Alex G. Kuchumov, Anastasiya Makashova, Sergey Vladimirov, Vsevolod Borodin, Anna Dokuchaeva
The complicated interaction between a fluid flow and a deformable structure is referred to as fluid–structure interaction (FSI). FSI plays a crucial role in the functioning of the aortic valve. Blood exerts stresses on the leaflets as it passes through the opening or shutting valve, causing them to distort and vibrate. The pressure, velocity, and turbulence of the fluid flow have an impact on these deformations and vibrations. Designing artificial valves, diagnosing and predicting valve failure, and improving surgical and interventional treatments all require the understanding and modeling of FSI in aortic valve dynamics. The most popular techniques for simulating and analyzing FSI in aortic valves are computational fluid dynamics (CFD) and finite element analysis (FEA). By studying the relationship between fluid flow and valve deformations, researchers and doctors can gain knowledge about the functioning of valves and possible pathological diseases. Overall, FSI is a complicated phenomenon that has a great impact on how well the aortic valve works. Aortic valve diseases and disorders can be better identified, treated, and managed by comprehending and mimicking this relationship. This article provides a literature review that compiles valve reconstruction methods from 1952 to the present, as well as FSI modeling techniques that can help advance valve reconstruction. The Scopus, PubMed, and ScienceDirect databases were used in the literature search and were structured into several categories. By utilizing FSI modeling, surgeons, researchers, and engineers can predict the behavior of the aortic valve before, during, and after surgery. This predictive capability can contribute to improved surgical planning, as it provides valuable insights into hemodynamic parameters such as blood flow patterns, pressure distributions, and stress analysis. Additionally, FSI modeling can aid in the evaluation of different treatment options and surgical techniques, allowing for the assessment of potential complications and the optimization of surgical outcomes. It can also provide valuable information on the long-term durability and functionality of prosthetic valves. In summary, fluid–structure interaction modeling is an effective tool for predicting the outcomes of aortic valve surgery. It can provide valuable insights into hemodynamic parameters and aid in surgical planning, treatment evaluation, and the optimization of surgical outcomes.
{"title":"Fluid–Structure Interaction Aortic Valve Surgery Simulation: A Review","authors":"Alex G. Kuchumov, Anastasiya Makashova, Sergey Vladimirov, Vsevolod Borodin, Anna Dokuchaeva","doi":"10.3390/fluids8110295","DOIUrl":"https://doi.org/10.3390/fluids8110295","url":null,"abstract":"The complicated interaction between a fluid flow and a deformable structure is referred to as fluid–structure interaction (FSI). FSI plays a crucial role in the functioning of the aortic valve. Blood exerts stresses on the leaflets as it passes through the opening or shutting valve, causing them to distort and vibrate. The pressure, velocity, and turbulence of the fluid flow have an impact on these deformations and vibrations. Designing artificial valves, diagnosing and predicting valve failure, and improving surgical and interventional treatments all require the understanding and modeling of FSI in aortic valve dynamics. The most popular techniques for simulating and analyzing FSI in aortic valves are computational fluid dynamics (CFD) and finite element analysis (FEA). By studying the relationship between fluid flow and valve deformations, researchers and doctors can gain knowledge about the functioning of valves and possible pathological diseases. Overall, FSI is a complicated phenomenon that has a great impact on how well the aortic valve works. Aortic valve diseases and disorders can be better identified, treated, and managed by comprehending and mimicking this relationship. This article provides a literature review that compiles valve reconstruction methods from 1952 to the present, as well as FSI modeling techniques that can help advance valve reconstruction. The Scopus, PubMed, and ScienceDirect databases were used in the literature search and were structured into several categories. By utilizing FSI modeling, surgeons, researchers, and engineers can predict the behavior of the aortic valve before, during, and after surgery. This predictive capability can contribute to improved surgical planning, as it provides valuable insights into hemodynamic parameters such as blood flow patterns, pressure distributions, and stress analysis. Additionally, FSI modeling can aid in the evaluation of different treatment options and surgical techniques, allowing for the assessment of potential complications and the optimization of surgical outcomes. It can also provide valuable information on the long-term durability and functionality of prosthetic valves. In summary, fluid–structure interaction modeling is an effective tool for predicting the outcomes of aortic valve surgery. It can provide valuable insights into hemodynamic parameters and aid in surgical planning, treatment evaluation, and the optimization of surgical outcomes.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"42 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135774629","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}
Mok-Lyang Cho, Hyeon-Ji Choi, Seo-Jin Kim, Ji-Soo Ha
In this study, we analyze the performance of ventilation modules to improve air quality in educational facilities. Using (CFD), we examine the flow design variables of a window-mounted ventilation module. Using computational analysis, we analyze various flow design characteristics of window-mounted ventilation modules and review optimal conditions. First, we measure the carbon dioxide concentration in the classroom and use CFD to analyze the internal air characteristics according to the ventilation module’s inflow speed, inflow angle, and indoor temperature conditions. According to classroom air quality management standards, the concentration of carbon dioxide must be managed below 1000 ppm. When the ventilation module’s inflow velocity was 2.0 m/s, a carbon dioxide concentration of less than 1000 ppm was measured in the classroom. Additionally, an air filter was selected to prevent the inflow of external fine dust through the ventilation module. The suitability of HEPA H14 was reviewed to design the weight concentration of fine dust flowing from the ventilation module to be less than 50 μg/m3. Through research, flow design conditions for a window-mounted ventilation module were presented to reduce carbon dioxide concentration inside the classroom. The analysis of the ventilation system flow characteristics proposed in this study derived primary data for improving the classroom ventilation system.
{"title":"Analysis of Flow Characteristics of Window-Combination-Type Ventilation System Using CFD","authors":"Mok-Lyang Cho, Hyeon-Ji Choi, Seo-Jin Kim, Ji-Soo Ha","doi":"10.3390/fluids8110294","DOIUrl":"https://doi.org/10.3390/fluids8110294","url":null,"abstract":"In this study, we analyze the performance of ventilation modules to improve air quality in educational facilities. Using (CFD), we examine the flow design variables of a window-mounted ventilation module. Using computational analysis, we analyze various flow design characteristics of window-mounted ventilation modules and review optimal conditions. First, we measure the carbon dioxide concentration in the classroom and use CFD to analyze the internal air characteristics according to the ventilation module’s inflow speed, inflow angle, and indoor temperature conditions. According to classroom air quality management standards, the concentration of carbon dioxide must be managed below 1000 ppm. When the ventilation module’s inflow velocity was 2.0 m/s, a carbon dioxide concentration of less than 1000 ppm was measured in the classroom. Additionally, an air filter was selected to prevent the inflow of external fine dust through the ventilation module. The suitability of HEPA H14 was reviewed to design the weight concentration of fine dust flowing from the ventilation module to be less than 50 μg/m3. Through research, flow design conditions for a window-mounted ventilation module were presented to reduce carbon dioxide concentration inside the classroom. The analysis of the ventilation system flow characteristics proposed in this study derived primary data for improving the classroom ventilation system.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135933787","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}
The report presents the approach implemented in the Russian LOGOS software package for the numerical simulation of the marine propeller flow problems using unstructured computational meshes automatically generated by the mesh generator. This approach includes a computational model based on the Navier–Stokes equation system and written with respect to the physical process: the turbulent nature of flow with transient points is accounted using the Reynolds Averaged Navier–Stokes method and the k–ω SST model of turbulence by Menter along with the γ–Reθ (Gamma Re Theta) laminar-turbulent transition model; the Volume of Fluid method supplemented with the Schnerr–Sauer cavitation model is used to simulate the cavitation processes; a rotating propeller is simulated by a moving computational mesh and the GGI method to provide conformity of the solutions on adjacent boundaries of arbitrarily-shaped unstructured meshes of the two domains. The specific features of the numerical algorithms in use are described. The method validation results are given; they were obtained because of the problems of finding the performance curves of model-scale propellers in open water, namely the problems of finding the performance of propellers KP505 and IB without consideration of cavitation and the performance of propellers VP1304 and C5 under cavitation conditions. The paper demonstrates that the numerical simulation method presented allows for obtaining sufficiently accurate results to predict the main hydrodynamic characteristics for most modes of operation of the propellers.
该报告介绍了在俄罗斯LOGOS软件包中实现的方法，该方法使用网格生成器自动生成的非结构化计算网格对船舶螺旋桨流动问题进行数值模拟。该方法包括基于Navier-Stokes方程系统的计算模型，并根据物理过程编写:使用Reynolds平均Navier-Stokes方法和Menter湍流的k -ω SST模型以及γ-Reθ (Gamma Re Theta)层流-湍流过渡模型来计算瞬态点的湍流性质;采用流体体积法结合Schnerr-Sauer空化模型对空化过程进行模拟;采用运动计算网格和GGI方法对旋转螺旋桨进行仿真，以保证两域任意形状非结构化网格相邻边界上解的一致性。描述了所使用的数值算法的具体特点。给出了方法的验证结果;是由于在开阔水域中寻找模型级螺旋桨性能曲线的问题，即寻找不考虑空化的螺旋桨KP505和IB的性能以及空化条件下螺旋桨VP1304和C5的性能问题。本文表明，所提出的数值模拟方法可以获得足够精确的结果，以预测螺旋桨在大多数工作模式下的主要水动力特性。
{"title":"Numerical Approach Based on Solving 3D Navier–Stokes Equations for Simulation of the Marine Propeller Flow Problems","authors":"Andrey Kozelkov, Vadim Kurulin, Andrey Kurkin, Andrey Taranov, Kseniya Plygunova, Olga Krutyakova, Aleksey Korotkov","doi":"10.3390/fluids8110293","DOIUrl":"https://doi.org/10.3390/fluids8110293","url":null,"abstract":"The report presents the approach implemented in the Russian LOGOS software package for the numerical simulation of the marine propeller flow problems using unstructured computational meshes automatically generated by the mesh generator. This approach includes a computational model based on the Navier–Stokes equation system and written with respect to the physical process: the turbulent nature of flow with transient points is accounted using the Reynolds Averaged Navier–Stokes method and the k–ω SST model of turbulence by Menter along with the γ–Reθ (Gamma Re Theta) laminar-turbulent transition model; the Volume of Fluid method supplemented with the Schnerr–Sauer cavitation model is used to simulate the cavitation processes; a rotating propeller is simulated by a moving computational mesh and the GGI method to provide conformity of the solutions on adjacent boundaries of arbitrarily-shaped unstructured meshes of the two domains. The specific features of the numerical algorithms in use are described. The method validation results are given; they were obtained because of the problems of finding the performance curves of model-scale propellers in open water, namely the problems of finding the performance of propellers KP505 and IB without consideration of cavitation and the performance of propellers VP1304 and C5 under cavitation conditions. The paper demonstrates that the numerical simulation method presented allows for obtaining sufficiently accurate results to predict the main hydrodynamic characteristics for most modes of operation of the propellers.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135870933","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}
This paper investigates the adequacy of radial basis function (RBF)-based models as surrogates in uncertainty quantification (UQ) and CFD shape optimization; for the latter, problems with and without uncertainties are considered. In UQ, these are used to support the Monte Carlo, as well as, the non-intrusive, Gauss Quadrature and regression-based polynomial chaos expansion methods. They are applied to the flow around an isolated airfoil and a wing to quantify uncertainties associated with the constants of the γ−R˜eθt transition model and the surface roughness (in the 3D case); it is demonstrated that the use of the RBF-based surrogates leads to an up to 50% reduction in computational cost, compared with the same UQ method that uses CFD computations. In shape optimization under uncertainties, solved by stochastic search methods, RBF-based surrogates are used to compute statistical moments of the objective function. In applications with geometric uncertainties which are modeled through the Karhunen–Loève technique, the use on an RBF-based surrogate reduces the turnaround time of an evolutionary algorithm by orders of magnitude. In this type of applications, RBF networks are also used to perform mesh displacement for the perturbed geometries.
{"title":"Radial Basis Function Surrogates for Uncertainty Quantification and Aerodynamic Shape Optimization under Uncertainties","authors":"Varvara Asouti, Marina Kontou, Kyriakos Giannakoglou","doi":"10.3390/fluids8110292","DOIUrl":"https://doi.org/10.3390/fluids8110292","url":null,"abstract":"This paper investigates the adequacy of radial basis function (RBF)-based models as surrogates in uncertainty quantification (UQ) and CFD shape optimization; for the latter, problems with and without uncertainties are considered. In UQ, these are used to support the Monte Carlo, as well as, the non-intrusive, Gauss Quadrature and regression-based polynomial chaos expansion methods. They are applied to the flow around an isolated airfoil and a wing to quantify uncertainties associated with the constants of the γ−R˜eθt transition model and the surface roughness (in the 3D case); it is demonstrated that the use of the RBF-based surrogates leads to an up to 50% reduction in computational cost, compared with the same UQ method that uses CFD computations. In shape optimization under uncertainties, solved by stochastic search methods, RBF-based surrogates are used to compute statistical moments of the objective function. In applications with geometric uncertainties which are modeled through the Karhunen–Loève technique, the use on an RBF-based surrogate reduces the turnaround time of an evolutionary algorithm by orders of magnitude. In this type of applications, RBF networks are also used to perform mesh displacement for the perturbed geometries.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"33 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136022897","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}
We aim to develop a floor-cleaning design by exploiting oscillating bubbles combined with ambient pressure waves to clean various surfaces. Previous studies of this method in lab settings have proven its efficacy, but practical applications, especially concerning real-world conditions like dirt surfaces, remain largely unprobed. Our findings indicate that, excluding a configuration with a heavy mass bottom transducer, all tested configurations achieved approximately 60–70% cleaning performance. A slight improvement in cleaning performance was observed with the introduction of microbubbles, although it was within the error margin. Particularly noteworthy is the substantial reduction in water consumption in configurations with a water pocket, decreasing from 280 mL to a mere 3 mL, marking a significant step toward more environmentally sustainable cleaning practices, such as reduced water usage. This research provides implications for real-world cleaning applications, promising an eco-friendly and efficient cleaning alternative that reduces water usage and handles a variety of materials without causing damage.
{"title":"Ultrasonic Bubble Cleaner as a Sustainable Solution","authors":"Justin Howell, Emerson Ham, Sunghwan Jung","doi":"10.3390/fluids8110291","DOIUrl":"https://doi.org/10.3390/fluids8110291","url":null,"abstract":"We aim to develop a floor-cleaning design by exploiting oscillating bubbles combined with ambient pressure waves to clean various surfaces. Previous studies of this method in lab settings have proven its efficacy, but practical applications, especially concerning real-world conditions like dirt surfaces, remain largely unprobed. Our findings indicate that, excluding a configuration with a heavy mass bottom transducer, all tested configurations achieved approximately 60–70% cleaning performance. A slight improvement in cleaning performance was observed with the introduction of microbubbles, although it was within the error margin. Particularly noteworthy is the substantial reduction in water consumption in configurations with a water pocket, decreasing from 280 mL to a mere 3 mL, marking a significant step toward more environmentally sustainable cleaning practices, such as reduced water usage. This research provides implications for real-world cleaning applications, promising an eco-friendly and efficient cleaning alternative that reduces water usage and handles a variety of materials without causing damage.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136232286","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}
Manuel Ernani Cruz, Gabriel Lisbôa Verissimo, Filipe Leite Brandão, Albino José Kalab Leiroz
In this work, the influence of gas–solid drag and heat transfer coefficient models on the prediction capacity of the Euler–Euler approach to simulate reactive bubbling fluidized bed flows is studied. Three different cases are considered, a non-reactive bidisperse bubbling fluidized bed flow (Case 1), and two reactive polydisperse flows in bubbling fluidized beds, one for biomass gasification (Case 2), and the other for biomass pyrolysis (Case 3). The Gidaspow, Syamlal–O’Brien, and BVK gas–solid drag models and the Gunn, Ranz–Marshall, and Li–Mason gas–solid heat transfer correlations are investigated. A Eulerian multiphase approach in a two-dimensional Cartesian domain is employed for the simulations. Computational results for the three cases are compared with experimental data from the literature. The results obtained here contribute to a better understanding of the impacts of such closure models on the prediction ability of the Euler–Euler approach to simulate reactive flows. The results indicate that, for the simulation of reactive flows in bubbling fluidized bed reactors, the kinetic modeling of the reactions has a global effect, which superposes with the influence of the drag and heat transfer coefficient models. Nevertheless, local parameters can be noticeably affected by the choice of the interface closure models. Finally, this work also identifies the models that lead to the best results for the cases analyzed here, and thus proposes the use of such selected models for gasification and pyrolysis processes occurring in bubbling fluidized bed reactors.
{"title":"A Computational Study of the Influence of Drag Models and Heat Transfer Correlations on the Simulations of Reactive Polydisperse Flows in Bubbling Fluidized Beds","authors":"Manuel Ernani Cruz, Gabriel Lisbôa Verissimo, Filipe Leite Brandão, Albino José Kalab Leiroz","doi":"10.3390/fluids8110290","DOIUrl":"https://doi.org/10.3390/fluids8110290","url":null,"abstract":"In this work, the influence of gas–solid drag and heat transfer coefficient models on the prediction capacity of the Euler–Euler approach to simulate reactive bubbling fluidized bed flows is studied. Three different cases are considered, a non-reactive bidisperse bubbling fluidized bed flow (Case 1), and two reactive polydisperse flows in bubbling fluidized beds, one for biomass gasification (Case 2), and the other for biomass pyrolysis (Case 3). The Gidaspow, Syamlal–O’Brien, and BVK gas–solid drag models and the Gunn, Ranz–Marshall, and Li–Mason gas–solid heat transfer correlations are investigated. A Eulerian multiphase approach in a two-dimensional Cartesian domain is employed for the simulations. Computational results for the three cases are compared with experimental data from the literature. The results obtained here contribute to a better understanding of the impacts of such closure models on the prediction ability of the Euler–Euler approach to simulate reactive flows. The results indicate that, for the simulation of reactive flows in bubbling fluidized bed reactors, the kinetic modeling of the reactions has a global effect, which superposes with the influence of the drag and heat transfer coefficient models. Nevertheless, local parameters can be noticeably affected by the choice of the interface closure models. Finally, this work also identifies the models that lead to the best results for the cases analyzed here, and thus proposes the use of such selected models for gasification and pyrolysis processes occurring in bubbling fluidized bed reactors.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"282 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136231878","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}
Hassan Ali Ghazwani, Khairuddin Sanaullah, Vladimir Vladimirovich Sinitsin, Afrasyab Khan
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.
{"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}
Somaris E. Quintana, Maria Zuñiga-Navarro, David Ramirez-Brewer, Luis A. García-Zapateiro
The Cox and Merz rules are empirical correlations between the apparent viscosity of polymers with the effect of shear rate and the complex dynamic viscosity with the effect of frequency. In this study, the rheological properties of mayonnaise-type emulsions enriched with Averrhoa carambola extracts were investigated using small-amplitude oscillatory shear (SAOS) and steady shear flow. The results showed that the shear-thinning behavior of the samples was non-Newtonian with yield stress and had time-dependent characteristics, as evidenced by curves from non-oscillatory measurements. It was observed that the experimental data on the complex and apparent viscosity of the samples obeyed the Cox–Merz rule.
{"title":"Applicability of the Cox–Merz Relationship for Mayonnaise Enriched with Natural Extracts","authors":"Somaris E. Quintana, Maria Zuñiga-Navarro, David Ramirez-Brewer, Luis A. García-Zapateiro","doi":"10.3390/fluids8110287","DOIUrl":"https://doi.org/10.3390/fluids8110287","url":null,"abstract":"The Cox and Merz rules are empirical correlations between the apparent viscosity of polymers with the effect of shear rate and the complex dynamic viscosity with the effect of frequency. In this study, the rheological properties of mayonnaise-type emulsions enriched with Averrhoa carambola extracts were investigated using small-amplitude oscillatory shear (SAOS) and steady shear flow. The results showed that the shear-thinning behavior of the samples was non-Newtonian with yield stress and had time-dependent characteristics, as evidenced by curves from non-oscillatory measurements. It was observed that the experimental data on the complex and apparent viscosity of the samples obeyed the Cox–Merz rule.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":"17 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136264080","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}
Michael Gerard Connolly, Malachy J. O’Rourke, Alojz Ivankovic
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.
{"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}
Parag Gupta, David MacTaggart, Radostin D. Simitev
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.
{"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}
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