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The flow and thermal breakthrough phenomenon in a forced external circulation standing column well (FECSCW) directly affects heat transfer efficiency and load-carrying capacity. A numerical model for FECSCW is developed to analyze the migration of the temperature and velocity front under the flow and thermal breakthrough. The results indicated that thermal breakthrough began after simulation running 2.5 min and was completely formed after 12 min. The inlet water, which directly entered the production well without heat exchange with the aquifer, accounted for 12.8%. When the porosity of the backfill material decreased from 0.35 to 0, the coefficient of performance (COP) of the heat pump unit increased by 1.6% on average, and the thermal breakthrough strength decreased by an average of 45.3% within 25 min. Where seepage velocity near the well wall was greater than 1 × 10−3 m•s−1, faster velocity front migration was observed, while the migration advantage of the temperature front was more prominent outside of this region. Through quantitative analysis of flow and thermal breakthrough, temperature and velocity front migration, and COP change of heat pump unit, theoretical suggestions were provided for the thermal transfer mechanism near the thermal well wall. The extended research in this study can be applied to the design and optimization of forced external circulation standing column well system.

This study aims to investigate variability of the deep South China Sea (SCS) circulation using the Hybrid Coordinate Ocean Model (HYCOM) global reanalysis product. The results reveal that annual cycle is a dominant component in the deep SCS circulation. Meanwhile, the boundary circulation strength is the weakest in January and peaks between June and September. The eastern and southern boundary currents strengthen and weaken one to three months earlier than that of the western and northern boundaries. Vector Empirical Orthogonal Functions (VEOF) analysis results reveal that semiannual and intraseasonal fluctuations are significant components, of which the spatial patterns are mainly confined in the northern and western boundary areas as well as the southwestern sub-basin. Wavelet analysis results show the strength of significant fluctuation varies year to year. Trend analysis results indicate a decadal weakening in the deep SCS circulation. An anomalous anticyclonic circulation, 50–70 km apart from the slope break, tends to weaken the cyclonic boundary circulation in the western and northern boundaries as well as the southwestern sub-basin. This trend is similar to the observed decadal weakening in the Northern Atlantic deep circulation. Thus, the findings of this study reveal that the variability of the deep SCS circulation has a remarkable response to the climate change. The mechanisms responsible for the variability are worth pursuing if more observations are available.

The influence of El Niño Southern Oscillation (ENSO) and the Stratospheric Polar Vortex (SPV) on the zonal asymmetries in the Southern Hemisphere atmospheric circulation during spring and summer is examined. The main objective is to explore if the SPV can modulate the ENSO teleconnections in the extratropics. We use a large ensemble of seasonal hindcasts from the European Centre for Medium-Range Weather Forecasts Integrated Forecast System to provide a much larger sample size than is possible from the observations alone.We find a small but statistically significant relationship between ENSO and the SPV, with El Niño events occurring with weak SPV and La Niña events occurring with strong SPV more often than expected by chance, in agreement with previous works. We show that the zonally asymmetric response to ENSO and SPV can be mainly explained by a linear combination of the response to both forcings, and that they can combine constructively or destructively. From this perspective, we find that the tropospheric asymmetries in response to ENSO are more intense when El Niño events occur with weak SPV and La Niña events occur with strong SPV, at least from September through December. In the stratosphere, the ENSO teleconnections are mostly confounded by the SPV signal. The analysis of Rossby Wave Source and of wave activity shows that both are stronger when El Niño events occur together with weak SPV, and when La Niña events occur together with strong SPV.

Wind tunnel testing is conducted on a NACA0015 airfoil with a rounded trailing edge, known as a circulation control airfoil, at the chord Reynolds number of 1.10×105 and at the angles of attack of ...

The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically. We show that, under thin airfoil assumption and for potential flow, the transit time difference is equal to the circulation divided by the square of the inflow velocity and the lift coefficient is equal to half of the number of chords travelled by the airfoil during the transit time difference. An analysis of transit time difference for very thick airfoil (c.f. very large angle of attack) suggests the transit time may change sign beyond thin airfoil assumption, a conclusion supported by an example of flow with an attached vortex. Thus, fluid particles may transit the upper surface with less, equal and more time than those transiting the lower surface for lift producing airfoils, depending on the configuration of flow structure and geometry.

BACKGROUND: Vascular changes in liver fibrosis can result in increased intrahepatic vascular resistance and impaired blood circulation. This can hinder the recovery from fibrosis and may eventually lead to portal hypertension, a major cirrhosis complication. This report proposed a volume-averaged Murray’s deviation method to characterize intrahepatic circulation in the liver during fibrosis and its subsequent regression via X-ray phase-contrast computed tomography (PCCT). METHODS: Liver fibrosis was induced in 24 Sprague-Dawley rats by exposure to carbon tetrachloride (CCl(4)) for up to 10 weeks, after which, spontaneous regression commenced and continued until week 30. High-resolution three-dimensional (3D) imaging of the livers was performed with PCCT. The values of Murray’s deviation based on the volume-averaged and the conventional diameter-based methods were compared. After that, the intrahepatic circulation at different stages of fibrosis was evaluated using the volume-averaged method. The increase in collagen during liver fibrosis was assessed by pathological analyses. RESULTS: A comparison of the 2 methods showed that with an increase in the number of diameter measurements, the value of Murrary’s deviation obtained using the diameter-based method gradually approaches those of the volume-averaged method, with minimal variations. The value of Murray’s deviation increased with the development of fibrosis. After reversal, the value rapidly decreased and approached that of the normal state in both the main branches (1.05±0.17, 1.17±0.21, 1.34±0.18, and 1.17±0.19 in the normal, moderate, severe, and regressive groups, respectively; P

Dynamical mechanisms for the summer Eurasian circulation trend pattern are investigated by analyzing reanalysis data and conducting numerical model simulations. The daily circulations that resemble the Eurasian circulation trend pattern are identified and categorized into two groups based on surface warming signal over central and eastern Europe. In the group with large warm anomaly, the upper-level circulation takes on a wave packet form over Eurasia, and there are enhanced latent heating anomalies centered over the North Sea and suppressed latent heating anomalies over the Caspian Sea. The numerical model calculations indicate that these latent heating anomalies can excite an upper-level circulation response that resembles the Eurasian circulation trend pattern. Additional analysis indicates that trends of these two latent heating centers contribute to the long-term circulation trend. In the weak warm anomaly group, the circulation pattern takes on a circumglobal teleconnection (CGT) pattern, and there is no heating signal that reinforces the circulation. These results indicate that not all CGT-like patterns excite temperature anomalies that are persistent and in phase with the trend pattern, and that quasi-stationary forcings, such as the latent heating anomalies, play an important role in driving the boreal summer circulation anomaly that accompanies the strong and persistent surface temperature signal.

The topographic dynamical effect from Eurasia (EA_Topo) and North America (NA_Topo) on the winter isentropic meridional mass circulation (IMMC) is investigated using the WACCM. The independent effect of EA_Topo and that of NA_Topo, with the former much stronger, are both to strengthen the IMMC that is composed of the lower equatorward cold air branch (CB) and the upper poleward warm air branch in the extratropical tropopshere (WB_TR) and stratosphere (WB_ST). Further investigation of the individual contributions from changes in stationary vs. transient and zonal-mean flow vs. waves reveals that, due to the topography-forced mass redistribution, changes in the low-level meridional pressure gradient force a zonal-mean counter-clockwise/ clockwise meridional cell in the southern/northern side of topography. This weakens/strengthens the IMMC south/north of 30°N from the troposphere to lower stratosphere, acting as a dominant contributor to the IMMC changes south of 50°N. Meanwhile, the EA/NA_Topo-forced amplification of stationary waves constructively interacts with those determined by land-sea contrast, making the dominant/minor contributions to the strengthening of CB and WB_TR north of 50°N. The related increase in the upward wave propagation further dominates the WB_ST strengthening in the subpolar region. Meanwhile, transient eddy activities are depressed by EA/NA_Topo along with the weakened background westerly, which partly-offset/dominate-over the contribution from stationary flow in midlatitudes and subpolar region. The coexistence of the other topography (NA/EA_Topo) yields destructive mutual interferrence, which can weaken/offset the independent-EA/NA_Topo-forced meridional mass transport mainly via changing the zonal-mean as well as the downstream wave pattern of mass and meridional wind.

Vortex rings are turbulent coherent structures that are ubiquitous in various application domains ranging from gas turbines to aquatic locomotion. The vortex rings are highly sensitive to a variety of external governing parameters. In this paper, we have quantitatively investigated the topology and formation mechanisms of such rings under the effect of externally modulated temperature, pressure, and amount of fluid injection. Vortex characteristics like translational velocity, peak vorticity, and circulation are analytically predicted along with rigorous experimental corroboration. The experiments are carried out on high viscous fluids with circulation-based vortex Reynolds number varied in the range of 8–100.​ The rings under distinct conditions are generated from a solenoid valve-controlled pipe by varying the externally governed parameters. We have shown that these parameters can be collapsed into a universal variable to provide insights into the vortex roll-up characteristics and variation of energy distribution towards translation and circulation for a given vortex ring.

The given article considers results of experimental measurements, productivity comparison and master controller executive system of flat-plate solar collector with thermosiphon circulation and flat solar collector with special chemical coating. There has been developed master controllers control module, which receives data from temperature and lighting sensors, obtained in operation process. The aim of the research is getting the solar collectors? optimal parameters, representing maximal usage performance index, controllability, as well as, construction type, allowing energy saving. In the recent years flat-plate solar collectors with chemical coating are characterized with higher efficiency in real conditions usage. The developed master controllers? executive system is used for monitoring the installation?s main parameters, as well, it permits to compare characteristics of solar collector with thermosiphon circulation those of flat-plate solar collector with chemical coating. The obtained experimental data has shown, that flat solar collectors, using chemical coating as a transfer medium in solar heat supply system, have an advantage in the context of usage effectiveness. The heat output and water heating in a flat solar collector are calculated, which vary depending on the intensity of solar radiation. The thermal efficiency of a flat solar collector with a thermosiphon tank based on the Mojo V3 platform using Dallas sensors is calculated.

We report three cases in which endovascular treatment (EVT) was performed for anterior circulation large vessel occlusion (LVO) beyond 24 h from the onset of stroke. Case 1 experienced left hemispatial neglect and gait disorder due to right internal cerebral artery (ICA) occlusion and underlying atherosclerosis. After percutaneous transluminal angioplasty (PTA), revascularization with mild stenosis was achieved. Case 2 complained of reduced activity, motor aphasia, and right-sided hemiparesis due to left middle cerebral artery occlusion. After thrombectomy using a retrieval stent, revascularization with M1 stenosis and distal perfusion delay was observed, which improved after PTA. Case 3 arrived at our hospital 30 h after the onset of dysarthria and gait disturbance due to left ICA occlusion. Since the symptoms were mild, medical treatment was started; however, the patient's symptoms deteriorated 6 h later, and EVT was required. After thrombectomy using a retrieval stent, revascularization was achieved. LVO pathophysiology beyond 24 h of stroke onset varies and may require multimodal treatment. Preserving the pyramidal tract may lead to favorable outcomes, even in cases of anterior circulation LVO. EVT may be effective for anterior circulation LVO because, in some patients, infarct volume continues to increase >24 h after stroke onset.

The effects of operating pressure on the gas–solid flow characteristics in a pressurized circulating fluidized bed (CFB) gasification system were studied by experiment and simulation. Elevated operating pressure was found to increase the particle uniformity in the axial and radial directions. Experiments and simulations both showed that as the operating pressure increased, the pressure drops along the riser height decreased. The experimental pressure drops at the same locations decreased when the operating pressure increased, but the opposite trend was observed in the simulation results. A proper drag model must be developed for the accurate simulation of pressurized CFB operation, and the accuracy of electrical capacitance tomography (ECT) measurement and cross-correlation analysis should be improved for better prediction of the particle circulation flux.

In this study the multiphase particle-in-cell (MP-PIC) method is used for the simulation of two pilot-scale circulating fluidized beds (CFBs) with quartz sand belonging to Geldart’s group B as bed material. The simulations were performed using a homogeneous drag model as well as a structure dependent drag model based on the energy minimization multi-scale method (EMMS). The results are compared with experimental data from literature as well as experiments. The simulations with the EMMS based drag model show a good agreement of the time-averaged axial solids concentration, circulation rate and riser pressure drop. Furthermore, a lower grid sensitivity is observed compared to the homogeneous drag model. In contrast to the conventional drag model a dense bottom zone is predicted by the EMMS based drag model. An overprediction of the solid concentration in the dense bottom zone is presumably due to an overprediction of the cluster diameter that is calculated using an empirical cluster diameter correlation. This shows the necessity for a new meso-scale cluster correlation for the simulation of Geldart B particles. Furthermore, the results of the time-averaged radial solids concentration differ from the expectations of a core-annulus flow indicating that a mesh refinement at the walls is necessary. Finally, the importance of using a realistic particle size distribution is identified.

The Weddell Sea supplies 40%–50% of the Antarctic Bottom Water that fills the global ocean abyss, and therefore exerts significant influence over global circulation and climate. Previous studies have identified a range of different processes that may contribute to dense shelf water (DSW) formation and export on the southern Weddell Sea continental shelf. However, the relative importance of these processes has not been quantified, which hampers prioritization of observational deployments and development of model parameterizations in this region. In this study a high-resolution (1/12°) regional model of the southern Weddell Sea is used to quantify the overturning circulation and decompose it into contributions due to multiannual mean flows, seasonal/interannual variability, tides, and other submonthly variability. It is shown that tides primarily influence the overturning by changing the melt rate of the Filchner–Ronne Ice Shelf (FRIS). The resulting ∼0.2 Sv (1 Sv ≡ 106 m3 s−1) decrease in DSW transport is comparable to the magnitude of the overturning in the FRIS cavity, but small compared to DSW export across the continental shelf break. Seasonal/interannual fluctuations exert a modest influence on the overturning circulation due to the relatively short (8-yr) analysis period. Analysis of the transient energy budget indicates that the nontidal, submonthly variability is primarily baroclinically generated eddies associated with dense overflows. These eddies play a comparable role to the mean flow in exporting dense shelf waters across the continental shelf break, and account for 100% of the transfer of heat onto the continental shelf. The eddy component of the overturning is sensitive to model resolution, decreasing by a factor of ∼2 as the horizontal grid spacing is refined from 1/3° to 1/12°.

In grazing ecosystems, mature seeds fall directly to the soil to form the soil seed bank (SSB), or are ingested by grazing livestock to become part of the dung seed bank (DSB; i.e., seed circulation). Both the SSB and DSB form the basis for the natural regeneration of vegetation. However, little is known about the relationships between the SSB, DSB, and aboveground vegetation (AGV) community under different stocking rates (SRs). This study investigated the relationships between the SSB, seeds in Tan sheep (Ovis aries) dung, and AGV at different SRs (0, 2.7, 5.3, and 8.7 sheep ha–1) in a semiarid region of the Loess Plateau in China. We found that Tan sheep grazing increased the species richness heterogeneity of grassland vegetation, and negatively influenced the density of AGV. Under natural conditions, 17 species from soil‐borne seeds and 10 species from Tan sheep dung germinated. There was low species similarity between the soil and DSBs and AGV. Sheep SR and the seed banks (soil and dung) were negatively correlated with AGV. Seeds are cycled from herbage to livestock to soil during cold season grazing; the seasonal nature of this seed dispersal is an adaptation to harsh, semiarid environments. Increased seed bank diversity under sheep grazing facilitates grassland regeneration on the Loess Plateau, similarly to other semiarid regions globally., Mature seeds can fall directly onto the soil to form the soil seed bank or become part of the dung seed bank through livestock grazing. Seeds in the feces eventually are incorporated into the soil, contributing to the soil seed bank. Seed cycling was depressed at higher grazing intensities. Sheep grazing disturbance increases the diversity of seed banks and assists in the propagation and regeneration of vegetation on the Loess Plateau and in other semi‐arid regions of the world.

Using delayed detached-eddy simulations, the objective of this paper is to show the effects of some design parameters on the wake recovery of vertical-axis turbines. To that end, the wake dynamics of a single-blade turbine is analyzed and compared for two different positions of blade attachment point and for two designs of blade support structures (struts). The results show that the chordwise position of the blade attachment point affects the temporal evolution of the blade circulation during the turbine revolution. More precisely, we demonstrate that an attachment point positioned near the trailing edge of the blade leads to a temporal vorticity distribution that is detrimental to the wake recovery. Moreover, we show that the use of tip struts, that are highly beneficial to the turbine efficiency, affects the spatial distribution of the vortex structures shed by the turbine as well as the wake recovery. The results presented in this paper suggest that the velocity recovery in the wake is highly dependent on the very near-wake vortex dynamics. Therefore, we can infer that any geometric parameter affecting the temporal and spatial distributions of the vorticity shed by the blades can significantly alter the wake recovery of vertical-axis turbines.

In this paper, a new system is proposed to improve the thermodynamic and economic indicators of solar room heating. The heat pump is integrated with a conventional solar heating system, in which the temperature of the collected heat is reduced by 20 °C to 30 °C to increase the efficiency of solar energy collection. The low-temperature heat collected by the solar collector is increased using a heat pump to generate high-temperature heat for indoor heating in winter and low-pressure process steam for industrial use in other seasons. The results show that the efficiency of the solar collector has increased by 30.50%, its annual effective operating time has reached 2000 hours, which is about four times more than that of a conventional solar heating system. In addition, the parameters of the solar collector area, the volume of the storage tank and the power of the heat pump have been optimized. This work provides a new way to use solar energy more efficiently and economically. Energy analysis shows that with the new flat solar collectors, the average annual values were 2.5 kW, and also high, the COP system in November was 4%.

Objective: The aim of this study was to determine blood flow volume (BFV) in the normal state and its features in patients with acute posterior circulation ischemic strokes (PCIS) and vertebrobasilar insufficiency (VBI) using color duplex sonography (DS).Methods: The study included DS data from 96 patients with verified PCIS (66 men and 30 women, aged 64±13 years) and 29 adults with VBI (17 men and 12 women, aged 66±11 years). The control group consisted of 65 healthy male volunteers of different ages.Results: In asymptomatic healthy volunteers, there was a significant decrease in BFV in the internal carotid artery (ICA) with age (502 ml/min in young people, 465 ml/min in the older subgroup) with rS = −0.24 ( p = 0.05), and the aggregated BFV in the vertebral arteries (VAs) turned out to be almost constant (141–143 ml/min). In patients with VBI, the aggregated BFV in the VAs (144 ml/min) did not differ from that in healthy volunteers, but the BFV values in the ICAs were significantly lower (325 ml/min). In patients with PCIS, the aggregated BFV in the ICAs was also significantly lower (399 ml/min) than in the control group but did not significantly differ from that in patients with VBI. In patients with PCIS, there was a significant decrease in the aggregated BFV in the VAs (105 ml/min), which distinguished this group from other examined patients.Conclusions: A significant decrease the BFV in the VA was observed only in patients with PCIS and was associated with the presence of steno-occlusive diseases (SOD) more often in the left VA. Patients with VBI had the most pronounced decrease in BFV in the ICA.

This study investigates the role of convection–circulation coupling on the simulated eastward propagation of the Madden–Julian Oscillation (MJO) over the Maritime Continent (MC). Experiments are conducted with the European Centre Hamburg Model Version 5 (ECHAM5) coupled with the one-column ocean model—Snow-Ice-Thermocline (SIT) and two different cumulus schemes, Nordeng-Tiedtke (E5SIT-Nord) and Tiedtke (E5SIT-Tied). During the early phase of MJO composites, the E5SIT-Nord simulation reveals stronger intraseasonal anomalies in the apparent heat source (Q1) over the convective center, however, the E5SIT-Tied produces a stronger background Q1, suggesting that deep convection prevails over the MC but does not couple with the MJO circulation. Similarly, in the E5SIT-Tied simulation, in-column moisture is kept mostly by local deep convection over the MC, which is in contrast to the well-correlated relationship between moisture anomaly and MJO circulation in E5SIT-Nord. A case study based on an observational MJO reveals similar biases concerning of convection–circulation coupling emerges within a few days of simulations. The E5SIT-Tied simulation produces weaker heating at the convective center of the MJO than the E5SIT-Nord a few days after model initiation, resulting weaker subsidence to the east and less favorable for propagation. The present findings highlight the instantaneous responses of cumulus parameterization schemes to MJO-related environmental changes can further affect intraseasonal variability through altering convection–circulation coupling over the MC. Physical schemes of moist convection are essential to realistically represent this coupling and thereby improve the simulation of the eastward propagation of the MJO.

Background Systemic to pulmonary shunt (Shunt) is offered for children with duct dependent pulmonary circulation to augment pulmonary flow. Recently patent ductus arteriosus (PDA) stent (Stent) is widely used as an alternative method. We aimed to compare post intervention outcomes in children underwent either procedure. Methods Infants under 3 months who had an initial palliation by Shunt or Stent were retrospectively reviewed between 2008 and 2016, then followed till the second intervention or 1 year whichever earlier. Results 187 patients (110 Shunt and 77 Stent) were included. Initial weight and pulmonary artery (PA) branches size were similar between the groups. Shunt patients had more shock preoperatively and required more emergency intervention. Stent group showed less ICU stay 4 (1–8) vs 13 (7–23) days, p < 0.0001 and less positive pressure ventilation days 1 (0–2) vs 5.5 (3–11), p < 0.0001. However, Stent group had more symptomatic arterial and deep venous thromboses. In Stent patients the branch PAs growth was better and more homogeneous. At follow-up, no difference between groups regarding cumulative readmission days to hospital, hemoglobin levels and the weight percentile for age. Mortality was not different with a tendency to be higher in the Shunt group (13%) compared to the Stent group (5%), p 0.1. Conclusions The implantation of PDA stent in patients with duct dependent pulmonary circulation results in a smoother ICU course and a shorter hospital stay, with higher risk of vascular injury. Shunt and Stent procedures have a good outcome for PA growth, somatic growth and survival.

In this paper, we consider the desingularization of multiscale solutions to 2D steady incompressible Euler equations. When the background flow ψ 0 is nontrivial, we construct a family of solutions which has nonzero vorticity in small neighborhoods of a given collection of points. One prescribed set of points comprises minimizers of the Kirchhoff-Routh function, while another part of points is on the boundary determined by both ψ 0 and Green's function. Moreover, heights and circulation of solutions have two kinds of scale. We prove the results by considering maximization problem for the vorticity and analyzing the asymptotic behavior of the maximizers.

Looking for an optimal flow shape for culture growth in vortex bioreactors, an intriguing and impressive structure has been observed that mimics the strong swirling flows in the atmosphere (tornado) and ocean (waterspout). To better understand the flow nature and topology, this experimental study explores the development of vortex breakdown (VB) in a lab-scale swirling flow of two immiscible fluids filling a vertical cylindrical container. The rotating bottom disk drives the circulation of both fluids while the sidewall is stationary. The container can be either sealed with the still top disk (SC) or open (OC). As the rotation strength (Re) increases, a new circulation cell occurs in each fluid—the dual VB. In case SC, VB first emerges in the lower fluid at Re = 475 and then in the upper fluid at Re = 746. In case OC, VB first emerges in the upper fluid at Re = 524 and then in the lower fluid at Re = 538. The flow remains steady and axisymmetric with the interface and the free surface being just slightly deformed in the studied range of Re. Such two-VB swirling flows can provide efficient mixing in aerial or two-fluid bioreactors.

In this work, a recent smoothed CFD-DEM model is employed to study the segregation and mixing behaviours in a bi-disperse solid–liquid fluidised bed (SLFB) with different superficial liquid velocities and wide size ratios. Here, the poly-disperse drag model is applied, and its validity and advantage are confirmed. Besides, the qualitative and quantitative characteristics are systematically studied using a variety of indices, while the intermixing behaviour in the transition zone is investigated. The results show that segregation degree is well quantified by the mixing index, and the circulation motion of particles and liquid is confirmed in the transition zone. The more drastic motions can be observed in the transition zone under lower superficial velocities or size ratios. Furthermore, the force analysis in terms of the drag force and collision force indicates that the combined contribution of hydrodynamics and collision is the main underlying mechanism of segregation behaviour in the bi-disperse SLFB.

Bulk nanobubbles (BNBs) have attracted substantial interest from academia and industry owing to their peculiar properties and extensive potential applications. However, a scalable engineering method needs to be developed. Herein, we developed a nanobubble generator based on venturi-type recirculating hydrodynamic cavitation. The existence of nanobubbles produced by our generator was confirmed using physicochemical test methods, including the Tyndall effect, multiple freeze-thaw degassing experiments, and trace metal analysis. Subsequently, the effects of different operating parameters (circulation time and operating pressure) on bulk nanobubble production and properties, as well as their stability, were investigated. The results suggest that the characteristics of BNBs varied with the circulation time (5-20 min) and operating pressure (2-5 bar). However, all the particle size distribution of BNBs had a bimodal distribution with a mean diameter of 180-210 nm for the different circulation time and operating pressures. For example, by increasing the circulation time from 5 to 20 min, the peak value of size distribution decreased from 333/122 nm to 218/52 nm, and the average sample scattering signal count rate (Avg. Count Rate) increased from 133 to 303 Kcps. The evaluation of the stability of the BNBs formed for the circulation time of 15 min and the operating pressure of 3 bar showed that they could continue existence and stability in the suspension for 72 h. The study results might provide a valuable method for further investigation of industrial applications of venturi-type nanobubble generators.

A two-zone model of the atmospheric circulation over a hemisphere is considered. The latitude φ of the boundary between the zone of the Rossby circulation regime at mid and high latitudes and the zone of the Hadley circulation regime at low latitudes serves as a model variable. The principle of maximum of the (information) entropy of the eddy regime within the Rossby regime zone is used to determine a statistical (climatic) equilibrium value of φ. Based on the proposed model, the question of atmospheric blocking action over the hemisphere is addressed. An attempt has been made to represent a blocking phenomenon as a necessary attribute of the atmospheric circulation in statistical equilibrium. The model suggests that long-term climate change related either to the (significant) global warming or to the (significant) global cooling, both respective to the current climate state, and quantified in terms of changes in latitude φ, leads to an increase in the probability of blocking action.

Aim. To study the mechanisms of venous return and the functioning features of lower extremity venous valves in horizontal and vertical positions. Methods. The study, conducted from April 2019 to December 2020, included 100 people. The study participants were divided into 2 groups. The first group was represented by 44 patients (88 limbs) with varicose veins, whose venous system was examined by duplex ultrasound scanning during inpatient rehabilitation. The second (control) group consisted of 56 healthy individuals (92 limbs) without visible signs of venous pathology who underwent an outpatient examination of the venous system. The average age of the patients in the two groups was 49.22.4 and 51.11 years, respectively; women predominated in both groups. The qualitative and quantitative parameters of venous blood flow were studied in the study. Venous valvular insufficiency was assessed by using reflux duration and the Psatakis index. A morphometric study was conducted on 140 limbs of 48 human corpses, from which venous fragments were taken for biomechanical studies of the valves. The clinical characteristics of patients are presented by descriptive statistics, quantitative parameters are reported as the mean value (M) and standard deviation (SD). The differences were tested for significance by using the Student's t-test. Results. In the study, we introduced the concept of the valve index, the aspect ratio of the ellipse, the shape of which has a venous valve in cross-section. Duplex ultrasound scanning, as well as a morphofunctional examination of the valves, made it possible to establish that the valve index is significantly higher in the presence of signs of varicose veins, which indicates dilation and incipient varicose vein, which leads to valvular insufficiency. The elasticity index defined by us, as the indicator of change in the venous lumen size, measured by the ratio of its diameters, also significantly (p=0.034) differed in the studied groups: the elasticity index in the group of healthy people was 1.370.11, in the group of patients with varicose veins 1.560.17. The studied factors allowed us to develop a test that has an important prognostic value for the early diagnosis of varicose veins as well as the implementation of preventive health measures. Conclusion. The features of venous blood circulation and valve function studied in the study not only have prognostic value for the early diagnosis of varicose veins but are also of practical interest for developing methods of surgical correction of venous valvular insufficiency.

Wang et al. [1] publicaram recentemente no Journal of Sports and Heath Science uma revisão intitulada “MicroRNAs in heart and circulation during physical exercise” onde sumarizam o papel regulatório de pequenas moléculas do ácido ribonucleico (RNA) não codificantes, os microRNAs (miRNAs), na fisiopatologia e nas respostas cardiovasculares frente ao exercício físico...

Vacuum preloading is an effective and common method used for clay soil improvement. However, the smear zone generated by the installation of prefabricated vertical drain (PVD) hinders additional efficiency improvements. PVD combined with heat is applied to overcome this problem. This study presents a series of model tests conducted on clayey soil improved by vacuum preloading with different rectangular-wave temperature circulation modes to investigate the effects of cyclic temperature on vacuum consolidation. During the test, the settlement, pore-water pressure, and drainage were monitored. The degree of consolidation was analyzed to evaluate the effectiveness of this method, and the coefficient of energy consumption was used to quantify the energy consumption at different cyclic temperature modes. The results indicated that the rectangular-wave temperature circulation mode of 30–75–30 °C was the most effective. The results of this study contribute substantially to the state of knowledge regarding the cyclic temperature effects on dredged slurry performance subjected to vacuum preloading. Concurrently, a novel approach is introduced for the determination of the optimal soil consolidation.

Fluid transmission lines represent a main element in a wide spectrum of systems and applications such as water supply and circulation networks found in both domestic as well as in industrial facilities. Modeling of fluid transmission lines is therefor a highly important task for analysis, monitoring and control purposes. In this contribution, first principles model representing the propagation and interaction of the fluid’s temperature is presented. Using this general mathematical representation, two simulation models are realized based on different simplifying assumptions, i.e. pure convective flow, effective convective diffusive flow. The two simulation models are then used to describe an exemplary circulation network present at the head quarters of the company VIEGA. The experimental setup as well as two measured data sets used for parameter identification and validation of the two model instances are presented. Finally both model instances are compared against the experimental data outlining the advantages and disadvantages of each model. For the case of non zero flow both models showed high accuracy in the prediction of the water temperature distribution with mean percentage error (MPE) below 4%. For the cases with time periods of zero flow, the first model failed to maintain the high prediction accuracy, where the prediction’s MPE showed significantly higher values up to 10%. However, the second model showed robustness regarding flow stagnation preserving the high prediction accuracy with MPE below 3% and maximum absolute error below 5 [ ° C ] . The computational burden of the models is analyzed for the simulations performed. The models feasibility for real-time applications can be claimed as the models showed an average step computation time below 20 [ms] for a highly optimized C-code implementation on a development computer.

Due to its large northward heat transport, the Atlantic meridional overturning circulation influences both weather and climate at the mid-latitude Northern Hemisphere. Here we use a state-of-the-art global weather/climate modeling system with high resolution (GFDL CM4C192) to quantify this influence focusing on the U.S. extreme cold weather during winter. We perform a control simulation and the water-hosing experiment to obtain two climate states with and without a vigorous Atlantic meridional overturning circulation. We find that in the control simulation with an overturning circulation, the U.S. east of the Rockies is a region characterized by intense north-south heat exchange in the atmosphere during winter. Without the northward heat transport by the overturning circulation in the hosing experiment, this channel of atmospheric heat exchange becomes even more active through the Bjerknes compensation mechanism. Over the U.S., extreme cold weather intensifies disproportionately compared with the mean climate response after the shutdown of the overturning circulation. Our results suggest that an active overturning circulation in the present-day climate likely makes the U.S. winter less harsh and extreme. A shutdown of the Atlantic Meridional Overturning Circulation could lead to a disproportionate increase in the occurrence of extremely cold weather in the U.S. via enhanced north-south heat exchange in the atmosphere, suggest simulations with and without a vigorous overturning circulation.

The article is devoted to the circulation of restricted information. The problems related to the circulation of restricted information in Ukraine are studied, and the international experience in the field of information resources protection is analyzed.

Настоящая публикация является второй частью исследования, посвященного проблеме заимствования Первого собрания сочинений известного аскетического писателя Церкви Востока Исаака, епископа Ниневийского, христианами других конфессий. В данной части представлены результаты текстологического анализа разночтений имён авторитетных духовных писателей, цитируемых св. Исааком. Анализ был осуществлен по доступным автору сирийским манускриптам восточносирийского, западносирийского и сиро-халкидонского происхождения, которые в изначальном виде содержали полный текст Первого собрания св. Исаака Сирина, а также по греческому переводу и нескольким арабским рукописям. Задача исследования - восстановить историю филиации текста Первого собрания при пересечении конфессиональных границ. По результатам исследования удалось зафиксировать модификации текста во всех случаях употребления св. Исааком имён авторитетных для восточносирийской церковной традиции авторов: Диодора Тарсийского, Феодора Мопсуестийского и Евагрия Понтийского. При пересечении конфессиональных границ эти имена или относящиеся к ним эпитеты были заменены или пропущены с целью очищения исходного текста от нежелательных для переписчиков других конфессий элементов. При этом аутентичное чтение всегда засвидетельствовано списками восточносирийской редакции. В заключение автор исследования предлагает новую классификацию сирийских манускриптов, разделив их на четыре группы в зависимости от их происхождения и содержащихся в них чтений имён. В процессе исследования была установлена неизвестная доселе церковно-конфессиональная принадлежность нескольких манускриптов. Впервые удалось прояснить причины ряда текстуальных разночтений в восточносирийских списках, подвергшихся интерполяции со стороны сиро-ортодоксальных читателей. Isaac, bishop of Nineveh, belongs to the Church of the East’s most famous ascetic authors This three-part study explores the way how the First Part of his writings was adopted in other Syriac Christian communities. The second part analyzes variant readings of personal names of some important church figures in Isaac of Nineveh’s writings. Makarov uses all available Syriac manuscripts of East Syriac, West Syriac, and Chalcedonian Syriac origin, which initially contained the full text of the First Part, as well as its Greek and Arabic manuscripsts. Makarov seeks to reconstruct how the text changed as it crossed borders of different Christian communities. For that purpose, he explores variant readings of names of persons considered important in the Eastern Syriac tradition: Diodorus of Tarsus, Theodore of Mopsuestia, and Evagrius Ponticus. When Isaac’s writings were adopted in other Syriac Christian communities, the names or titles of those persons were intentionally removed or altered in order to purge the original text from the elements viewed as heterodox by the copyists and translators. In the East Syriac texts, however, the original reading is always preserved. Makarov proposes a new classification of the Syriac manuscripts based on their origin and on forms of personal names they contain. He also clarifies the origin of some previously unattributed manuscripts and explains variation in the East Syriac manuscripts, which, as he argued, is due to the later Jacobite readers.

This study investigates the stratosphere-troposphere coupling associated with the Scandinavian (SCA) pattern in boreal winter. The results indicate that the SCA impacts stratospheric circulation but that its positive and negative phases have different effects. The positive phase of the SCA (SCA+) pattern is restricted to the troposphere, but the negative phase (SCA−) extends to the upper stratosphere. The asymmetry between phases is also visible in the lead-lag evolution of the stratosphere and troposphere. Prominent stratospheric anomalies are found to be intensified following SCA+ events, but prior to SCA− events. Further analysis reveals that the responses are associated with upward propagation of planetary waves, especially wavenumber 1 which is asymmetric between SCA phases. The wave amplitudes in the stratosphere, originating from the troposphere, are enhanced after the SCA+ events and before the SCA− events. Furthermore, the anomalous planetary wave activity can be understood through its interference with climatological stationary waves. Constructive wave interference is accompanied by clear upward propagation in the SCA+ events, while destructive interference suppresses stratospheric waves in the SCA− events. Our results also reveal that the SCA+ events are more likely to be followed by sudden stratospheric warming (SSW) events, because of the deceleration of stratospheric westerlies following the SCA+ events.

Reliable simulations of historical and future climate are critical to assessing ecological and hydrological responses over the Third Pole (TP). In this study, we evaluate the historical and future temperature and precipitation simulations of 18 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) in southeastern TP (SETP) and the upstream of the Amu Darya and Syr Darya (UAS) regions, two typical TP subregions dominated by the Indian summer monsoon system and westerlies, respectively. Comparison against station observations suggests that CMIP6 models generally capture the intra-annual variability and spatial pattern of historical climate over both subregions. However, the wetting and cold biases observed in CMIP5 still persist in CMIP6; annual temperature is underestimated by most models and annual precipitation is overestimated by all models. Multi-model average cold biases in SETP and UAS are 1.18°C and 0.32°C, respectively, and wet biases in SETP and UAS are 119% and 46%, respectively. We further analyze climate projections under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. Both SETP and UAS subregions are projected to experience significant warming in 2015–2100, with warming trends 34%–42% and 40%–50% higher than the global trend, respectively. Model projections suggest that the warming trend will slow down under SSP1-2.6 and SSP2-4.5 but further intensify under SSP5-8.5 in 2050–2100. Monsoon-dominated SETP is projected to experience a significant wetting trend stronger than UAS over the entire future period, especially in summer (cf. winter in westerlies-dominated UAS). Concurrently, a significant drying trend in summer is found in UAS during 2050–2100 under SSP5-8.5, suggesting the intensified uneven distributions of seasonal precipitation based on projections.

PURPOSE Three-dimensional (3D) quantification of circulation using a Finite Elements methodology. METHODS We validate our 3D method using an in-silico arch model, for different mesh resolutions, image resolution and noise levels, and we compared this with a currently used 2D method. Finally, we evaluated the application of our methodology in 4D Flow MRI data of ascending aorta of six healthy volunteers, and six bicuspid aortic valve (BAV) patients, three with right and three with left handed flow, at peak systole. The in-vivo data was compared using a Mann-Whitney U-test between volunteers and patients (right and left handed flow). RESULTS The robustness of our method throughout different image resolutions and noise levels showed subestimation of circulation less than 45 cm2 /s in comparison with the 55cm2 /s generated by the current 2D method. The circulation (mean ± SD) of the healthy volunteer group was 13.83 ± 28.78 cm2 /s, in BAV patients with right-handed flow 724.37 ± 317.53 cm2 /s, and BAV patients with left-handed flow -480.99 ± 387.29 cm2 /s. There were significant differences between healthy volunteers and BAV patients groups (P-value < .01), and also between BAV patients with a right-handed or left-handed helical flow and healthy volunteers (P-value < .01). CONCLUSION We propose a novel 3D formulation to estimate the circulation in the thoracic aorta, which can be used to assess the differences between normal and diseased hemodynamic from 4D-Flow MRI data. This method also can correctly differentiate between the visually seen right- and left-handed helical flow, which suggests that this approach may have high clinical sensitivity, but requires confirmation in longitudinal studies with a large cohort.

OPEN/CLOSED: ROOMS/CORRIDORS rethinks the conventional tradeshow experience by reimagining and reconfiguring walls, openings, and paths to produce a series of corridor-ish rooms and room-ish corridors.

The main objective of this study is to verify different (semi)empirical formulas used to predict hydrodynamic parameters of a fluidized bed against CFD simulations. The hydrodynamic parameters investigated include minimum fluidization velocity, bed voidage at minimum fluidization condition, bubble diameter, and bubble velocity. All simulations were completed using a 3D Euler-Euler-based model available in ANSYS Fluent 19.2. The study of solid volume-averaged velocity inside the bed revealed a minimum fluidization velocity of 0.194 m/s, which was in agreement with the result obtained when the pressure drop in a fluidized bed was set equal to that in a fixed bed. The time-averaged solid volume fraction showed that the constant value of 0.476 (with the assumption of the uniform cubic mode of packing) was a good estimation for bed voidage at minimum fluidization condition. The study of air turbulent viscosity demonstrated high air turbulence above the bed and inside large bubbles within the bed. Higher mean bed heights and higher levels of air circulation were observed at higher air flowrates. The analysis of different formulas predicting bubble diameter and bubble velocity at different bed heights and air flowrates showed that Yasui-Johnson's formula for estimating the bubble diameter could produce results in good agreement with our CFD simulations for the tested geometry and initial conditions.

Seismocardiography measures the vibrations produced by the beating heart using an accelerometer sensor placed on the chest. We evaluated the ability of smartphone seismocardiography to distinguish between the presence and absence of spontaneous circulation.Seismocardiography signals were obtained using a smartphone placed on the sternum in a convenience sample of 60 adult patients (30 comatose patients with spontaneous circulation and 30 deceased patients). The maximum, minimum, and standard deviation (SD) of acceleration values for head-to-foot, right-to-left, and dorsoventral axes and the three axis-root mean square (RMS) of the acceleration signals were calculated. Blinded observers (n = 156) were each asked to determine the presence or absence of spontaneous circulation based on seismocardiography video clips for each of the 60 patients.The seismocardiography revealed periodic large positive peaks in the patients with spontaneous circulation, which were absent in the patients without spontaneous circulation. For each of the four output measurements (three independent axes plus the three-axis RMS), the acceleration maxima and SD were significantly higher and the minima significantly lower in the patients with spontaneous circulation than in those without spontaneous circulation (all P 0.001 except the minimum of three axis-RMS results [P = 0.009]). The observers accurately identified the seismocardiography signals from patients without spontaneous circulation, with a sensitivity of 97.6% (95% confidence interval, 97.0%-98.2%) and a specificity of 98.4% (95% confidence interval, 97.8%-99.0%).In conclusion, blinded observers accurately distinguished between seismocardiography signals from patients with and without spontaneous circulation.

In terms of the importance of reducing the influences of curvature induced circulation secondary flow, several counteracting techniques/measures have been studied. Although the previous techniques have obtained good results yet, they involve fixed and permanent construction works in the channel. Most of the techniques have a negative impact on navigation, and may be damaged under extreme flow conditions. Therefore, the use of new technique has become very significant and must be studied. The aim of this paper to study a new technique as an indirect tool to counteract the impact of the secondary flow on the banks and bed at channel bends by re-distribution of the main flow velocity in the curved section through water jets. In a previous experiment, air bubbles are induced as a bubble screen (air media) with an appropriate velocity, through a porous tube placed near the outer bank in the sharply open channel bend 193°. In this paper, one of the previous experiments is modeled with the same shape and conditions, however, the induced air bubbles from the porous tube in the experiment are replaced by a water screen to act as a source of momentum. A numerical model FLUENT was implemented and a realizable K-e turbulent model was used to scrutinize and predict the velocity pattern in the channel bend. The impact of the change in lateral water jets flow from the porous tube was also investigated and results presented and compared. The results revealed that the water screen technique contributes in reducing the downward movement of the secondary circulation, dragging the flow upward, leading to the distribution of the secondary circulation, and shifting the core of maximum downstream velocities away from the outer bank towards the inner bank at the junction of generated circulation. The results also showed that the water screen is able to counteract the effect of the main flow circulation cells provided that this secondary flow is not less than 20% of the main flow and the corresponding velocity is also not less than 40% of the main flow velocity.

The paper presents a computational analysis of regularities in the accumulation of slags during the interaction of lead and lead-bismuth coolants with oxygen gas. Oxidation of lead-containing coolants will cause the formation of lead oxide, while the formation of bismuth oxide is unlikely. Dosed supply of oxidizing gas to lead-containing coolants makes it possible to oxidize, selectively, chromium and nickel to their oxides without the slag formation from solid lead oxide. Regularities were studied which are involved in the lead oxide formation during the interaction of lead-containing coolants with oxygen gas. It has been found that, in the process of interacting with oxygen gas, a lead-bismuth alloy is oxidized 1.7 times as intensively as lead, this being explained by the presence of bismuth in the alloy. Bismuth is oxidized more intensively than both lead and the lead-bismuth alloy. The inert gas overpressure during depressurization does not prevent air oxygen from entering the circuit, and the dependence of the nitrogen and oxygen flow into the circuit on the argon flow out of the loop is close to linear regardless of the circuit state (cold, without coolant; heated, without coolant; heated, with circulating coolant). Oxygen is a chemically active impurity and is absorbed by the circuit; it is therefore important to control nitrogen in the gas spaces of the reactor and research plant circuits with lead-containing coolants. This will make it possible to signal, in a timely manner, the ingress of oxygen into the circuit and to take measures required to avoid or reduce the scale of the slag formation from lead oxides.

This study used model experiments to investigates hydraulic characteristics of flow at marguerite-shaped inlets with holes at the bottom of their lobes, known as modern marguerite-shaped inlets. This innovation reduces the swirling flow strength and improves the hydraulic performance of simple shaft spillways. Head–discharge relationships, flow circulation, threshold and critical submergence depths, and discharge coefficients are detailed for different flow regimes. The findings suggest that flow discharges through this type of inlet were approximately six, three, and two times greater than flow discharges through a simple shaft spillway, a circular piano key inlet, and a simple marguerite-shaped inlet, respectively. Increasing the outer length and height of inlets also uniformly distributed the flow around shaft spillways. The best hydraulic performance was observed in the inlets with an outer height of 1.25D and an outer length of 3.75D, where D is the diameter of the shaft spillway. Different equations, with high correlations and low errors, were derived to determine the threshold and critical submergence depths and the discharge coefficients for free and orifice flow regimes.

In this paper, an experiment of a robotic model at Reynolds number of approximately 240 is performed with the aim of establishing a scaling law for describing the circulation growth of the leading-edge vortex (LEV) on a flapping wing. Three typical modes of wing rotation, i.e., advanced, symmetric, and delayed modes, are considered to examine the effects of wing rotation on the scaling formation of LEV. The streamwise velocity fields of the LEV along the span of the wing are measured by particle image velocimetry technique. Experimental results demonstrated that a spirally three dimensional (3D) LEV with spanwise distribution of circulation rolls up on the upper surface of wing and the circulation of LEV usually obtains the peak before the end of wing stroke. Based on the concept of vortex formation time, the formation time of the 3D LEV are defined in two distinct manners. One (denoted by $$T_{\text {LEV}}^*$$ ) is defined based on the LEV circulation, and the other (denoted by $$T_{\text {LEV}}^{**}$$ ) is defined based on the wing kinematics. It is found that $$T_{\text {LEV}}^{**}$$ increases monotonously during the upstroke and downstroke, whereas $$T_{\text {LEV}}^*$$ generally arrives peaks and then decreases. The peak value of $$T_{\text {LEV}}^*$$ indicates the formation number of LEV, which stays in the range of 2.5–5.5, agrees with the scaling formation number predicted by other vortices. Moreover, the mode of wing rotation plays a controllable role in the formation number of LEV by modulating the characteristic length scale that feeds the formation of LEV. After reaching the formation number, the LEVs stably remain attached on the flapping wing and even further grow at some spanwise locations because of vorticity transport. Furthermore, the linear relationship between $$T_{\text {LEV}}^*$$ and $$T_{\text {LEV}}^{**}$$ before reaching the formation number can suggest a potential model for predicting the circulation growth of LEV based on wing kinematics.

This paper examines the potential of reconstructing the Atlantic Meridional Overturning Circulation (AMOC) using surface data and linear machine learning algorithms. The algorithms are trained on p...

Microphysical processes are important for the development of clouds and thus Earth's climate. For example, turbulent fluctuations in the water vapor mixing ratio, r, and temperature, T, cause fluctuations in the saturation ratio, S. Because S is the driving factor in the condensational growth of droplets, fluctuations may broaden the cloud droplet size distribution due to individual droplets experiencing different growth rates. The small-scale turbulent fluctuations in the atmosphere that are relevant to cloud droplets are difficult to quantify through field measurements. We investigate these processes in the laboratory using Michigan Tech's Π Chamber. The Π Chamber utilizes Rayleigh–Bénard convection (RBC) to create the turbulent conditions inherent in clouds. In RBC it is common for a large-scale circulation (LSC) to form. As a consequence of the LSC, the temperature field of the chamber is not spatially uniform. In this paper, we characterize the LSC in the Π Chamber and show how it affects the shape of the distributions of r, T, and S. The LSC was found to follow a single roll with an updraft and downdraft along opposing walls of the chamber. Near the updraft (downdraft), the distributions of T and r were positively (negatively) skewed. At each measuring position, S consistently had a negatively skewed distribution, with the downdraft being the most negative.

The goal was to present an approach where the micro-scale events related to single-particle motion directly translate onto higher levels and produce large-scale observable phenomena related to transport and mixing. Three multiphase hydrodynamic effects were considered, analysed and discussed: added mass, drift, wake. Although the results are of general validity, the spherical-cap shape (cap bubble) was used as the definite object for demonstration. It was shown how the unsteady inertial effect of added mass (coefficient C), irrelevant for mixing, is related to the steady kinematic concept of Darwin drift (coefficient D) that is directly associated with mixing. It was shown how the inviscid drift and the viscous wake operate and contribute to the resulting circulation and mixing. List of currently available formulas for C was completed, which are usable for estimation of D.

Animals swim in water, fly in air, or dive into water to find mates, chase prey, or escape from predators. Even though these locomotion modes are phenomenologically distinct, we can rationalize the underlying hydrodynamic forces using a unified fluid potential model. First, we review the previously known complex potential of a moving thin plate to describe circulation and pressure around the body. Then, the impact force in diving or thrust force in swimming and flying are evaluated from the potential flow model. For the impact force, we show that the slamming or impact force of various ellipsoid-shaped bodies of animals increases with animal weight, however, the impact pressure does not vary much. For fliers, birds and bats follow a linear correlation between thrust lift force and animal weight. For swimming animals, we present a scaling of swimming speed as a balance of thrust force with drag, which is verified with biological data. Under this framework, three distinct animal behaviors (i.e., swimming, flying, and diving) are similar in that a thin appendage displaces and pressurizes a fluid, but different in regards to the surroundings, being either fully immersed in a fluid or at a fluid interface.