Pub Date : 2022-03-01DOI: 10.1080/14685248.2022.2037621
Fei Liao
This paper investigates the turbulent flow and aerodynamic noise of a half-cylinder body mounted on a flat plate at using high-order cell-centred finite difference method with delayed detached-eddy simulation (DDES) and large-eddy simulation (LES). Transient flow patterns from the two simulations are found to be very different in consideration of the small-scale structures. The profiles of mean velocity, resolved turbulent kinetic energy and resolved Reynolds shear stress are found to be similar among all the simulations, indicating mean quantities are relatively insensitive to turbulence modelling and grid resolution. The power spectra density of the pressure fluctuations show that LES is more capable of resolving energies in high-frequency range than DDES. After computing the normalised wavenumber-frequency spectra of fluctuating pressure on the window, we further carried out the wavenumber-frequency decomposition to separate the acoustic and the hydrodynamic components from the pressure fluctuations. The energy distribution shows that the acoustic energy has a much slower decaying rate in the high-frequency range than the hydrodynamic energy. In addition, the space-averaged sound pressure levels of pressure fluctuations on the window indicate that the present simulation with a high-order method is able to improve the accuracy in predicting pressure spectra. Finally, we carry out proper orthogonal decomposition to extract the dominating features of the decomposed acoustic and hydrodynamic components of pressure fluctuation. Patterns of multi-scale turbulence in hydrodynamic modes and propagating wavefronts of cylinder shape in acoustic modes are identified. The present research indicates that a relatively coarse grid is still capable of resolving fluctuating quantities of energy-containing structures, and LES is suggested against DDES when near-wall aerodynamic noise is the main concern.
{"title":"On turbulent flow and aerodynamic noise of generic side-view mirror with cell-centred finite difference method","authors":"Fei Liao","doi":"10.1080/14685248.2022.2037621","DOIUrl":"https://doi.org/10.1080/14685248.2022.2037621","url":null,"abstract":"This paper investigates the turbulent flow and aerodynamic noise of a half-cylinder body mounted on a flat plate at using high-order cell-centred finite difference method with delayed detached-eddy simulation (DDES) and large-eddy simulation (LES). Transient flow patterns from the two simulations are found to be very different in consideration of the small-scale structures. The profiles of mean velocity, resolved turbulent kinetic energy and resolved Reynolds shear stress are found to be similar among all the simulations, indicating mean quantities are relatively insensitive to turbulence modelling and grid resolution. The power spectra density of the pressure fluctuations show that LES is more capable of resolving energies in high-frequency range than DDES. After computing the normalised wavenumber-frequency spectra of fluctuating pressure on the window, we further carried out the wavenumber-frequency decomposition to separate the acoustic and the hydrodynamic components from the pressure fluctuations. The energy distribution shows that the acoustic energy has a much slower decaying rate in the high-frequency range than the hydrodynamic energy. In addition, the space-averaged sound pressure levels of pressure fluctuations on the window indicate that the present simulation with a high-order method is able to improve the accuracy in predicting pressure spectra. Finally, we carry out proper orthogonal decomposition to extract the dominating features of the decomposed acoustic and hydrodynamic components of pressure fluctuation. Patterns of multi-scale turbulence in hydrodynamic modes and propagating wavefronts of cylinder shape in acoustic modes are identified. The present research indicates that a relatively coarse grid is still capable of resolving fluctuating quantities of energy-containing structures, and LES is suggested against DDES when near-wall aerodynamic noise is the main concern.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"97 - 123"},"PeriodicalIF":1.9,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46137781","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 : 2022-02-27DOI: 10.1080/14685248.2022.2043552
D. Sarkar, E. Savory
A simple set of equations, capable of quantifying and predicting the spatial decay of freestream turbulence (FST) is derived in the current study. The prediction equations are based on the inviscid estimate of the turbulent kinetic energy (TKE) dissipation rate. The new set of model equations includes the integral length scale and the turbulent kinetic energy as variables and is superior to the previous set of decay equations because, unlike those, they are not dependent on any physical grid parameters (b or M). This new set of equations, when compared and validated against 17 sets (2 active grids, 2 multi-scale grids, 9 square-cross-sectioned grids and 4 circular cross-sectioned grids) of previous, well-accepted, experimental data, including those relating to grid-generated turbulence and covering a wide range of turbulent Reynolds number (ReLu 0) (7.5 × 101 to 6.9 × 104), where Lu 0 is the initial integral length scale, showed very good agreement (within ±15%). This set of correlation equations can be used to estimate the local and/or initial turbulent kinetic energy and integral length scale (Lu ) in an FST flow and to locate the region within a flow domain where nearly-constant turbulence conditions are expected to prevail.
{"title":"A prediction method for spatially decaying freestream turbulence","authors":"D. Sarkar, E. Savory","doi":"10.1080/14685248.2022.2043552","DOIUrl":"https://doi.org/10.1080/14685248.2022.2043552","url":null,"abstract":"A simple set of equations, capable of quantifying and predicting the spatial decay of freestream turbulence (FST) is derived in the current study. The prediction equations are based on the inviscid estimate of the turbulent kinetic energy (TKE) dissipation rate. The new set of model equations includes the integral length scale and the turbulent kinetic energy as variables and is superior to the previous set of decay equations because, unlike those, they are not dependent on any physical grid parameters (b or M). This new set of equations, when compared and validated against 17 sets (2 active grids, 2 multi-scale grids, 9 square-cross-sectioned grids and 4 circular cross-sectioned grids) of previous, well-accepted, experimental data, including those relating to grid-generated turbulence and covering a wide range of turbulent Reynolds number (ReLu 0) (7.5 × 101 to 6.9 × 104), where Lu 0 is the initial integral length scale, showed very good agreement (within ±15%). This set of correlation equations can be used to estimate the local and/or initial turbulent kinetic energy and integral length scale (Lu ) in an FST flow and to locate the region within a flow domain where nearly-constant turbulence conditions are expected to prevail.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"124 - 151"},"PeriodicalIF":1.9,"publicationDate":"2022-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41745909","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 : 2022-01-20DOI: 10.1080/14685248.2021.2009843
Rutuja A Chavan, Anurag Sharma, B. Kumar
In this work, experimental investigations have been pursued to analyse the Reynolds stress anisotropy in the flow around the bridge pier for no seepage and downward seepage. Experiments were conducted in the non-uniform sand bed channel with circular piers of 75 mm diameter. The streamwise velocity and Reynolds Shear Stress was observed to be maximum near the edge at upstream and near the bed at downstream of pier. The strength of reversal flow diminished with downward seepage. The turbulent kinetic energy at upstream of pier found to be decreased with seepage. Decreased Strouhal number with seepage indicates the diminishing strength of wake vortices. The results present the estimation of the deviation measure from the isotropic turbulence in terms of Reynolds stress tensor for whole flow depth (within and above the scour hole zone) at the upstream and downstream sections of the pier. The streamwise profile of anisotropy tensor within the scour hole zone of the upstream section demonstrates a lesser anisotropic stream in the presence of seepage flow, while transverse and vertical components of anisotropy tensor provide the higher anisotropic stream. The results are quite the opposite in the case of the downstream section of the pier. The present study also analysed the anisotropic invariant maps in terms of Lumley triangle, Eigenvalues, and the invariant functions for the whole flow depth. The anisotropic invariant maps inclining to be two-component isotropy within the scour hole zone for both the section of the pier. With the increase in flow depth that is at the edge of scour hole, the data sets of anisotropic invariant maps show a trend of one-component isotropy, while it has an affinity to develop three-component isotropy near the free surface. Invariant function measurement presents better two-component isotropy within the scour hole zone and quasi-three component isotropy in the outer zone of scour hole for the upstream section of pier. The experimental results provide a qualitative understanding of the evolution of the Reynolds stress anisotropy tensor in the pier-affected alluvial channel.
{"title":"Turbulence anisotropy around bridge piers in seepage affected sand bed channel","authors":"Rutuja A Chavan, Anurag Sharma, B. Kumar","doi":"10.1080/14685248.2021.2009843","DOIUrl":"https://doi.org/10.1080/14685248.2021.2009843","url":null,"abstract":"In this work, experimental investigations have been pursued to analyse the Reynolds stress anisotropy in the flow around the bridge pier for no seepage and downward seepage. Experiments were conducted in the non-uniform sand bed channel with circular piers of 75 mm diameter. The streamwise velocity and Reynolds Shear Stress was observed to be maximum near the edge at upstream and near the bed at downstream of pier. The strength of reversal flow diminished with downward seepage. The turbulent kinetic energy at upstream of pier found to be decreased with seepage. Decreased Strouhal number with seepage indicates the diminishing strength of wake vortices. The results present the estimation of the deviation measure from the isotropic turbulence in terms of Reynolds stress tensor for whole flow depth (within and above the scour hole zone) at the upstream and downstream sections of the pier. The streamwise profile of anisotropy tensor within the scour hole zone of the upstream section demonstrates a lesser anisotropic stream in the presence of seepage flow, while transverse and vertical components of anisotropy tensor provide the higher anisotropic stream. The results are quite the opposite in the case of the downstream section of the pier. The present study also analysed the anisotropic invariant maps in terms of Lumley triangle, Eigenvalues, and the invariant functions for the whole flow depth. The anisotropic invariant maps inclining to be two-component isotropy within the scour hole zone for both the section of the pier. With the increase in flow depth that is at the edge of scour hole, the data sets of anisotropic invariant maps show a trend of one-component isotropy, while it has an affinity to develop three-component isotropy near the free surface. Invariant function measurement presents better two-component isotropy within the scour hole zone and quasi-three component isotropy in the outer zone of scour hole for the upstream section of pier. The experimental results provide a qualitative understanding of the evolution of the Reynolds stress anisotropy tensor in the pier-affected alluvial channel.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"52 - 67"},"PeriodicalIF":1.9,"publicationDate":"2022-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45711250","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 : 2022-01-18DOI: 10.1080/14685248.2021.2014058
Gazi Hasanuzzaman, S. Merbold, V. Motuz, C. Egbers
Uniform blowing through a permeable surface acts as an active flow control method in wall bounded flows. Such control technique was investigated in a zero pressure gradient turbulent boundary layer over a flat plate. Measurement data were obtained with the help of Laser Doppler Anemometry technique. Besides the drag reduction characteristics of such flow control method, time averaged measurement of stream-wise and wall-normal velocity components was taken at Reynolds number based on momentum thickness ( ) of 1100–3670. Due to the difference in surface condition with and without blowing, mean properties of the boundary condition at wall influence the flow properties when scaled with outer scaling properties. Enhanced turbulence is observed in Reynolds stresses using statistical analysis including the thickening of the boundary layer.
{"title":"Enhanced outer peaks in turbulent boundary layer using uniform blowing at moderate Reynolds number","authors":"Gazi Hasanuzzaman, S. Merbold, V. Motuz, C. Egbers","doi":"10.1080/14685248.2021.2014058","DOIUrl":"https://doi.org/10.1080/14685248.2021.2014058","url":null,"abstract":"Uniform blowing through a permeable surface acts as an active flow control method in wall bounded flows. Such control technique was investigated in a zero pressure gradient turbulent boundary layer over a flat plate. Measurement data were obtained with the help of Laser Doppler Anemometry technique. Besides the drag reduction characteristics of such flow control method, time averaged measurement of stream-wise and wall-normal velocity components was taken at Reynolds number based on momentum thickness ( ) of 1100–3670. Due to the difference in surface condition with and without blowing, mean properties of the boundary condition at wall influence the flow properties when scaled with outer scaling properties. Enhanced turbulence is observed in Reynolds stresses using statistical analysis including the thickening of the boundary layer.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"68 - 95"},"PeriodicalIF":1.9,"publicationDate":"2022-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41314850","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 : 2022-01-03DOI: 10.1080/14685248.2022.2097688
R. Volino, W. Devenport, U. Piomelli
The prediction of turbulent flows over rough surfaces is important for many applications in engineering and in the natural sciences. Since the resolution of the roughness requires significant computational resources, most modelling approaches rely on the related concepts of ‘equivalent sand-grain roughness’ and ‘wall similarity’. While the validity of these concepts is well established for zero-pressure-gradient boundary-layers and for channel flows, such is not the case for non-equilibrium conditions. This raises a number of important questions, some of which are discussed in this paper. We also suggest some possible paths to answering these questions.
{"title":"Questions on the effects of roughness and its analysis in non-equilibrium flows","authors":"R. Volino, W. Devenport, U. Piomelli","doi":"10.1080/14685248.2022.2097688","DOIUrl":"https://doi.org/10.1080/14685248.2022.2097688","url":null,"abstract":"The prediction of turbulent flows over rough surfaces is important for many applications in engineering and in the natural sciences. Since the resolution of the roughness requires significant computational resources, most modelling approaches rely on the related concepts of ‘equivalent sand-grain roughness’ and ‘wall similarity’. While the validity of these concepts is well established for zero-pressure-gradient boundary-layers and for channel flows, such is not the case for non-equilibrium conditions. This raises a number of important questions, some of which are discussed in this paper. We also suggest some possible paths to answering these questions.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"454 - 466"},"PeriodicalIF":1.9,"publicationDate":"2022-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49162573","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 : 2021-12-04DOI: 10.1080/14685248.2021.2009842
Xuefang Xu, Huaishuang Shao, Ruixiong Li, Mei Lin, Peiming Shi
To investigate the crossflow of ventilation in high-speed train, a T-junction experimental setup is built and velocity data of crossflow under different conditions and positions are measured. Specifically, the conditions include the different velocities of crossflow and different intensities of suction, and the positions include upstream, mid-centre, and downstream. To give full information of the crossflow characteristics, the Holo-Hilbert spectral analysis (HHSA) method is used to analyse these velocity data. The results show that the components of frequency modulation (FM) and amplitude modulation (AM) can be found in the crossflow suffered from the suction. Furthermore, there exists an obvious difference between the crossflow with and without vanes. The crossflow without vanes has more components of FM modulation and AM modulation with high frequency. The increase of the velocity and velocity ratio both can influence the turbulent characteristics of crossflow, which presents high energy with a higher frequency of AM and FM. The crossflow at the upstream and the downstream has similar components presented in the AM–FM spectrum, while the crossflow at the mid-centre has more high-frequency components. In addition, the turbulent intensity at the mid-centre is inversely proportional to the distance from the suction.
{"title":"Investigation on turbulent characteristic of crossflow under suction in a T-junction using Holo-Hilbert spectral analysis","authors":"Xuefang Xu, Huaishuang Shao, Ruixiong Li, Mei Lin, Peiming Shi","doi":"10.1080/14685248.2021.2009842","DOIUrl":"https://doi.org/10.1080/14685248.2021.2009842","url":null,"abstract":"To investigate the crossflow of ventilation in high-speed train, a T-junction experimental setup is built and velocity data of crossflow under different conditions and positions are measured. Specifically, the conditions include the different velocities of crossflow and different intensities of suction, and the positions include upstream, mid-centre, and downstream. To give full information of the crossflow characteristics, the Holo-Hilbert spectral analysis (HHSA) method is used to analyse these velocity data. The results show that the components of frequency modulation (FM) and amplitude modulation (AM) can be found in the crossflow suffered from the suction. Furthermore, there exists an obvious difference between the crossflow with and without vanes. The crossflow without vanes has more components of FM modulation and AM modulation with high frequency. The increase of the velocity and velocity ratio both can influence the turbulent characteristics of crossflow, which presents high energy with a higher frequency of AM and FM. The crossflow at the upstream and the downstream has similar components presented in the AM–FM spectrum, while the crossflow at the mid-centre has more high-frequency components. In addition, the turbulent intensity at the mid-centre is inversely proportional to the distance from the suction.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"29 - 51"},"PeriodicalIF":1.9,"publicationDate":"2021-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41948231","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 : 2021-12-02DOI: 10.1080/14685248.2021.2007256
Mosedul Sarkar, S. Maurya, Partha P. Gopmandal, Sankar Sarkar
This article presents experimental results of turbulent flow measured in a bimodal degraded channel bed consisting of sand-gravel mixture. Sand and gravel of uniform sizes 0.25 and 3.5 mm were mixed in the same proportions (by weight) to create a bimodal sedimentary bed. A three-dimensional Vectrino velocimeter was employed to collect three-dimensional velocities over bimodal degraded bed under equilibrium condition. The streamwise velocity, Reynolds stresses, turbulent kinetic energy (TKE), and TKE fluxes profiles were compared with the literature. However, the advancement of the existing knowledge was done by exploring the laws of turbulence. To this end, the velocity structure function method was applied. Second and third-order streamwise velocity structure functions followed by mixed third-order velocity structure functions revealed the existence of inertial subrange. The TKE dissipation rate was estimated using Kolmogorov’s and Monin–Yaglom’s scaling laws of turbulence. The anisotropy analysis indicated anisotropic turbulence in the near-bed, whereas above the initial bed-level, the anisotropy tends to follow three-dimensional isotropy. The present study notably enhances the understanding of turbulent flow through a degraded bed by demonstrating the legitimacy of laws of turbulence at different locations over the bed and providing a comprehensible acquaintance in TKE budget and Reynolds stress anisotropy.
{"title":"Hydrodynamics of flow through a degraded channel bed","authors":"Mosedul Sarkar, S. Maurya, Partha P. Gopmandal, Sankar Sarkar","doi":"10.1080/14685248.2021.2007256","DOIUrl":"https://doi.org/10.1080/14685248.2021.2007256","url":null,"abstract":"This article presents experimental results of turbulent flow measured in a bimodal degraded channel bed consisting of sand-gravel mixture. Sand and gravel of uniform sizes 0.25 and 3.5 mm were mixed in the same proportions (by weight) to create a bimodal sedimentary bed. A three-dimensional Vectrino velocimeter was employed to collect three-dimensional velocities over bimodal degraded bed under equilibrium condition. The streamwise velocity, Reynolds stresses, turbulent kinetic energy (TKE), and TKE fluxes profiles were compared with the literature. However, the advancement of the existing knowledge was done by exploring the laws of turbulence. To this end, the velocity structure function method was applied. Second and third-order streamwise velocity structure functions followed by mixed third-order velocity structure functions revealed the existence of inertial subrange. The TKE dissipation rate was estimated using Kolmogorov’s and Monin–Yaglom’s scaling laws of turbulence. The anisotropy analysis indicated anisotropic turbulence in the near-bed, whereas above the initial bed-level, the anisotropy tends to follow three-dimensional isotropy. The present study notably enhances the understanding of turbulent flow through a degraded bed by demonstrating the legitimacy of laws of turbulence at different locations over the bed and providing a comprehensible acquaintance in TKE budget and Reynolds stress anisotropy.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"15 1-6","pages":"814 - 842"},"PeriodicalIF":1.9,"publicationDate":"2021-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41301324","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 : 2021-11-24DOI: 10.1080/14685248.2022.2067333
Ivan Girotto, R. Benzi, G. Di Staso, A. Scagliarini, S. Schifano, F. Toschi
Stabilised dense emulsions display a rich phenomenology connecting microstructure and rheology. In this work, we study how an emulsion with a finite yield stress can be built via large-scale stirring. By gradually increasing the volume fraction of the dispersed minority phase, under the constant action of a stirring force, we are able to achieve a volume fraction close to . Despite the fact that our system is highly concentrated and not yet turbulent we observe a droplet size distribution consistent with the scaling, often associated with inertial range droplets breakup. We report that the polydispersity of droplet sizes correlates with the dynamics of the emulsion formation process. Additionally, we quantify the visco-elastic properties of the dense emulsion finally obtained and we demonstrate the presence of a finite yield stress. The approach reported can pave the way to a quantitative understanding of the complex interplay between the dynamics of mesoscale constituents and the large-scale flow properties of yield stress fluids.
{"title":"Build up of yield stress fluids via chaotic emulsification","authors":"Ivan Girotto, R. Benzi, G. Di Staso, A. Scagliarini, S. Schifano, F. Toschi","doi":"10.1080/14685248.2022.2067333","DOIUrl":"https://doi.org/10.1080/14685248.2022.2067333","url":null,"abstract":"Stabilised dense emulsions display a rich phenomenology connecting microstructure and rheology. In this work, we study how an emulsion with a finite yield stress can be built via large-scale stirring. By gradually increasing the volume fraction of the dispersed minority phase, under the constant action of a stirring force, we are able to achieve a volume fraction close to . Despite the fact that our system is highly concentrated and not yet turbulent we observe a droplet size distribution consistent with the scaling, often associated with inertial range droplets breakup. We report that the polydispersity of droplet sizes correlates with the dynamics of the emulsion formation process. Additionally, we quantify the visco-elastic properties of the dense emulsion finally obtained and we demonstrate the presence of a finite yield stress. The approach reported can pave the way to a quantitative understanding of the complex interplay between the dynamics of mesoscale constituents and the large-scale flow properties of yield stress fluids.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"23 1","pages":"265 - 275"},"PeriodicalIF":1.9,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47195550","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 : 2021-10-15DOI: 10.1080/14685248.2021.1983180
N. Braun, R. Gore
A de-mix capable model for turbulence in compressible, variable density flows is proposed. The model is based on the Besnard-Harlow-Rauenzahn (BHR) family of models (Besnard D, Harlow F, Rauenzahn R, et al. Turbulence transport equations for variable-density turbulence and their relationship to two-field models. NM (United States): Los Alamos National Laboratory; 1992 (Technical Report LA-12303-MS), but is extended to track the evolution of the turbulent fluxes and fluctuations in the material mass fractions for each species present. The new evolution equations are introduced without requiring additional closures or new empirically tuned coefficients relative to previous BHR models, and are shown to improve the model’s ability to reproduce the behaviour of simulations containing mixing layers that are constrained by a stabilising force. The model is tested in a range of canonical flows including Rayleigh-Taylor driven, shock driven, and shear driven turbulence, and is shown to produce reasonable agreement with simulations and experiments in these scenarios.
提出了一种可压缩变密度流湍流的解混模型。该模型基于Besnard-Harlow-Rauenzahn (BHR)模型族(Besnard D, Harlow F, Rauenzahn R, et al.)。变密度湍流输运方程及其与双场模型的关系。NM(美国):洛斯阿拉莫斯国家实验室;1992年(技术报告LA-12303-MS)，但扩展到跟踪每个存在物种的湍流通量和物质质量分数波动的演变。新的演化方程的引入不需要额外的闭包或相对于以前的BHR模型的新的经验调整系数，并且被证明可以提高模型重现包含由稳定力约束的混合层的模拟行为的能力。该模型在一系列典型流动中进行了测试，包括瑞利-泰勒驱动、激波驱动和剪切驱动的湍流，结果表明，在这些情况下，该模型与模拟和实验结果相当吻合。
{"title":"A multispecies turbulence model for the mixing and de-mixing of miscible fluids","authors":"N. Braun, R. Gore","doi":"10.1080/14685248.2021.1983180","DOIUrl":"https://doi.org/10.1080/14685248.2021.1983180","url":null,"abstract":"A de-mix capable model for turbulence in compressible, variable density flows is proposed. The model is based on the Besnard-Harlow-Rauenzahn (BHR) family of models (Besnard D, Harlow F, Rauenzahn R, et al. Turbulence transport equations for variable-density turbulence and their relationship to two-field models. NM (United States): Los Alamos National Laboratory; 1992 (Technical Report LA-12303-MS), but is extended to track the evolution of the turbulent fluxes and fluctuations in the material mass fractions for each species present. The new evolution equations are introduced without requiring additional closures or new empirically tuned coefficients relative to previous BHR models, and are shown to improve the model’s ability to reproduce the behaviour of simulations containing mixing layers that are constrained by a stabilising force. The model is tested in a range of canonical flows including Rayleigh-Taylor driven, shock driven, and shear driven turbulence, and is shown to produce reasonable agreement with simulations and experiments in these scenarios.","PeriodicalId":49967,"journal":{"name":"Journal of Turbulence","volume":"22 1","pages":"784 - 813"},"PeriodicalIF":1.9,"publicationDate":"2021-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47807097","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 : 2021-10-03DOI: 10.1080/14685248.2021.1953698
I. Bulyzhenkov
ABSTRACT Monistic thermomechanics of eddy mater-space with metric stresses of Maxwellian type and inelastic metric waves can be developed for purely kinetic densities of the nonlocal mass-energy integral. Pseudo-Riemannian 4-geometry uses locally warped time to preserve the Euclidean sublight transport of nonlocally correlated densities with instantaneous metric connections and coherent conservation of local 4-currents everywhere. The kinematic viscosity of geometrised energy-momentum densities and their geodesic self-pushes by correlated metric stresses quantitatively clarify the adaptive all-unity of continuous kinetic energy, including material ether or variable rest-energy. The metric self-organisation of matter-space+time implies a nonlocal feedback of correlated eddy densities and their tensor response to the vector density of external forces. Such tensor inertial responses of correlated metric stresses reveal the nonlocal nature of turbulence and predict adaptive auto-modes or thermal waves of Euclidean material space due to the modified geodesic equation with viscose autowaves and the inverse Cavendish constant. The proposed nonlocal alternative to Euler/Navier-Stokes hydrodynamics can distinguish between Cartesian and Newtonian worldviews in conceptual laboratory probes of new macroscopic mechanics for metric self-organisations of thermokinetic energies of viscose material space without negative gravitational energies.
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