Fluids Pub Date : 2023-10-27 DOI: 10.3390/fluids8110287

Somaris E. Quintana, Maria Zuñiga-Navarro, David Ramirez-Brewer, Luis A. García-Zapateiro

引用次数: 0

Investigations into the Effect of Mixing on Steam–Water Two-Phase Subsonic Cross-Flow Stability 混合对蒸汽-水两相亚音速横流稳定性影响的研究

Fluids Pub Date : 2023-10-27 DOI: 10.3390/fluids8110286

Hassan Ali Ghazwani, Khairuddin Sanaullah, Vladimir Vladimirovich Sinitsin, Afrasyab Khan

{"title":"Investigations into the Effect of Mixing on Steam–Water Two-Phase Subsonic Cross-Flow Stability","authors":"Hassan Ali Ghazwani, Khairuddin Sanaullah, Vladimir Vladimirovich Sinitsin, Afrasyab Khan","doi":"10.3390/fluids8110286","DOIUrl":"https://doi.org/10.3390/fluids8110286","url":null,"abstract":"Theoretical and experimental aspects of the project were conducted to investigate the effect of the mixing of a swirling steam jet into cross-flowing water. It was observed that based on the theoretical adiabatic estimations for the equilibrium temperature of steam–water mixing and by varying Psteam = 1–3 bar, Pwater = 1 bar and RPM = 60–300 around 97% (experimentally compared to the area it has at initial condition) and 85% (CFD study compared to the area it has at initial condition), an increase in the area under the influence of perfect adiabatic mixing was found. A virtual cover over the steam duct was seen. The area of this virtual cover based on the void fraction of swirling steam had a weak relationship with the total area of the region, inhibiting the perfect mixing for which an analytical relationship had been developed. The effect of mixing on the stability of swirling steam–water cross-flows was overall more than twice that of the effect on the area under the influence of the stability profile protrusions. Thus, an overall rise in inlet pressure contributed to improper mixing, whereas a rise in the RPM contributed to proper mixing inside a fixed window of observations. The effect of spatial scaling of a swirling steam trajectory on mixing in cross-flowing water was also investigated across the vertical plane. Also, the scaling of the vertical trajectories of the swirling steam jets under all operating conditions resulted in merging the regions of perfect mixing to some extent. Thus, the area under the influence of perfect mixing was reduced to around 3–4.7% under all operating conditions with scaling. This type of scaling has enormous potential for the characterization of larger fluid domains in environmental and process engineering studies.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"12 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Differential Rotation in Convecting Spherical Shells with Non-Uniform Viscosity and Entropy Diffusivity 具有非均匀粘性和熵扩散率的对流球壳的微分旋转

Fluids Pub Date : 2023-10-27 DOI: 10.3390/fluids8110288

Parag Gupta, David MacTaggart, Radostin D. Simitev

{"title":"Differential Rotation in Convecting Spherical Shells with Non-Uniform Viscosity and Entropy Diffusivity","authors":"Parag Gupta, David MacTaggart, Radostin D. Simitev","doi":"10.3390/fluids8110288","DOIUrl":"https://doi.org/10.3390/fluids8110288","url":null,"abstract":"Contemporary three-dimensional physics-based simulations of the solar convection zone disagree with observations. They feature differential rotation substantially different from the true rotation inferred by solar helioseismology and exhibit a conveyor belt of convective “Busse” columns not found in observations. To help unravel this so-called “convection conundrum”, we use a three-dimensional pseudospectral simulation code to investigate how radially non-uniform viscosity and entropy diffusivity affect differential rotation and convective flow patterns in density-stratified rotating spherical fluid shells. We find that radial non-uniformity in fluid properties enhances polar convection, which, in turn, induces non-negligible lateral entropy gradients that lead to large deviations from differential rotation geostrophy due to thermal wind balance. We report simulations wherein this mechanism maintains differential rotation patterns very similar to the true solar profile outside the tangent cylinder, although discrepancies remain at high latitudes. This is significant because differential rotation plays a key role in sustaining solar-like cyclic dipolar dynamos.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"57 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136318319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Reducing Aerodynamic Drag on Flatbed Trailers for Passenger Vehicles Using Novel Appendable Devices 利用新型可附加装置减小乘用车平板挂车的气动阻力

Fluids Pub Date : 2023-10-27 DOI: 10.3390/fluids8110289

Michael Gerard Connolly, Malachy J. O’Rourke, Alojz Ivankovic

{"title":"Reducing Aerodynamic Drag on Flatbed Trailers for Passenger Vehicles Using Novel Appendable Devices","authors":"Michael Gerard Connolly, Malachy J. O’Rourke, Alojz Ivankovic","doi":"10.3390/fluids8110289","DOIUrl":"https://doi.org/10.3390/fluids8110289","url":null,"abstract":"This article presents a study on the aerodynamic drag of a generic dual-axle flatbed trailer and explores ways to reduce the drag using appendable drag-reducing devices. The primary sources of drag originated from the van and trailer’s rear, along with the trailer’s wheels. The most-effective initial device for reducing drag was a full trailer underside cover, which offered a 7% drag reduction. Additionally, ladder racks, dropsides, and rear gates were studied, and it was found that protruding ladder racks significantly increased drag. Rear gates added large amounts of drag and should be removed and stored when not needed. The study also explored novel mid-section devices that increased the van’s base pressure and reduced drag. An axle test revealed that drag for single-, dual-, and triple-axle trailers was very similar in direct flow, but different in yawed flow. A drawbar length test showed a near-linear relationship between drawbar length and drag, manifesting as a 1.7% change in drag per 250 mm change in drawbar length. Several novel modifications were made to the trailer, including fitting six unique appendable devices, which offered a total 7.3% drag reduction. A novel rear van device known as the multi-stage converging cavity was introduced, which reduced drag by nearly 18%. When all the devices were used together, a total 25% drag reduction was observed for the van–trailer combination.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136318136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An Enhanced Python-Based Open-Source Particle Image Velocimetry Software for Use with Central Processing Units 一个增强的基于python的开源粒子图像测速软件，用于中央处理单元

Fluids Pub Date : 2023-10-27 DOI: 10.3390/fluids8110285

Ali Shirinzad, Khodr Jaber, Kecheng Xu, Pierre E. Sullivan

引用次数: 0

Rendering Maxwell Equations into the Compressible Inviscid Fluid Dynamics Form 将麦克斯韦方程组转换为可压缩无粘流体动力学形式

Fluids Pub Date : 2023-10-26 DOI: 10.3390/fluids8110284

Peter Vadasz

引用次数: 0

Settling Flow Details in the Flash Smelting Furnace—A CFD-DEM Simulation Study 闪速熔炼炉沉降流程细节CFD-DEM模拟研究

Fluids Pub Date : 2023-10-23 DOI: 10.3390/fluids8100283

Jani-Petteri Jylhä, Ari Jokilaakso

{"title":"Settling Flow Details in the Flash Smelting Furnace—A CFD-DEM Simulation Study","authors":"Jani-Petteri Jylhä, Ari Jokilaakso","doi":"10.3390/fluids8100283","DOIUrl":"https://doi.org/10.3390/fluids8100283","url":null,"abstract":"The flash smelting furnace has previously been simulated using computational fluid dynamics (CFD). A new approach is to combine CFD and the discrete element method (DEM) for more detailed simulations of the different phenomena that occur as copper matte droplets settle through a slag layer. One of the most important phenomena found is the formation of a channeling flow which carries matte droplets faster through the slag. However, such phenomena cannot be directly observed in the flash smelting furnace settler due to the extreme temperatures of the opaque molten slag inside the furnace, therefore alternative methods are required for validating the phenomenon. In this work, the simulated channeling flow is validated with a sphere–oil model. The phenomenon was similar in all of the studied cases, although in the experimental setup the spheres settled faster in the oil model than in the simulations. The differences were most likely caused by the cohesion of the spheres and slight differences in the properties provided by the manufacturer and real properties for the oil and the spheres, and by the fact that simulation ignores surface tension and changing air–oil and water–oil interfaces.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"338 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135366752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Detailed Numerical Study on Aerodynamic Interactions of Tandem Wheels on a Generic Vehicle 通用车辆串联车轮气动相互作用的详细数值研究

Fluids Pub Date : 2023-10-20 DOI: 10.3390/fluids8100281

Radoje Radovic, Fatemeh Salehi, Sammy Diasinos

{"title":"A Detailed Numerical Study on Aerodynamic Interactions of Tandem Wheels on a Generic Vehicle","authors":"Radoje Radovic, Fatemeh Salehi, Sammy Diasinos","doi":"10.3390/fluids8100281","DOIUrl":"https://doi.org/10.3390/fluids8100281","url":null,"abstract":"Wheels contribute significantly to the aerodynamic performance of ground vehicles. Many studies have focused on investigating a single wheel either in isolation or in a wheelhouse. However, there has been less focus on the flow field around a rear wheel, especially when considering varying proximity to the front wheel, despite its importance on aerodynamic forces. In this study, a generic reference body is modified and fitted with a rear wheel within a wheelhouse and analysed while the wheel spacing varies. Reynolds-Averaged Navier–Stokes (RANS) modelling was employed to allow for multiple variations to be considered and the model produced results in good agreement with experimental results. The results confirm that two upper rear wheelhouse outflow vortices are only present when the wheel spacing is short. It was found that the drag values were minimal for the wheel spacing at a critical distance of 1.5 wheel diameters. At this wheel spacing, the formation of the outboard jetting vortex is prevented at the rear wheel, and hence, the rear wheel drag is reduced by more than 10%. Any further reduction in the spacing does not provide any drag benefits. Also, the outflow from the front wheelhouse is projected further away from the body, drawing flow from the rear wheelhouse into the outboard jetting vortex.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Comparison of Newtonian and Non-Newtonian Models for Simulating Stenosis Development at the Bifurcation of the Carotid Artery 模拟颈动脉分叉处狭窄发展的牛顿和非牛顿模型的比较

Fluids Pub Date : 2023-10-20 DOI: 10.3390/fluids8100282

Aikaterini C. Stamou, Jovana Radulovic, James M. Buick

引用次数: 0

Numerical Simulation of Taylor—Couette—Poiseuille Flow at Re = 10,000 Re = 10,000时Taylor-Couette-Poiseuille流动的数值模拟

Fluids Pub Date : 2023-10-19 DOI: 10.3390/fluids8100280

Andrey Gavrilov, Yaroslav Ignatenko

引用次数: 0

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