Pub Date : 2023-04-14DOI: 10.1088/1873-7005/accd17
A. Elikashvili, E. Golbraikh
The formation and evolution of helical vortices in various media is an important hydrodynamic problem. A separate problem is the study of the behavior of the initial vortex, which is elevated above the surface. The evolution of such vortices is a complex multiparameter phenomenon. Based on a simple hydrodynamic model (or minimal model) in Elikashvili et al (2017 Phys. Fluids 29 026602) have been studied the formation of vorticity near the surface as a function of the initial height of the vortex and the Reynolds number. However, the influence of the parameters of the initial vortex profile on its evolution was not considered. In this paper, based on a simple hydrodynamic model, we study the evolution and formation of vortices near a solid surface for various initial vorticity profiles. The most widespread vortex profiles of Rankine, Burgers, and Vatistas were chosen for research. The simulation shows that the evolution of the vortex depends on its initial profile.
{"title":"The effect of elevated initial vortex shapes on its evolution","authors":"A. Elikashvili, E. Golbraikh","doi":"10.1088/1873-7005/accd17","DOIUrl":"https://doi.org/10.1088/1873-7005/accd17","url":null,"abstract":"The formation and evolution of helical vortices in various media is an important hydrodynamic problem. A separate problem is the study of the behavior of the initial vortex, which is elevated above the surface. The evolution of such vortices is a complex multiparameter phenomenon. Based on a simple hydrodynamic model (or minimal model) in Elikashvili et al (2017 Phys. Fluids 29 026602) have been studied the formation of vorticity near the surface as a function of the initial height of the vortex and the Reynolds number. However, the influence of the parameters of the initial vortex profile on its evolution was not considered. In this paper, based on a simple hydrodynamic model, we study the evolution and formation of vortices near a solid surface for various initial vorticity profiles. The most widespread vortex profiles of Rankine, Burgers, and Vatistas were chosen for research. The simulation shows that the evolution of the vortex depends on its initial profile.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48466683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-24DOI: 10.1088/1873-7005/acbedb
O. Sano
Viscous flow through macroscopic spherical cavities in a granular material is theoretically investigated. Number, size and configuration of the cavities are arbitrary, except that cavities are sufficiently distant to allow asymptotic analysis on their interaction, which is taken into account up to O(a/l)3 , where a and l are the characteristic radius and inter-cavity distance, respectively. Dependence of the flow field, flux into respective cavities and stress field etc on the cavity size, separation distance and orientation are analyzed. As further examples, 1D-, 2D-, and 3D-array of equal size cavities are examined, by which onset of the collapse of cavity and development of the collapsed region are elucidated. The latter may predict landslides and other flow-induced catastrophic changes in the material with quasi-equilibrium solid structure, as well as microscale waterway formation in human tissue known as angiogenesis.
{"title":"Viscous flow through macroscopic spherical cavities in an arbitrary configuration in a granular material","authors":"O. Sano","doi":"10.1088/1873-7005/acbedb","DOIUrl":"https://doi.org/10.1088/1873-7005/acbedb","url":null,"abstract":"Viscous flow through macroscopic spherical cavities in a granular material is theoretically investigated. Number, size and configuration of the cavities are arbitrary, except that cavities are sufficiently distant to allow asymptotic analysis on their interaction, which is taken into account up to O(a/l)3 , where a and l are the characteristic radius and inter-cavity distance, respectively. Dependence of the flow field, flux into respective cavities and stress field etc on the cavity size, separation distance and orientation are analyzed. As further examples, 1D-, 2D-, and 3D-array of equal size cavities are examined, by which onset of the collapse of cavity and development of the collapsed region are elucidated. The latter may predict landslides and other flow-induced catastrophic changes in the material with quasi-equilibrium solid structure, as well as microscale waterway formation in human tissue known as angiogenesis.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42134825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-10DOI: 10.1088/1873-7005/acbb22
Dawei Li, Kaibo Yu, X. Wang, Yuan-bo Gao
The effects of bump control on shock aerodynamic characteristics have been investigated by simulations. A bump control that based on the changes of local upper surface of two-dimensional (2D) airfoil or three-dimensional (3D) wing model has been applied to affect the shock intensity and position. The simulation results are close of other experiment when the calculate parameters are same with each other. The simulations show that the drag and lift characteristics can be improved with the bump control, and the results of improvement strongly depend on control parameters. For the 2D RAE2822 airfoil, the optimal control position of the bump control must keep close to the position of the shock wave. The 3D local bump that located on 80% wing span wise and closed to the tip can acquire a batter control results for the 3D RAE2822 wing model.
{"title":"Numerical analysis of shock characteristics control based on bump","authors":"Dawei Li, Kaibo Yu, X. Wang, Yuan-bo Gao","doi":"10.1088/1873-7005/acbb22","DOIUrl":"https://doi.org/10.1088/1873-7005/acbb22","url":null,"abstract":"The effects of bump control on shock aerodynamic characteristics have been investigated by simulations. A bump control that based on the changes of local upper surface of two-dimensional (2D) airfoil or three-dimensional (3D) wing model has been applied to affect the shock intensity and position. The simulation results are close of other experiment when the calculate parameters are same with each other. The simulations show that the drag and lift characteristics can be improved with the bump control, and the results of improvement strongly depend on control parameters. For the 2D RAE2822 airfoil, the optimal control position of the bump control must keep close to the position of the shock wave. The 3D local bump that located on 80% wing span wise and closed to the tip can acquire a batter control results for the 3D RAE2822 wing model.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44128505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-08DOI: 10.1088/1873-7005/acba44
I. Farahbakhsh, Amin Paknejad, H. Ghassemi
A monolithic mathematical framework for understanding the fluid–rigid–elastic structure interaction problem is proposed. A numerical method in a secondary formulation of the Navier–Stokes equations accompanying a technique for imposing the rigid boundaries is applied. The one-fluid formulation of the incompressible Navier–Stokes equation, containing the terms governing the elastic structure, is transformed into the vorticity-stream function formulation. The rigid structure is imposed in the flow field based on the velocity–vorticity kinematic relation and harmonic function theorem. The vorticity, level-set function, and left Cauchy–Green deformation tensor are updated utilizing three transport equations to investigate the evolution of the velocity field, elastic structure(s) configuration, and elastic stress tensor. The method is implemented to solve three challenging problems, and the results show its capabilities in proper imposing the rigid structures in the flow field and also the simultaneous modeling the rigid and elastic structure interactions with incompressible fluid flow.
{"title":"A full-Eulerian approach for simulation of a system of fluid–rigid–elastic structure interaction based on the vorticity-stream function formulation","authors":"I. Farahbakhsh, Amin Paknejad, H. Ghassemi","doi":"10.1088/1873-7005/acba44","DOIUrl":"https://doi.org/10.1088/1873-7005/acba44","url":null,"abstract":"A monolithic mathematical framework for understanding the fluid–rigid–elastic structure interaction problem is proposed. A numerical method in a secondary formulation of the Navier–Stokes equations accompanying a technique for imposing the rigid boundaries is applied. The one-fluid formulation of the incompressible Navier–Stokes equation, containing the terms governing the elastic structure, is transformed into the vorticity-stream function formulation. The rigid structure is imposed in the flow field based on the velocity–vorticity kinematic relation and harmonic function theorem. The vorticity, level-set function, and left Cauchy–Green deformation tensor are updated utilizing three transport equations to investigate the evolution of the velocity field, elastic structure(s) configuration, and elastic stress tensor. The method is implemented to solve three challenging problems, and the results show its capabilities in proper imposing the rigid structures in the flow field and also the simultaneous modeling the rigid and elastic structure interactions with incompressible fluid flow.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44414067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-13DOI: 10.1088/1873-7005/acb2f7
Z. Malecha
The article presents a three-dimensional numerical study of the large-amplitude, acoustically driven streaming flow in rectangular resonator for different frequencies of the acoustic wave and different temperature regime, isothermal and 60 K temperature difference between the top and bottom walls. The utilized numerical model was based on the Navier–Stokes compressible equations, the ideal gas model, and finite volume discretization. The oscillating wall of the resonator was modeled as a dynamically moving boundary of the numerical domain. The size of the resonators was adjusted to fit one period of the acoustic wave. The research revealed a stationary pair of streaming vortices in the resonator with a characteristic three-dimensional structure. Their intensity was much greater in the case of nonisothermal flow. The study of the impact of side walls on the intensity of streaming revealed its gradual decrease with approaching the walls, creating a quasiparabolic profile in the resonator. Interestingly, the relationship between the intensity of streaming and the frequency of the acoustic wave turned out to be not trivial and two maxima for different frequencies could be observed.
{"title":"Three-dimensional numerical study of acoustic streaming phenomenon in rectangular resonator","authors":"Z. Malecha","doi":"10.1088/1873-7005/acb2f7","DOIUrl":"https://doi.org/10.1088/1873-7005/acb2f7","url":null,"abstract":"The article presents a three-dimensional numerical study of the large-amplitude, acoustically driven streaming flow in rectangular resonator for different frequencies of the acoustic wave and different temperature regime, isothermal and 60 K temperature difference between the top and bottom walls. The utilized numerical model was based on the Navier–Stokes compressible equations, the ideal gas model, and finite volume discretization. The oscillating wall of the resonator was modeled as a dynamically moving boundary of the numerical domain. The size of the resonators was adjusted to fit one period of the acoustic wave. The research revealed a stationary pair of streaming vortices in the resonator with a characteristic three-dimensional structure. Their intensity was much greater in the case of nonisothermal flow. The study of the impact of side walls on the intensity of streaming revealed its gradual decrease with approaching the walls, creating a quasiparabolic profile in the resonator. Interestingly, the relationship between the intensity of streaming and the frequency of the acoustic wave turned out to be not trivial and two maxima for different frequencies could be observed.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44692949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-09DOI: 10.1088/1873-7005/acb170
R. Baños, J. Arcos, O. Bautista, F. Méndez
We conduct a numerical study of viscoelectric and steric effects on an oscillatory electroosmotic flow (OEOF) and their impact on the mass transport of a passive solute through a hydrophobic microchannel. In many applications of electroosmosis, zeta potentials as high as 100–200 mV can be found; in such a situation, the Debye–Hückel approximation is no longer valid, and the steric effect must be considered because the crowding of finite-sized ions close to the microchannel walls. In addition to the previous effect, the local viscosity can be increased due to the viscoelectric effect for strong electric potentials induced in the electric double layer. Earlier works have studied the mass transfer caused by an OEOF; however, the combined effects’ influence has not been considered. This research suggests that under an appropriate combination of the viscoelectric and steric effects, together with the microchannel hydrophobicity, the mass transport can be controlled and notably enhanced compared with the case where such effects are disregarded. An interesting behavior occurs for relatively high values of the steric factor ν, where there is a linear dependence between the mass transport Q˜ and the viscoelectric factor f˜ ; in contrast, for low values of ν, the relationship Q˜−f˜ is non-linear.
{"title":"Mass transport in oscillatory electroosmotic viscoelectric flow in a hydrophobic microchannel with steric effect","authors":"R. Baños, J. Arcos, O. Bautista, F. Méndez","doi":"10.1088/1873-7005/acb170","DOIUrl":"https://doi.org/10.1088/1873-7005/acb170","url":null,"abstract":"We conduct a numerical study of viscoelectric and steric effects on an oscillatory electroosmotic flow (OEOF) and their impact on the mass transport of a passive solute through a hydrophobic microchannel. In many applications of electroosmosis, zeta potentials as high as 100–200 mV can be found; in such a situation, the Debye–Hückel approximation is no longer valid, and the steric effect must be considered because the crowding of finite-sized ions close to the microchannel walls. In addition to the previous effect, the local viscosity can be increased due to the viscoelectric effect for strong electric potentials induced in the electric double layer. Earlier works have studied the mass transfer caused by an OEOF; however, the combined effects’ influence has not been considered. This research suggests that under an appropriate combination of the viscoelectric and steric effects, together with the microchannel hydrophobicity, the mass transport can be controlled and notably enhanced compared with the case where such effects are disregarded. An interesting behavior occurs for relatively high values of the steric factor ν, where there is a linear dependence between the mass transport Q˜ and the viscoelectric factor f˜ ; in contrast, for low values of ν, the relationship Q˜−f˜ is non-linear.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43273482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-03DOI: 10.1088/1873-7005/acafa1
L. R. Scott
We consider the general problem of matching rheological models to experiments. We introduce the concept of identifiability of models from a given set of experiments. To illustrate this in detail, we study two rheology models, the grade-two and Oldroyd 3-parameter models, and consider two hypothetical rheometers to see if the coefficients of the rheology models are identifiable from experimental measurements or not. For the Oldroyd models, we show that the coefficients can be estimated from experiments from the two rheometers. But for the grade-two model, it is not possible to distinguish the two nonNewtonian parameters, only their sum can be estimated, and thus the grade-two model is not identifiable by the two hypothetical rheometers. However, our results imply that a different rheometer may be able to do that.
{"title":"Rheology, rheometers, and matching models to experiments","authors":"L. R. Scott","doi":"10.1088/1873-7005/acafa1","DOIUrl":"https://doi.org/10.1088/1873-7005/acafa1","url":null,"abstract":"We consider the general problem of matching rheological models to experiments. We introduce the concept of identifiability of models from a given set of experiments. To illustrate this in detail, we study two rheology models, the grade-two and Oldroyd 3-parameter models, and consider two hypothetical rheometers to see if the coefficients of the rheology models are identifiable from experimental measurements or not. For the Oldroyd models, we show that the coefficients can be estimated from experiments from the two rheometers. But for the grade-two model, it is not possible to distinguish the two nonNewtonian parameters, only their sum can be estimated, and thus the grade-two model is not identifiable by the two hypothetical rheometers. However, our results imply that a different rheometer may be able to do that.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47786921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-03DOI: 10.1088/1873-7005/acafa0
Jian Wu, Yakun Liu, Di Zhang, Ze Cao, Zhuoyue Li
RANS simulations are performed for flow past rectangular cylinders with different elongation ratios (L/D= 1, 2, 4, 6, 8, 10, 12, 14 and 16) at Re= 22 000 using the k-ω SST turbulence model. As L/D increases from 1 to 6, stepwise increase of Strouhal number (St) exists, whereas an almost linear variation of St with respect to L/D can be found (St= 0.1618*L/D) at L/D⩾ 8. In the flow, two small secondary vortices beneath the shear layers are identified and the trailing-edge secondary vortex presents opposite rotational direction comparing with the leading-edge main vortex. Analysis of the shear layer and vortex characteristics is carried out to correlate with the wall normal stress and shear stress on the rectangular cylinder surfaces. Further, four coupling modes between leading-edge vortex (L-vortex) and trailing-edge vortex (T-vortex) among cylinders with different L/D are observed, named L-Vortex Mode (i.e. L/D= 1–2), L-T-Vortex Mode (i.e. L/D= 4–8), T-L-Vortex Mode (i.e. L/D= 10–14), and T-Vortex Mode (i.e. L/D ⩾ 16). When L/D > 4, the convective velocity of the L- and T-vortex is not sensitive to the L/D.
{"title":"Numerical simulation of vortex shedding from rectangular cylinders with different elongation ratios","authors":"Jian Wu, Yakun Liu, Di Zhang, Ze Cao, Zhuoyue Li","doi":"10.1088/1873-7005/acafa0","DOIUrl":"https://doi.org/10.1088/1873-7005/acafa0","url":null,"abstract":"RANS simulations are performed for flow past rectangular cylinders with different elongation ratios (L/D= 1, 2, 4, 6, 8, 10, 12, 14 and 16) at Re= 22 000 using the k-ω SST turbulence model. As L/D increases from 1 to 6, stepwise increase of Strouhal number (St) exists, whereas an almost linear variation of St with respect to L/D can be found (St= 0.1618*L/D) at L/D⩾ 8. In the flow, two small secondary vortices beneath the shear layers are identified and the trailing-edge secondary vortex presents opposite rotational direction comparing with the leading-edge main vortex. Analysis of the shear layer and vortex characteristics is carried out to correlate with the wall normal stress and shear stress on the rectangular cylinder surfaces. Further, four coupling modes between leading-edge vortex (L-vortex) and trailing-edge vortex (T-vortex) among cylinders with different L/D are observed, named L-Vortex Mode (i.e. L/D= 1–2), L-T-Vortex Mode (i.e. L/D= 4–8), T-L-Vortex Mode (i.e. L/D= 10–14), and T-Vortex Mode (i.e. L/D ⩾ 16). When L/D > 4, the convective velocity of the L- and T-vortex is not sensitive to the L/D.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42004071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-19DOI: 10.1088/1873-7005/acacc1
S. Kundu, Ravi Ranjan Sinha
The fractional operator in a space fractional advection-diffusion equation (FADE) plays a significant role in the mixing and vertical movement of sediment particles in a sediment-laden turbulent flow under non-local effects. Turbulent flow exhibits non-local mixing properties, which leads to the non-Fickian diffusion process that cannot be captured by the traditional diffusion equation. In this work, we present a generalized FADE that includes the generalized fractional differential operator in the Caputo sense. The full analytical solution is proposed utilizing the general Laplace transformation method. This generalized solution contains weight and scale functions and includes the effects of non-locality. It has been shown that several existing famous models of suspension concentration distribution for sediment particles (including both type-I and type-II distributions) in turbulent flows can be obtained from the proposed generalized solution with proper choices of the scale and weight functions in particular. Here a total of fourteen different types of concentration distribution equations including type-I and type-II profiles are derived from the general solution. Further possible generalizations of the model are also discussed which are more useful for practical applications. It is found that the several existing sediment distribution models are equivalent up to choices of weight and scale functions. Further, we found that the scale function could be physically related to the characteristic Lagrangian length of sediment mixing. The choice of the scale and weight function for both the type-I and type-II profiles are discussed and analyzed. Finally, the model is validated with experimental data as well as field data from the Missouri River, Mississippi River, and Rio Grande conveyance channels, and in each case, satisfactory agreements are obtained. These suggest the broader applicability of the present study.
{"title":"A unified model of suspension concentration distribution in sediment mixed turbulent flows using generalized fractional advection-diffusion equation","authors":"S. Kundu, Ravi Ranjan Sinha","doi":"10.1088/1873-7005/acacc1","DOIUrl":"https://doi.org/10.1088/1873-7005/acacc1","url":null,"abstract":"The fractional operator in a space fractional advection-diffusion equation (FADE) plays a significant role in the mixing and vertical movement of sediment particles in a sediment-laden turbulent flow under non-local effects. Turbulent flow exhibits non-local mixing properties, which leads to the non-Fickian diffusion process that cannot be captured by the traditional diffusion equation. In this work, we present a generalized FADE that includes the generalized fractional differential operator in the Caputo sense. The full analytical solution is proposed utilizing the general Laplace transformation method. This generalized solution contains weight and scale functions and includes the effects of non-locality. It has been shown that several existing famous models of suspension concentration distribution for sediment particles (including both type-I and type-II distributions) in turbulent flows can be obtained from the proposed generalized solution with proper choices of the scale and weight functions in particular. Here a total of fourteen different types of concentration distribution equations including type-I and type-II profiles are derived from the general solution. Further possible generalizations of the model are also discussed which are more useful for practical applications. It is found that the several existing sediment distribution models are equivalent up to choices of weight and scale functions. Further, we found that the scale function could be physically related to the characteristic Lagrangian length of sediment mixing. The choice of the scale and weight function for both the type-I and type-II profiles are discussed and analyzed. Finally, the model is validated with experimental data as well as field data from the Missouri River, Mississippi River, and Rio Grande conveyance channels, and in each case, satisfactory agreements are obtained. These suggest the broader applicability of the present study.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45874288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-15DOI: 10.1088/1873-7005/acabe3
E. Montes Gomez, D. Sumner
The mean wake of a three-dimensional surface-mounted rectangular flat plate was studied experimentally in a low-speed wind tunnel for four different aspect (height-to-width) ratios, AR = 3, 2, 1, and 0.5. The Reynolds number based on the plate width was Re = 3.8 × 104 and the boundary layer thickness on the ground plane, relative to the plate width, was δ/W = 1.1. The incidence angle of the plate was varied from α = 0° (where the plate is normal to the flow) to α = 90° (where the plate is parallel to the flow). The mean velocity and vorticity fields in the wake were measured using a seven-hole pressure probe. At α = 0°, the length of the recirculation zone behind the plate becomes progressively shorter as the aspect ratio is lowered and follows the same tendency as that of a finite square prism. The wakes of the slenderer flat plates of AR = 3 and 2 are characterised by two pairs of streamwise vortices: a pair of tip vortices in the upper wake and a pair of ground-plane vortices on the lower edges of the wake. With increasing incidence angle, a single tip vortex comes to dominate the wake, secondary vorticity is induced at various locations, a ‘traffic light’ vortex pattern may form, and ultimately a familiar wing-tip (trailing) vortex develops. In contrast, flow downstream of the less slender flat plates of AR = 1 and 0.5 is characterised by a single pair of large streamwise vortices, which become asymmetric with increasing incidence. Close to the flat plate of AR = 0.5, and at small incidence angles only, a unique pair of small inner vorticity concentrations, of opposite sense of rotation to the main streamwise vortices, is found in the upper part of the wake.
{"title":"The wake of a rectangular flat plate","authors":"E. Montes Gomez, D. Sumner","doi":"10.1088/1873-7005/acabe3","DOIUrl":"https://doi.org/10.1088/1873-7005/acabe3","url":null,"abstract":"The mean wake of a three-dimensional surface-mounted rectangular flat plate was studied experimentally in a low-speed wind tunnel for four different aspect (height-to-width) ratios, AR = 3, 2, 1, and 0.5. The Reynolds number based on the plate width was Re = 3.8 × 104 and the boundary layer thickness on the ground plane, relative to the plate width, was δ/W = 1.1. The incidence angle of the plate was varied from α = 0° (where the plate is normal to the flow) to α = 90° (where the plate is parallel to the flow). The mean velocity and vorticity fields in the wake were measured using a seven-hole pressure probe. At α = 0°, the length of the recirculation zone behind the plate becomes progressively shorter as the aspect ratio is lowered and follows the same tendency as that of a finite square prism. The wakes of the slenderer flat plates of AR = 3 and 2 are characterised by two pairs of streamwise vortices: a pair of tip vortices in the upper wake and a pair of ground-plane vortices on the lower edges of the wake. With increasing incidence angle, a single tip vortex comes to dominate the wake, secondary vorticity is induced at various locations, a ‘traffic light’ vortex pattern may form, and ultimately a familiar wing-tip (trailing) vortex develops. In contrast, flow downstream of the less slender flat plates of AR = 1 and 0.5 is characterised by a single pair of large streamwise vortices, which become asymmetric with increasing incidence. Close to the flat plate of AR = 0.5, and at small incidence angles only, a unique pair of small inner vorticity concentrations, of opposite sense of rotation to the main streamwise vortices, is found in the upper part of the wake.","PeriodicalId":56311,"journal":{"name":"Fluid Dynamics Research","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46036022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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