work aims to investigate the recirculation and incipient mixing zones in a channel flow supplied with obstacles. The main objective is to develop a new technique to control these recirculation zones by setting a variable roughness. For the purpose of varying that roughness, 4 small bars of heights 0.25H, 0.5H, 0.75H and H were placed downstream of the obstacle; H is the height of the obstacle. For this, a three-dimensional numerical approach was carried out using the ANSYS CFX computer code. In addition, the governing equations were solved using the finite volume method. The K-γ shear-stress transport (SST) turbulence model was utilized to model the turbulent stresses. In the end, we presented the time-averaged simulation results of the contours of the current lines (3D time-averaged streamlines, trace-lines), three components of the velocities: (velocity u contour), (velocity v contour) and (velocity w contour), trace-lines, stream ribbons and mean Q-criterion iso-surface. [ABSTRACT FROM AUTHOR]