Pub Date : 2025-10-18DOI: 10.1016/j.compfluid.2025.106879
Jiali Tu , Haijian Yang , Shanlin Qin , Weifeng Guo , Rongliang Chen
Aortic dissection is a serious clinical condition characterized by a tear in the intima of the aortic wall. To better understand and treat this complex condition, researchers increasingly use hemodynamic simulations based on fluid-structure interaction (FSI). However, time-dependent three-dimensional FSI simulations in aortic dissection are complex and often inefficient in terms of computational time and memory. In this paper, we present a highly scalable parallel numerical method to simulate the blood flow in a full-sized aorta with dissection. The blood flow is modeled using the unsteady incompressible Navier-Stokes equations in an arbitrary Lagrangian-Eulerian framework, and the aortic wall is modeled as linear elastic material in a Lagrangian description. The entire system is discretized monolithically by a stabilized finite element method in space and a fully implicit scheme in time, and the resulting algebraic system is then solved using the Newton-Krylov-Schwarz method. Hemodynamic parameters within the aortic dissection are examined, revealing differences from simulations that rely solely on computational fluid dynamics. Scalability tests on a supercomputer demonstrate a parallel efficiency of 44.1 % with up to 2304 processor cores, reducing the simulation time for an entire cardiac cycle to 0.36 h.
{"title":"A highly scalable parallel simulation of blood flow with fluid-structure interaction in patient-specific aortic dissection","authors":"Jiali Tu , Haijian Yang , Shanlin Qin , Weifeng Guo , Rongliang Chen","doi":"10.1016/j.compfluid.2025.106879","DOIUrl":"10.1016/j.compfluid.2025.106879","url":null,"abstract":"<div><div>Aortic dissection is a serious clinical condition characterized by a tear in the intima of the aortic wall. To better understand and treat this complex condition, researchers increasingly use hemodynamic simulations based on fluid-structure interaction (FSI). However, time-dependent three-dimensional FSI simulations in aortic dissection are complex and often inefficient in terms of computational time and memory. In this paper, we present a highly scalable parallel numerical method to simulate the blood flow in a full-sized aorta with dissection. The blood flow is modeled using the unsteady incompressible Navier-Stokes equations in an arbitrary Lagrangian-Eulerian framework, and the aortic wall is modeled as linear elastic material in a Lagrangian description. The entire system is discretized monolithically by a stabilized finite element method in space and a fully implicit scheme in time, and the resulting algebraic system is then solved using the Newton-Krylov-Schwarz method. Hemodynamic parameters within the aortic dissection are examined, revealing differences from simulations that rely solely on computational fluid dynamics. Scalability tests on a supercomputer demonstrate a parallel efficiency of 44.1 % with up to 2304 processor cores, reducing the simulation time for an entire cardiac cycle to 0.36 h.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106879"},"PeriodicalIF":3.0,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145359266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-17DOI: 10.1016/j.compfluid.2025.106869
Gino I. Montecinos , Eleuterio F. Toro
The WENO-DK reconstruction [M. Dumbser and M. Käser, JCOMP.221:693-723, (2007)] is a type of WENO procedure in which, for the one-dimensional case only the leftmost, centered and rightmost stencils are involved. For even orders the central stencil contains more elements than degrees of freedom and an overdetermined system is solved by means of a least-squares approach. Here, it is numerically investigated the impact of choosing the smallest and largest central stencil around the cell of interests and proposed two variants to obtain the central polynomial where the solution of overdetermined systems is not needed. Implementations of the proposed approaches in the framework of fully discrete ADER schemes for the linear advection equation and the Euler equations of gas dynamics are reported. Comparisons with conventional WENO and conventional WENO-DK confirm that the proposed variants of WENO-DK are a suitable compromise between simplicity and accuracy in the context of ADER schemes, implemented up to the tenth order of accuracy in space and time.
{"title":"Variants for the WENO-DK reconstruction of even orders in the framework of ADER methods for very high orders of accuracy","authors":"Gino I. Montecinos , Eleuterio F. Toro","doi":"10.1016/j.compfluid.2025.106869","DOIUrl":"10.1016/j.compfluid.2025.106869","url":null,"abstract":"<div><div>The WENO-DK reconstruction [M. Dumbser and M. Käser, <em>JCOMP.</em> <strong>221</strong>:693-723, (2007)] is a type of WENO procedure in which, for the one-dimensional case only the leftmost, centered and rightmost stencils are involved. For even orders the central stencil contains more elements than degrees of freedom and an overdetermined system is solved by means of a least-squares approach. Here, it is numerically investigated the impact of choosing the smallest and largest central stencil around the cell of interests and proposed two variants to obtain the central polynomial where the solution of overdetermined systems is not needed. Implementations of the proposed approaches in the framework of fully discrete ADER schemes for the linear advection equation and the Euler equations of gas dynamics are reported. Comparisons with conventional WENO and conventional WENO-DK confirm that the proposed variants of WENO-DK are a suitable compromise between simplicity and accuracy in the context of ADER schemes, implemented up to the tenth order of accuracy in space and time.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106869"},"PeriodicalIF":3.0,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145325680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-17DOI: 10.1016/j.compfluid.2025.106881
A.R. Kocharina , D.V. Chirkov
The incompressible Navier-Stokes equations are solved using the finite-volume artificial compressibility method. A Godunov-type scheme with an exact Riemann solver is developed for the evaluation of inviscid fluxes across cell faces. To this end, the exact solution of the one-dimensional Riemann problem for the artificial compressibility equations is obtained using the method of -diagrams. The uniqueness of the solution is rigorously proven. The method is then extended to the multidimensional case. Two approaches for evaluation of the tangential velocity component are examined and discussed. A high-order variant of the Godunov scheme based on third-order MUSCL interpolation is proposed. At that, non-uniformity of the grid is taken into account. An implicit formulation of the scheme is developed, and the linearization process is described in detail. The proposed scheme is compared with the well-established Roe scheme through a series of steady-state two-dimensional benchmark problems, including inviscid and viscous flows around a circular cylinder and the 2D lid-driven cavity flow. The performance of the schemes on non-orthogonal grids is also investigated. Finally, both Roe and Godunov schemes are applied to the simulation of a three-dimensional turbulent flow in a hydraulic turbine flow passage. The results show that while both schemes exhibit comparable accuracy and convergence, the Godunov scheme offers advantages for inviscid simulations on highly non-orthogonal grids.
{"title":"Godunov scheme for numerical solution of incompressible Navier-Stokes equations","authors":"A.R. Kocharina , D.V. Chirkov","doi":"10.1016/j.compfluid.2025.106881","DOIUrl":"10.1016/j.compfluid.2025.106881","url":null,"abstract":"<div><div>The incompressible Navier-Stokes equations are solved using the finite-volume artificial compressibility method. A Godunov-type scheme with an exact Riemann solver is developed for the evaluation of inviscid fluxes across cell faces. To this end, the exact solution of the one-dimensional Riemann problem for the artificial compressibility equations is obtained using the method of <span><math><mrow><mo>(</mo><mi>u</mi><mo>,</mo><mi>p</mi><mo>)</mo></mrow></math></span>-diagrams. The uniqueness of the solution is rigorously proven. The method is then extended to the multidimensional case. Two approaches for evaluation of the tangential velocity component are examined and discussed. A high-order variant of the Godunov scheme based on third-order MUSCL interpolation is proposed. At that, non-uniformity of the grid is taken into account. An implicit formulation of the scheme is developed, and the linearization process is described in detail. The proposed scheme is compared with the well-established Roe scheme through a series of steady-state two-dimensional benchmark problems, including inviscid and viscous flows around a circular cylinder and the 2D lid-driven cavity flow. The performance of the schemes on non-orthogonal grids is also investigated. Finally, both Roe and Godunov schemes are applied to the simulation of a three-dimensional turbulent flow in a hydraulic turbine flow passage. The results show that while both schemes exhibit comparable accuracy and convergence, the Godunov scheme offers advantages for inviscid simulations on highly non-orthogonal grids.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"304 ","pages":"Article 106881"},"PeriodicalIF":3.0,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-16DOI: 10.1016/j.compfluid.2025.106878
A.A. Gavrilov , A.V. Shebelev , A.V. Minakov
The paper presents the results of testing of a Eulerian model of two-phase turbulent non-Newtonian flow with coarse particles, proposed by the authors. The model includes equations for two-phase flow with rheological correlations and an equation for particle concentration transfer taking into account interfacial slip. The turbulence model takes into account the modulation of turbulence by particles. The proposed model has been validated on the problems of steady turbulent flow of shear thinning viscoplastic fluid with heavy particles in a horizontal pipe. The impact of Reynolds number and rheological parameters on the reliability of numerical simulations was examined. A comparison of experimental data with DNS-DEM simulation data has demonstrated that the proposed model is capable of accurately predicting the distribution of particle concentration, particle velocity, as well as carrier flow and pressure drop in the channel.
{"title":"Statistical model of turbulent flow of shear-thinning viscoplastic fluid with solid particles","authors":"A.A. Gavrilov , A.V. Shebelev , A.V. Minakov","doi":"10.1016/j.compfluid.2025.106878","DOIUrl":"10.1016/j.compfluid.2025.106878","url":null,"abstract":"<div><div>The paper presents the results of testing of a Eulerian model of two-phase turbulent non-Newtonian flow with coarse particles, proposed by the authors. The model includes equations for two-phase flow with rheological correlations and an equation for particle concentration transfer taking into account interfacial slip. The turbulence model takes into account the modulation of turbulence by particles. The proposed model has been validated on the problems of steady turbulent flow of shear thinning viscoplastic fluid with heavy particles in a horizontal pipe. The impact of Reynolds number and rheological parameters on the reliability of numerical simulations was examined. A comparison of experimental data with DNS-DEM simulation data has demonstrated that the proposed model is capable of accurately predicting the distribution of particle concentration, particle velocity, as well as carrier flow and pressure drop in the channel.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"304 ","pages":"Article 106878"},"PeriodicalIF":3.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-16DOI: 10.1016/j.compfluid.2025.106874
Anna Schwarz , Daniel Kempf , Jens Keim , Patrick Kopper , Christian Rohde , Andrea Beck
High-order methods are well-suited for the numerical simulation of complex compressible turbulent flows, but require additional stabilization techniques to capture instabilities arising from the underlying non-linear hyperbolic equations. This paper provides a detailed comparison of the effectiveness of entropy stable discontinuous Galerkin methods for the stabilization of compressible (wall-bounded) turbulent flows. For this investigation, an entropy stable discontinuous Galerkin spectral element method is applied on Gauss–Legendre and Gauss–Lobatto nodes. In the compressible regime, an additional stabilization technique for shock capturing based on a convex blending of a low-order finite volume with the high-order discontinuous Galerkin operator is utilized. The present investigation provides a systematic study from convergence tests, to the Taylor–Green vortex and finally to a more intricate turbulent wall-bounded 3D diffuser flow, encompassing both weakly compressible and compressible regimes. The comparison demonstrates that the DGSEM on Gauss–Lobatto nodes is generally less accurate for an equal amount of degrees of freedom. Conversely, it is faster than the DGSEM on Gauss–Legendre nodes due to a less severe time step restriction and simpler numerical operator. A performance comparison reveals that the DGSEM on Gauss–Lobatto nodes generally outperforms the DGSEM on Gauss nodes for under-resolved turbulence in the subsonic regime on a periodic domain. Conversely, the opposite effect can be observed for wall-bounded flows as well as the supersonic regime, the latter depending of course on the chosen shock-capturing scheme. To the author’s knowledge, this is the first time for which a comparison of entropy stable DGSEM on Gauss–Lobatto and Gauss–Legendre has been performed for compressible, wall-bounded turbulent flows with separation.
{"title":"Comparison of entropy stable collocation high-order DG methods for compressible turbulent flows","authors":"Anna Schwarz , Daniel Kempf , Jens Keim , Patrick Kopper , Christian Rohde , Andrea Beck","doi":"10.1016/j.compfluid.2025.106874","DOIUrl":"10.1016/j.compfluid.2025.106874","url":null,"abstract":"<div><div>High-order methods are well-suited for the numerical simulation of complex compressible turbulent flows, but require additional stabilization techniques to capture instabilities arising from the underlying non-linear hyperbolic equations. This paper provides a detailed comparison of the effectiveness of entropy stable discontinuous Galerkin methods for the stabilization of compressible (wall-bounded) turbulent flows. For this investigation, an entropy stable discontinuous Galerkin spectral element method is applied on Gauss–Legendre and Gauss–Lobatto nodes. In the compressible regime, an additional stabilization technique for shock capturing based on a convex blending of a low-order finite volume with the high-order discontinuous Galerkin operator is utilized. The present investigation provides a systematic study from convergence tests, to the Taylor–Green vortex and finally to a more intricate turbulent wall-bounded 3D diffuser flow, encompassing both weakly compressible and compressible regimes. The comparison demonstrates that the DGSEM on Gauss–Lobatto nodes is generally less accurate for an equal amount of degrees of freedom. Conversely, it is faster than the DGSEM on Gauss–Legendre nodes due to a less severe time step restriction and simpler numerical operator. A performance comparison reveals that the DGSEM on Gauss–Lobatto nodes generally outperforms the DGSEM on Gauss nodes for under-resolved turbulence in the subsonic regime on a periodic domain. Conversely, the opposite effect can be observed for wall-bounded flows as well as the supersonic regime, the latter depending of course on the chosen shock-capturing scheme. To the author’s knowledge, this is the first time for which a comparison of entropy stable DGSEM on Gauss–Lobatto and Gauss–Legendre has been performed for compressible, wall-bounded turbulent flows with separation.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106874"},"PeriodicalIF":3.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145359265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-13DOI: 10.1016/j.compfluid.2025.106873
Hiroyuki Asada, Kanako Maruyama, Soshi Kawai
Low-pass filters designed on unstructured grids are investigated in terms of a transfer function in the wavenumber space. The transfer functions on unstructured grids are derived, and the properties of the low-pass filters for removing high-wavenumber components and inducing phase errors are investigated through the derived transfer functions. The transfer function reveals that the low-pass filters on unstructured grids can achieve the property that higher-wavenumber components are removed more by adjusting a filter coefficient to a small value, whereas large filter coefficients induce unfavorable amplifications of high-wavenumber components. The presence of phase errors induced by the low-pass filters on triangle unstructured cells is also found by the transfer function. Furthermore, the transfer function shows that the numerical methods for evaluating the gradients that appear in the filter formulation affect the characteristics of the low-pass filters and that the simplest central scheme can have an advantage in terms of retaining numerical robustness by removing high-wavenumber components compared to the edge-normal augmentation scheme. The numerical experiments of inviscid Taylor–Green vortex and shock-vortex interaction are also conducted with the low-pass filter coupled with the non-dissipative kinetic energy and entropy preserving (KEEP) scheme on unstructured grids, demonstrating the validity of the present transfer function of the low-pass filter.
{"title":"Transfer function of low-pass filters on unstructured grids","authors":"Hiroyuki Asada, Kanako Maruyama, Soshi Kawai","doi":"10.1016/j.compfluid.2025.106873","DOIUrl":"10.1016/j.compfluid.2025.106873","url":null,"abstract":"<div><div>Low-pass filters designed on unstructured grids are investigated in terms of a transfer function in the wavenumber space. The transfer functions on unstructured grids are derived, and the properties of the low-pass filters for removing high-wavenumber components and inducing phase errors are investigated through the derived transfer functions. The transfer function reveals that the low-pass filters on unstructured grids can achieve the property that higher-wavenumber components are removed more by adjusting a filter coefficient to a small value, whereas large filter coefficients induce unfavorable amplifications of high-wavenumber components. The presence of phase errors induced by the low-pass filters on triangle unstructured cells is also found by the transfer function. Furthermore, the transfer function shows that the numerical methods for evaluating the gradients that appear in the filter formulation affect the characteristics of the low-pass filters and that the simplest central scheme can have an advantage in terms of retaining numerical robustness by removing high-wavenumber components compared to the edge-normal augmentation scheme. The numerical experiments of inviscid Taylor–Green vortex and shock-vortex interaction are also conducted with the low-pass filter coupled with the non-dissipative kinetic energy and entropy preserving (KEEP) scheme on unstructured grids, demonstrating the validity of the present transfer function of the low-pass filter.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106873"},"PeriodicalIF":3.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145325679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-13DOI: 10.1016/j.compfluid.2025.106876
Layal Jbara , Aashish Goyal , Anthony Wachs
<div><div>We introduce a deep neural network framework that combines machine learning with domain knowledge to model particle–laden flows, specifically focusing on suspensions of non-spherical polyhedral particles. Building upon our flow configuration knowledge, our model leverages Graph Neural networks (GNNs) to capture the intricate spatial, geometrical and relational interactions between particles. The particles are represented as nodes in a directed graph, with pairwise interactions encoded as directed edges, capturing both the local microstructure and inherent symmetries of the flow configuration. A multi-layer perceptron (MLP) function is employed for message passing, and a multi-headed attention mechanism is integrated to weigh the importance of neighboring nodes and edge features in the aggregation process. We define the directed edges between the nodes using the incidence function <span><math><msub><mrow><mi>ψ</mi></mrow><mrow><mi>G</mi></mrow></msub></math></span> such that the <span><math><mi>k</mi></math></span>th nearest neighbors of each particle <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> are identified using the neighborhood defined by <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>k</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> and we test different values of <span><math><mi>k</mi></math></span> to assess the impact of varying the number of neighbors. The convergence of predictions improves with an increasing number of neighbors (<span><math><mi>k</mi></math></span>), highlighting the importance of refining the neighborhood structure for better model performance. Our results demonstrate the effectiveness of the GNN in predicting streamwise drag forces, with <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> values consistently exceeding 0.90 for <span><math><mrow><mi>Δ</mi><msub><mrow><mi>F</mi></mrow><mrow><mi>x</mi></mrow></msub></mrow></math></span>, and exceeding 0.80 for transverse lift force<span><math><mrow><mi>Δ</mi><msub><mrow><mi>F</mi></mrow><mrow><mi>y</mi></mrow></msub></mrow></math></span> and torque <span><math><mrow><mi>Δ</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>z</mi></mrow></msub></mrow></math></span> at all <span><math><mi>κ</mi></math></span> values for low <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> and <span><math><mi>ϕ</mi></math></span>. However, the model’s performance decreases as <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> and <span><math><mi>ϕ</mi></math></span> increase, particularly for transverse forces and torques. We show that the GNN outperforms the literature-reported models that lack incorporation of local physical properties as input parameters and provides comparable or superior performance to Convolutional Neural Networks (CNNs), even when local velocity is included. The GNN excels in cap
{"title":"Graph neural network based model of hydrodynamic closure laws in non-spherical particle–laden flows","authors":"Layal Jbara , Aashish Goyal , Anthony Wachs","doi":"10.1016/j.compfluid.2025.106876","DOIUrl":"10.1016/j.compfluid.2025.106876","url":null,"abstract":"<div><div>We introduce a deep neural network framework that combines machine learning with domain knowledge to model particle–laden flows, specifically focusing on suspensions of non-spherical polyhedral particles. Building upon our flow configuration knowledge, our model leverages Graph Neural networks (GNNs) to capture the intricate spatial, geometrical and relational interactions between particles. The particles are represented as nodes in a directed graph, with pairwise interactions encoded as directed edges, capturing both the local microstructure and inherent symmetries of the flow configuration. A multi-layer perceptron (MLP) function is employed for message passing, and a multi-headed attention mechanism is integrated to weigh the importance of neighboring nodes and edge features in the aggregation process. We define the directed edges between the nodes using the incidence function <span><math><msub><mrow><mi>ψ</mi></mrow><mrow><mi>G</mi></mrow></msub></math></span> such that the <span><math><mi>k</mi></math></span>th nearest neighbors of each particle <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> are identified using the neighborhood defined by <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>k</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> and we test different values of <span><math><mi>k</mi></math></span> to assess the impact of varying the number of neighbors. The convergence of predictions improves with an increasing number of neighbors (<span><math><mi>k</mi></math></span>), highlighting the importance of refining the neighborhood structure for better model performance. Our results demonstrate the effectiveness of the GNN in predicting streamwise drag forces, with <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> values consistently exceeding 0.90 for <span><math><mrow><mi>Δ</mi><msub><mrow><mi>F</mi></mrow><mrow><mi>x</mi></mrow></msub></mrow></math></span>, and exceeding 0.80 for transverse lift force<span><math><mrow><mi>Δ</mi><msub><mrow><mi>F</mi></mrow><mrow><mi>y</mi></mrow></msub></mrow></math></span> and torque <span><math><mrow><mi>Δ</mi><msub><mrow><mi>T</mi></mrow><mrow><mi>z</mi></mrow></msub></mrow></math></span> at all <span><math><mi>κ</mi></math></span> values for low <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> and <span><math><mi>ϕ</mi></math></span>. However, the model’s performance decreases as <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> and <span><math><mi>ϕ</mi></math></span> increase, particularly for transverse forces and torques. We show that the GNN outperforms the literature-reported models that lack incorporation of local physical properties as input parameters and provides comparable or superior performance to Convolutional Neural Networks (CNNs), even when local velocity is included. The GNN excels in cap","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106876"},"PeriodicalIF":3.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145325683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-13DOI: 10.1016/j.compfluid.2025.106875
Giulio Gori
We propose to rely on a flat Dirichlet distribution to sample the eigenvalues of the Reynolds Stress Tensor in RANS simulations. The goal is to forward propagate the uncertainty inherent the structure of the turbulence closure to targeted QoIs. The flat Dirichlet distribution is defined over the 2-dimensional simplex delimiting the Reynolds Stress Tensor realizability conditions. This ensures the tensor positive-definiteness and serves the uncertainty forward propagation by means of diverse techniques e.g., Monte Carlo or Polynomial Chaos Expansions. Simulations are performed using a modified version of the open-source SU2 suite. Results are obtained for two reference test cases. Namely, the subsonic air flow over a backward facing step and the NACA0012 airfoil operating in subsonic conditions and with a variable angle of attack.
{"title":"Turbulence model uncertainty estimation via Monte Carlo perturbation of the Reynolds Stress Tensor","authors":"Giulio Gori","doi":"10.1016/j.compfluid.2025.106875","DOIUrl":"10.1016/j.compfluid.2025.106875","url":null,"abstract":"<div><div>We propose to rely on a flat Dirichlet distribution to sample the eigenvalues of the Reynolds Stress Tensor in RANS simulations. The goal is to forward propagate the uncertainty inherent the structure of the turbulence closure to targeted QoIs. The flat Dirichlet distribution is defined over the 2-dimensional simplex delimiting the Reynolds Stress Tensor realizability conditions. This ensures the tensor positive-definiteness and serves the uncertainty forward propagation by means of diverse techniques e.g., Monte Carlo or Polynomial Chaos Expansions. Simulations are performed using a modified version of the open-source SU2 suite. Results are obtained for two reference test cases. Namely, the subsonic air flow over a backward facing step and the NACA0012 airfoil operating in subsonic conditions and with a variable angle of attack.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106875"},"PeriodicalIF":3.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145325678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The central-upwind weighted essentially non-oscillatory (WENO) scheme introduces the downwind substencil to reconstruct the numerical flux, where the smoothness indicator for the downwind substencil is of critical importance in maintaining high order in smooth regions and preserving the essentially non-oscillatory behavior in shock capturing. In this study, we design the smoothness indicator for the downwind substencil by simply summing up all local smoothness indicators and taking the average, which includes the regularity information of the whole stencil. Accordingly the JS-type and Z-type nonlinear weights, based on simple local smoothness indicators, are developed for the fourth-order central-upwind WENO scheme. The accuracy, robustness, and high-resolution properties of our proposed schemes are demonstrated in a variety of one- and two-dimensional problems.
{"title":"JS-type and Z-type weights for fourth-order central-upwind weighted essentially non-oscillatory schemes","authors":"Jiaxi Gu , Xinjuan Chen , Kwanghyuk Park , Jae-Hun Jung","doi":"10.1016/j.compfluid.2025.106867","DOIUrl":"10.1016/j.compfluid.2025.106867","url":null,"abstract":"<div><div>The central-upwind weighted essentially non-oscillatory (WENO) scheme introduces the downwind substencil to reconstruct the numerical flux, where the smoothness indicator for the downwind substencil is of critical importance in maintaining high order in smooth regions and preserving the essentially non-oscillatory behavior in shock capturing. In this study, we design the smoothness indicator for the downwind substencil by simply summing up all local smoothness indicators and taking the average, which includes the regularity information of the whole stencil. Accordingly the JS-type and Z-type nonlinear weights, based on simple local smoothness indicators, are developed for the fourth-order central-upwind WENO scheme. The accuracy, robustness, and high-resolution properties of our proposed schemes are demonstrated in a variety of one- and two-dimensional problems.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106867"},"PeriodicalIF":3.0,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145325685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-10-09DOI: 10.1016/j.compfluid.2025.106858
Amareshwara Sainadh Chamarthi
The paper proposes a physically consistent numerical discretization approach for simulating viscous compressible multicomponent flows. It has two main contributions. First, a contact discontinuity (and material interface) detector is developed. In those regions of contact discontinuities, the THINC (Tangent of Hyperbola for INterface Capturing) approach is used for reconstructing appropriate variables (phasic densities). For other flow regions, the variables are reconstructed using the Monotonicity-preserving (MP) scheme (or Weighted essentially non-oscillatory scheme (WENO)). For reconstruction in the characteristic space, the THINC approach is used only for the contact (or entropy) wave and volume fractions. For the reconstruction of primitive variables, the THINC approach is used for phasic densities and volume fractions only, offering an effective solution for reducing dissipation errors near contact discontinuities. The numerical results of the benchmark tests show that the proposed method captured the material interface sharply compared to existing methods. The second contribution is the development of an algorithm that uses a central reconstruction scheme for the tangential velocities, as they are continuous across material interfaces in viscous flows. In this regard, the Ducros sensor (a shock detector that cannot detect material interfaces) is employed to compute the tangential velocities using a central scheme across material interfaces. Using the central scheme does not produce any oscillations at the material interface. The proposed approach is thoroughly validated with several benchmark test cases for compressible multicomponent flows, highlighting its advantages. The physics appropriate approach also shown to prevent spurious vortices, despite being formally second-order accurate for nonlinear problems, on a coarser mesh than a genuinely high-order accurate method.
{"title":"Physics appropriate interface capturing reconstruction approach for viscous compressible multicomponent flows","authors":"Amareshwara Sainadh Chamarthi","doi":"10.1016/j.compfluid.2025.106858","DOIUrl":"10.1016/j.compfluid.2025.106858","url":null,"abstract":"<div><div>The paper proposes a physically consistent numerical discretization approach for simulating viscous compressible multicomponent flows. It has two main contributions. First, a contact discontinuity (and material interface) detector is developed. In those regions of contact discontinuities, the THINC (Tangent of Hyperbola for INterface Capturing) approach is used for reconstructing appropriate variables (phasic densities). For other flow regions, the variables are reconstructed using the Monotonicity-preserving (MP) scheme (or Weighted essentially non-oscillatory scheme (WENO)). For reconstruction in the characteristic space, the THINC approach is used only for the contact (or entropy) wave and volume fractions. For the reconstruction of primitive variables, the THINC approach is used for phasic densities and volume fractions only, offering an effective solution for reducing dissipation errors near contact discontinuities. The numerical results of the benchmark tests show that the proposed method captured the material interface sharply compared to existing methods. The second contribution is the development of an algorithm that uses a central reconstruction scheme for the tangential velocities, as they are continuous across material interfaces in viscous flows. In this regard, the Ducros sensor (a shock detector that cannot detect material interfaces) is employed to compute the tangential velocities using a central scheme across material interfaces. Using the central scheme does not produce any oscillations at the material interface. The proposed approach is thoroughly validated with several benchmark test cases for compressible multicomponent flows, highlighting its advantages. The physics appropriate approach also shown to prevent spurious vortices, despite being formally second-order accurate for nonlinear problems, on a coarser mesh than a genuinely high-order accurate method.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"303 ","pages":"Article 106858"},"PeriodicalIF":3.0,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145264410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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