Pub Date : 2022-09-19DOI: 10.37394/232013.2022.17.15
J. Nagler
This paper presents analytical adaptive expressions for the two distinct cases of tank leakage estimations for gas (sonic and subsonic) and liquid flows under specific measurements data that assists to evaluate a circular hole/slit/orifice (crack) diameter and area. The analytic process is performed by equalization between analytic reformulation of the traditional mass flow formulations and the test formulation for mass flow dependent driven pressure differential over time multiplied by volume. In case of uniform environment conditions, the slit diameter might also represent the total sum of numerous exit holes/slits possible existence. Finally, a qualitative agreement was found between literature and current results in the context of orifice diameter versus pressure differential.
{"title":"On Practical Gas and Liquid Leakage Diameter Analytic Estimation for Vacuum Applications","authors":"J. Nagler","doi":"10.37394/232013.2022.17.15","DOIUrl":"https://doi.org/10.37394/232013.2022.17.15","url":null,"abstract":"This paper presents analytical adaptive expressions for the two distinct cases of tank leakage estimations for gas (sonic and subsonic) and liquid flows under specific measurements data that assists to evaluate a circular hole/slit/orifice (crack) diameter and area. The analytic process is performed by equalization between analytic reformulation of the traditional mass flow formulations and the test formulation for mass flow dependent driven pressure differential over time multiplied by volume. In case of uniform environment conditions, the slit diameter might also represent the total sum of numerous exit holes/slits possible existence. Finally, a qualitative agreement was found between literature and current results in the context of orifice diameter versus pressure differential.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48540629","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}
Pub Date : 2022-07-18DOI: 10.37394/232013.2022.17.13
F. Gallerano, F. Palleschi, Benedetta Iele, G. Cannata
We present a new three-dimensional numerical model for the simulation of breaking waves. In the proposed model, the integral contravariant form of the Navier-Stokes equations is expressed in a curvilinear moving coordinate system and are integrated by a predictor-corrector method. In the predictor step of the method, the equations of motion are discretized by a shock-capturing scheme that is based on an original highorder scheme for the reconstruction of the point values of the conserved variables on the faces of the computational grid. On the cell faces, the updating of the point values of the conserved variables is carried out by an exact Riemann solver. The final flow velocity field is obtained by a corrector step which is based exclusively on conserved variables, without the need of calculating an intermediate field of primitive variables. The new three-dimensional model significantly reduces the kinetic energy numerical dissipation introduced by the scheme. The proposed model is validated against experimental tests of breaking waves and is applied to the three-dimensional simulation of the local vortices produced by the interaction between the wave motion and an emerged barrier.
{"title":"A Three-dimensional High-order Numerical Model for the Simulation of the Interaction Between Waves and an Emerged Barrier","authors":"F. Gallerano, F. Palleschi, Benedetta Iele, G. Cannata","doi":"10.37394/232013.2022.17.13","DOIUrl":"https://doi.org/10.37394/232013.2022.17.13","url":null,"abstract":"We present a new three-dimensional numerical model for the simulation of breaking waves. In the proposed model, the integral contravariant form of the Navier-Stokes equations is expressed in a curvilinear moving coordinate system and are integrated by a predictor-corrector method. In the predictor step of the method, the equations of motion are discretized by a shock-capturing scheme that is based on an original highorder scheme for the reconstruction of the point values of the conserved variables on the faces of the computational grid. On the cell faces, the updating of the point values of the conserved variables is carried out by an exact Riemann solver. The final flow velocity field is obtained by a corrector step which is based exclusively on conserved variables, without the need of calculating an intermediate field of primitive variables. The new three-dimensional model significantly reduces the kinetic energy numerical dissipation introduced by the scheme. The proposed model is validated against experimental tests of breaking waves and is applied to the three-dimensional simulation of the local vortices produced by the interaction between the wave motion and an emerged barrier.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43297943","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}
Pub Date : 2022-07-12DOI: 10.37394/232013.2022.17.12
Y. D. Dwivedi, S. Y B, B. Sunil, CH. V. K. N. S. N. Moorthy, K. V. Allamraju
In this study, the effects of variations in the parametric geometry on the aerodynamic efficiency and longitudinal static stability of a bio-inspired airfoil were assessed using the computational method at a low Reynolds number of 80000. The investigation aims to recognize the influence of corrugations on aerodynamic forces and moments and compare them with a non-corrugated profile having similar geometry without corrugations. Three different airfoils were chosen, the first triangular peaked corrugated is inspired from the mid-section of a dragonfly wing, the second modified simplified corrugated is a different form of the dragonfly wing section, which was modified to match the maximum thickness of the first airfoil, and the third is a non-corrugated Hybrid airfoil obtained by joining the peaks of the second airfoil. These three models were fabricated using an additive manufacturing process to undertake the experimental work in a low subsonic wind tunnel to find aerodynamic characteristics. ANSYS FLUENT solver was applied to unravel the steady, laminar, incompressible, two-dimensional, RANS equations. The tests were performed for 4 to +20 degrees angle of attack at a Reynolds number of 80,000. The result revealed that the Hybrid airfoil is suitable only for up to a 4-degree angle of attack. The modified simple corrugated airfoil produced significant aerodynamic performance at high angles of attack than the other two tested airfoils. The flow field study also showed the same results. Results are validated with experimental work and also with existing literature.
{"title":"Numerical Study of Bio-Inspired Corrugated Airfoil Geometry in a Forward Flight at a Low Reynolds Number","authors":"Y. D. Dwivedi, S. Y B, B. Sunil, CH. V. K. N. S. N. Moorthy, K. V. Allamraju","doi":"10.37394/232013.2022.17.12","DOIUrl":"https://doi.org/10.37394/232013.2022.17.12","url":null,"abstract":"In this study, the effects of variations in the parametric geometry on the aerodynamic efficiency and longitudinal static stability of a bio-inspired airfoil were assessed using the computational method at a low Reynolds number of 80000. The investigation aims to recognize the influence of corrugations on aerodynamic forces and moments and compare them with a non-corrugated profile having similar geometry without corrugations. Three different airfoils were chosen, the first triangular peaked corrugated is inspired from the mid-section of a dragonfly wing, the second modified simplified corrugated is a different form of the dragonfly wing section, which was modified to match the maximum thickness of the first airfoil, and the third is a non-corrugated Hybrid airfoil obtained by joining the peaks of the second airfoil. These three models were fabricated using an additive manufacturing process to undertake the experimental work in a low subsonic wind tunnel to find aerodynamic characteristics. ANSYS FLUENT solver was applied to unravel the steady, laminar, incompressible, two-dimensional, RANS equations. The tests were performed for 4 to +20 degrees angle of attack at a Reynolds number of 80,000. The result revealed that the Hybrid airfoil is suitable only for up to a 4-degree angle of attack. The modified simple corrugated airfoil produced significant aerodynamic performance at high angles of attack than the other two tested airfoils. The flow field study also showed the same results. Results are validated with experimental work and also with existing literature.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45414678","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}
Pub Date : 2022-06-28DOI: 10.37394/232013.2022.17.10
Fayçal Chergui, M. Bouzit
The objective of the current paper is to study the propagating and breaking of solitary waves on stepped slopes beaches, to simulate the shoaling and breaking, specifically the location of breaking point Xb, and solitary wave height at breaking Hb of solitary waves on the different stepped slopes. Ansys Fluent is used to implement the simulation, a two-dimensional volume of fluid (VOF) which is based on the Reynolds-Averaged Navier–Stokes (RANS) equations and the k–ε turbulence closure solver. The obtained results were firstly validated with existing empirical formulas for solitary wave run-up on the slope without stepped structure and are compared with the experimental and numerical results. The numerical computation has been carried out for several, configurations of beach slopes with tan ß= 1:15, 1:20, 1:25, wave height H0= 0.04, 0.06, 0.08m, water depth h0= 0.15, 0.2, 0.25m, and step height Sh= 0.025, 0.05, 0.075m. A set of numerical simulations were implemented to analyze shoaling and breaking of solitary waves, wave reflection, wave transmission, and wave run-up with various parameters wave heights, water depth, beach slopes, and Sh step height.
{"title":"Numerical Simulation of Solitary Waves Propagating on Stepped Slopes Beaches","authors":"Fayçal Chergui, M. Bouzit","doi":"10.37394/232013.2022.17.10","DOIUrl":"https://doi.org/10.37394/232013.2022.17.10","url":null,"abstract":"The objective of the current paper is to study the propagating and breaking of solitary waves on stepped slopes beaches, to simulate the shoaling and breaking, specifically the location of breaking point Xb, and solitary wave height at breaking Hb of solitary waves on the different stepped slopes. Ansys Fluent is used to implement the simulation, a two-dimensional volume of fluid (VOF) which is based on the Reynolds-Averaged Navier–Stokes (RANS) equations and the k–ε turbulence closure solver. The obtained results were firstly validated with existing empirical formulas for solitary wave run-up on the slope without stepped structure and are compared with the experimental and numerical results. The numerical computation has been carried out for several, configurations of beach slopes with tan ß= 1:15, 1:20, 1:25, wave height H0= 0.04, 0.06, 0.08m, water depth h0= 0.15, 0.2, 0.25m, and step height Sh= 0.025, 0.05, 0.075m. A set of numerical simulations were implemented to analyze shoaling and breaking of solitary waves, wave reflection, wave transmission, and wave run-up with various parameters wave heights, water depth, beach slopes, and Sh step height.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42692497","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}
Pub Date : 2022-04-21DOI: 10.37394/232013.2022.17.7
D. Roach, M. Hamdan
The slip hypothesis and the interfacial condition of Beavers and Joseph are discussed in this work, which reports on extensions of this condition to flow through a free-space channel over non-Darcy porous layers, flow through composite porous layers, and flow of pressure-dependent fluids through and over porous layers. Expressions for velocities at the interface and relationships between slip parameters are obtained.
{"title":"Interfacial Velocities, Slip Parameters and Other Theoretical Expressions Arising in the Beavers and Joseph Condition","authors":"D. Roach, M. Hamdan","doi":"10.37394/232013.2022.17.7","DOIUrl":"https://doi.org/10.37394/232013.2022.17.7","url":null,"abstract":"The slip hypothesis and the interfacial condition of Beavers and Joseph are discussed in this work, which reports on extensions of this condition to flow through a free-space channel over non-Darcy porous layers, flow through composite porous layers, and flow of pressure-dependent fluids through and over porous layers. Expressions for velocities at the interface and relationships between slip parameters are obtained.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42989297","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}
Pub Date : 2022-03-26DOI: 10.37394/232013.2022.17.6
B. Suyitno, R. Rahman, Ismail Ismail, E. A. Pane
The development of wind energy systems has achieved a higher technology readiness level for Horizontal Axis Wind Turbine (HAWT). Unfortunately, the HAWT is only suitable for high wind speed areas. The Vertical Axis Wind Turbine (VAWT) is considered the ideal model to utilize wind energy in the low wind speed region. However, VAWT has a lower power coefficient. Therefore, developing a VAWT wind farm can improve the overall energy density for power generation in the low wind speed region. In this study, staggered configuration for three turbine clusters is evaluated through numerical simulation and experimental tests. The pitch distance is set by using the rotor's diameter as a reference for placing the 3rd rotor at the second row. The turbulence intensity in the area wake superposition is highly affected by the position of the 3rd rotor. The flow characteristic indicates that the 3D layout has a high concentration at the front area of the 3rd rotor. It leads to higher achievement of power ratio for the clusters. The overall power ratio for 3D layout can achieve more than 0.9, whereas, at a speed 3 m/s, the highest power ratio is obtained at 1.0. The finding in this study can be set as an essential reference for developing a VAWT wind farm with a specific arrangement and improving the overall power density of the turbine clusters.
{"title":"Increasing the Energy Density and Power Ratio of a Staggered VAWT Wind Farm by Using the Rotor's Diameter as a Reference","authors":"B. Suyitno, R. Rahman, Ismail Ismail, E. A. Pane","doi":"10.37394/232013.2022.17.6","DOIUrl":"https://doi.org/10.37394/232013.2022.17.6","url":null,"abstract":"The development of wind energy systems has achieved a higher technology readiness level for Horizontal Axis Wind Turbine (HAWT). Unfortunately, the HAWT is only suitable for high wind speed areas. The Vertical Axis Wind Turbine (VAWT) is considered the ideal model to utilize wind energy in the low wind speed region. However, VAWT has a lower power coefficient. Therefore, developing a VAWT wind farm can improve the overall energy density for power generation in the low wind speed region. In this study, staggered configuration for three turbine clusters is evaluated through numerical simulation and experimental tests. The pitch distance is set by using the rotor's diameter as a reference for placing the 3rd rotor at the second row. The turbulence intensity in the area wake superposition is highly affected by the position of the 3rd rotor. The flow characteristic indicates that the 3D layout has a high concentration at the front area of the 3rd rotor. It leads to higher achievement of power ratio for the clusters. The overall power ratio for 3D layout can achieve more than 0.9, whereas, at a speed 3 m/s, the highest power ratio is obtained at 1.0. The finding in this study can be set as an essential reference for developing a VAWT wind farm with a specific arrangement and improving the overall power density of the turbine clusters.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46471025","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}
Pub Date : 2022-03-24DOI: 10.37394/232013.2022.17.5
Chasiotis Vasileios, Tachos Nikolaos, Filios Andronikos
The objective of the current computational study is to predict the performance output of a modified two-bucket Savonius rotor. Each bucket consists of three arc-type blades of different radius which is determined by the slot width ratio, in the range of 0.05 to 0.15 and the slot central angle, in the range of 0 to 20 deg. Nine configurations are designed with a fixed rotor diameter and a variable slot width and slot central angle, aiming to resolve the performance output and investigate the effect of the two previous parameters on the power and the static torque coefficients. The commercial CFD package Fluent® is used to solve the unsteady Reynolds-Averaged Navier-Stokes equations, along with Spalart-Allmaras turbulence model. Initially, a standard Savonius rotor, was used to validate the computational procedure using experimental results available in literature. Next, the same validated model is used to resolve the designed slotted bucket configurations. The performance of the examined slotted bucket configurations indicates improved self-starting characteristics, but a lower power coefficient compared with the solid bucket Savonius rotor. Lower values of slot width ratio have improved output performance while the slot central angle, does not greatly affect the overall performance of slotted bucket rotor
当前计算研究的目的是预测改进的双桶萨沃纽斯转子的性能输出。每个铲斗由3个半径不同的圆弧型叶片组成，圆弧型叶片的半径由槽宽比(0.05 ~ 0.15)和槽圆心角(0 ~ 20°)决定。设计了固定转子直径、可变槽宽和槽圆心角的9种配置，旨在解决性能输出问题，并研究了前两种参数对功率和静扭矩系数的影响。商用CFD软件包Fluent®用于求解非定常reynolds - average Navier-Stokes方程以及Spalart-Allmaras湍流模型。最初，一个标准的萨沃纽斯转子，被用来验证计算过程中使用的实验结果在文献中可用。接下来，使用相同的验证模型来求解设计的开槽桶配置。所研究的槽斗结构的性能表明，自启动特性有所改善，但与固体桶Savonius转子相比，功率系数较低。较小的槽宽比提高了转子的输出性能，而较小的槽中心角对槽斗转子的整体性能影响不大
{"title":"Computational Performance Analysis of a Two-slotted Bucket Savonius Rotor","authors":"Chasiotis Vasileios, Tachos Nikolaos, Filios Andronikos","doi":"10.37394/232013.2022.17.5","DOIUrl":"https://doi.org/10.37394/232013.2022.17.5","url":null,"abstract":"The objective of the current computational study is to predict the performance output of a modified two-bucket Savonius rotor. Each bucket consists of three arc-type blades of different radius which is determined by the slot width ratio, in the range of 0.05 to 0.15 and the slot central angle, in the range of 0 to 20 deg. Nine configurations are designed with a fixed rotor diameter and a variable slot width and slot central angle, aiming to resolve the performance output and investigate the effect of the two previous parameters on the power and the static torque coefficients. The commercial CFD package Fluent® is used to solve the unsteady Reynolds-Averaged Navier-Stokes equations, along with Spalart-Allmaras turbulence model. Initially, a standard Savonius rotor, was used to validate the computational procedure using experimental results available in literature. Next, the same validated model is used to resolve the designed slotted bucket configurations. The performance of the examined slotted bucket configurations indicates improved self-starting characteristics, but a lower power coefficient compared with the solid bucket Savonius rotor. Lower values of slot width ratio have improved output performance while the slot central angle, does not greatly affect the overall performance of slotted bucket rotor","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42519534","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}
Pub Date : 2022-03-08DOI: 10.37394/232013.2022.17.4
Raffaele Solari, P. Bagnerini, G. Vernengo
The hydrodynamics performance of submerged and surface-piercing lifting bodies is analyzed by a potential flow model based on a Vortex Lattice Method (VLM). Such a numerical scheme, widely applied in aerodynamics, is particularly suitable to model the lifting effects thanks to the vortex distribution used to discretize the boundaries of the lifting bodies. The method has been developed with specific boundary conditions to account for the development of steady free surface wave patterns. Both submerged bodies, such as flat plates and hydrofoils, as well as planing hulls can be studied. The method is validated by comparison against available experimental data and other Computational Fluid Dynamic (CFD) results from Reynolds Averaged Navier Stokes (RANS) approaches. In all the analyzed cases, namely 2D and 3D flat plates, a NACA hydrofoil, planning flat plates and prismatic planing hulls, results have been found to be consistent with those taken as reference. The obtained hydrodynamic predictionsare discussed highlighting the advantages and the possible improvements of the developed approach.
{"title":"A Vortex Lattice Method for the Hydrodynamic Solution of Lifting Bodies Traveling Close and Across a Free Surface","authors":"Raffaele Solari, P. Bagnerini, G. Vernengo","doi":"10.37394/232013.2022.17.4","DOIUrl":"https://doi.org/10.37394/232013.2022.17.4","url":null,"abstract":"The hydrodynamics performance of submerged and surface-piercing lifting bodies is analyzed by a potential flow model based on a Vortex Lattice Method (VLM). Such a numerical scheme, widely applied in aerodynamics, is particularly suitable to model the lifting effects thanks to the vortex distribution used to discretize the boundaries of the lifting bodies. The method has been developed with specific boundary conditions to account for the development of steady free surface wave patterns. Both submerged bodies, such as flat plates and hydrofoils, as well as planing hulls can be studied. The method is validated by comparison against available experimental data and other Computational Fluid Dynamic (CFD) results from Reynolds Averaged Navier Stokes (RANS) approaches. In all the analyzed cases, namely 2D and 3D flat plates, a NACA hydrofoil, planning flat plates and prismatic planing hulls, results have been found to be consistent with those taken as reference. The obtained hydrodynamic predictionsare discussed highlighting the advantages and the possible improvements of the developed approach.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48338265","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}
Pub Date : 2022-03-03DOI: 10.37394/232013.2022.17.3
Mohammad Monfared A., Mohammad Mehdi Alishahi A., M. Alishahi
This paper presents an accurate blood flow model with tissue deformation of the human left ventricle, including the aortic valve. A two-way fluid-solid Interaction (FSI) algorithm is employed to simulate the performance of the human left ventricle during systole. The initial geometry of the left ventricle is extracted from CT scan images of a healthy person. The simulation results produced the systolic anterior motion of the Left Ventricle (LV) identical with the CT scan images at later times during systole. Besides, the numerical results for left ventricular volume change, maximum blood velocity at the aortic valve, and its maximum opening are in good agreement with physiological data. Although no clear image of the aortic valve is apparent in CT images, the FSI simulation predicted the maximum opening of the aortic valve to be 4.38 cm2 which is consistent with physiological observation on a healthy individual. As an application of the above algorithm, a model of Hypertrophic Cardiomyopathy (HCM) or septal wall thickening disease is constructed and studied during systole. This simulation provides an understanding of heart performance under HCM conditions. According to the simulation outcomes, the mitral valve approaches the septal wall under HCM due to the change in pressure gradient and the drag force on the mitral valve. This blockage of the LV blood passage by the mitral valve results in stagnation pressure loss and weaker hearth pumping power. Therefore, the maximum opening of the aortic valve, in this case, is 2.28 cm2, which is much lower than the physiological range, indicating the drastic effect of HCM on the performance of the aortic valve and systolic performance.
{"title":"Precise Fluid-Solid Simulation of Human Left Ventricle along with Aortic Valve during Systole","authors":"Mohammad Monfared A., Mohammad Mehdi Alishahi A., M. Alishahi","doi":"10.37394/232013.2022.17.3","DOIUrl":"https://doi.org/10.37394/232013.2022.17.3","url":null,"abstract":"This paper presents an accurate blood flow model with tissue deformation of the human left ventricle, including the aortic valve. A two-way fluid-solid Interaction (FSI) algorithm is employed to simulate the performance of the human left ventricle during systole. The initial geometry of the left ventricle is extracted from CT scan images of a healthy person. The simulation results produced the systolic anterior motion of the Left Ventricle (LV) identical with the CT scan images at later times during systole. Besides, the numerical results for left ventricular volume change, maximum blood velocity at the aortic valve, and its maximum opening are in good agreement with physiological data. Although no clear image of the aortic valve is apparent in CT images, the FSI simulation predicted the maximum opening of the aortic valve to be 4.38 cm2 which is consistent with physiological observation on a healthy individual. As an application of the above algorithm, a model of Hypertrophic Cardiomyopathy (HCM) or septal wall thickening disease is constructed and studied during systole. This simulation provides an understanding of heart performance under HCM conditions. According to the simulation outcomes, the mitral valve approaches the septal wall under HCM due to the change in pressure gradient and the drag force on the mitral valve. This blockage of the LV blood passage by the mitral valve results in stagnation pressure loss and weaker hearth pumping power. Therefore, the maximum opening of the aortic valve, in this case, is 2.28 cm2, which is much lower than the physiological range, indicating the drastic effect of HCM on the performance of the aortic valve and systolic performance.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49022838","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}
Pub Date : 2022-03-01DOI: 10.37394/232013.2022.17.2
Beaumont F., Bogard F., M. S., Polidori G. Matim
This preliminary study aimed to model the aerodynamic behavior of a large migratory bird during a forward flapping flight. Computational Fluid Dynamics (CFD) was used to model the flow around and in the wake of a Canada Goose flying at an altitude of 1000m and a speed of 13.9m/sec. Flapping of the wings was modeled through dynamic meshing and subroutines implemented in a computational code using the Finite Volumes method. Monitoring of the flow quantities during the unsteady calculation revealed a close relationship between the wing-flapping dynamics and the cyclic variation of the forces acting on the bird. Post-processing of the 3D results revealed a complex flow pattern mainly composed of two contra-rotating vortices developing at the wingtip. In a perpendicular plane to the main flow direction, we demonstrated that the bird's wake can be divided into two distinct zones: the downwash zone and the upwash zone. The latter is used by birds flying in formation to reduce their energy expenditure. We have also shown that when the bird flaps its wings, the trail of upwash left by the wingtips moves up and down in a wave-like motion. Further studies, which will include several birds, will be necessary to understand all the aerodynamic implications related to the flight of migratory birds in formation.
{"title":"Modeling of Three-dimensional Unsteady Wake Past a Large Migratory Bird during Flapping Flight","authors":"Beaumont F., Bogard F., M. S., Polidori G. Matim","doi":"10.37394/232013.2022.17.2","DOIUrl":"https://doi.org/10.37394/232013.2022.17.2","url":null,"abstract":"This preliminary study aimed to model the aerodynamic behavior of a large migratory bird during a forward flapping flight. Computational Fluid Dynamics (CFD) was used to model the flow around and in the wake of a Canada Goose flying at an altitude of 1000m and a speed of 13.9m/sec. Flapping of the wings was modeled through dynamic meshing and subroutines implemented in a computational code using the Finite Volumes method. Monitoring of the flow quantities during the unsteady calculation revealed a close relationship between the wing-flapping dynamics and the cyclic variation of the forces acting on the bird. Post-processing of the 3D results revealed a complex flow pattern mainly composed of two contra-rotating vortices developing at the wingtip. In a perpendicular plane to the main flow direction, we demonstrated that the bird's wake can be divided into two distinct zones: the downwash zone and the upwash zone. The latter is used by birds flying in formation to reduce their energy expenditure. We have also shown that when the bird flaps its wings, the trail of upwash left by the wingtips moves up and down in a wave-like motion. Further studies, which will include several birds, will be necessary to understand all the aerodynamic implications related to the flight of migratory birds in formation.","PeriodicalId":39418,"journal":{"name":"WSEAS Transactions on Fluid Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43852546","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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