Pub Date : 2025-11-16DOI: 10.1016/j.compfluid.2025.106915
Lorenzo Botti , Daniele A. Di Pietro , Francesco Carlo Massa
We propose a Hybrid High-Order (HHO) formulation of the incompressible Navier–Stokes equations, that is well suited to be employed for the simulation of turbulent flows. The spatial discretization relies on hybrid velocity and pressure spaces and the temporal discretization is based on Explicit Singly Diagonal Implicit Runge-Kutta (ESDIRK) methods. The formulation possesses some attractive features that can be fruitfully exploited when high-fidelity computations are required, namely: pressure-robustness, conservation of volume enforced cell-by-cell up to machine precision, robustness in the inviscid limit, implicit high-order accurate time stepping with local time step adaptation, reduced memory footprint thanks to static condensation of both velocity and pressure, possibility to exploit inherited p-multilevel solution strategies to improve performance of iterative solvers. After demonstrating the relevant properties of the scheme in practice, performing challenging 2D and 3D test cases, we consider the simulation of the Taylor–Green Vortex flow problem at Reynolds 1 600.
{"title":"Hybrid High-order formulations with turbulence modelling capabilities for incompressible flow problems","authors":"Lorenzo Botti , Daniele A. Di Pietro , Francesco Carlo Massa","doi":"10.1016/j.compfluid.2025.106915","DOIUrl":"10.1016/j.compfluid.2025.106915","url":null,"abstract":"<div><div>We propose a Hybrid High-Order (HHO) formulation of the incompressible Navier–Stokes equations, that is well suited to be employed for the simulation of turbulent flows. The spatial discretization relies on hybrid velocity and pressure spaces and the temporal discretization is based on Explicit Singly Diagonal Implicit Runge-Kutta (ESDIRK) methods. The formulation possesses some attractive features that can be fruitfully exploited when high-fidelity computations are required, namely: pressure-robustness, conservation of volume enforced cell-by-cell up to machine precision, robustness in the inviscid limit, implicit high-order accurate time stepping with local time step adaptation, reduced memory footprint thanks to static condensation of both velocity and pressure, possibility to exploit inherited <em>p</em>-multilevel solution strategies to improve performance of iterative solvers. After demonstrating the relevant properties of the scheme in practice, performing challenging 2D and 3D test cases, we consider the simulation of the Taylor–Green Vortex flow problem at Reynolds 1 600.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106915"},"PeriodicalIF":3.0,"publicationDate":"2025-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615827","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 : 2025-11-15DOI: 10.1016/j.compfluid.2025.106911
T. Van Gastelen , W. Edeling , B. Sanderse
Reduced-order models (ROMs) are often used to accelerate the simulation of large physical systems. However, traditional ROM techniques, such as proper orthogonal decomposition (POD)-based methods, often struggle with advection-dominated flows due to the slow decay of singular values. This results in high computational costs and potential instabilities.
This paper proposes a novel approach using space-local POD to address the challenges arising from the slow singular value decay. Instead of global basis functions, our method employs local basis functions that are applied across the domain, analogous to the finite element method, but with a data-driven basis. By dividing the domain into subdomains and applying the space-local POD, we obtain a sparse representation that generalizes better outside the training regime. This allows the use of a larger number of basis functions compared to standard POD, without prohibitive computational costs. To ensure smoothness across subdomain boundaries, we introduce overlapping subdomains inspired by the partition of unity method.
Our approach is validated through simulations of the 1D and 2D advection equation. We demonstrate that using our space-local approach, we obtain a ROM that generalizes better to flow conditions not included in the training data. In addition, we show that the constructed ROM inherits the energy conservation and non-linear stability properties from the full-order model. Finally, we find that using a space-local ROM allows for larger time steps.
{"title":"Modeling advection-dominated flows with space-local reduced-order models","authors":"T. Van Gastelen , W. Edeling , B. Sanderse","doi":"10.1016/j.compfluid.2025.106911","DOIUrl":"10.1016/j.compfluid.2025.106911","url":null,"abstract":"<div><div>Reduced-order models (ROMs) are often used to accelerate the simulation of large physical systems. However, traditional ROM techniques, such as proper orthogonal decomposition (POD)-based methods, often struggle with advection-dominated flows due to the slow decay of singular values. This results in high computational costs and potential instabilities.</div><div>This paper proposes a novel approach using space-local POD to address the challenges arising from the slow singular value decay. Instead of global basis functions, our method employs local basis functions that are applied across the domain, analogous to the finite element method, but with a data-driven basis. By dividing the domain into subdomains and applying the space-local POD, we obtain a sparse representation that generalizes better outside the training regime. This allows the use of a larger number of basis functions compared to standard POD, without prohibitive computational costs. To ensure smoothness across subdomain boundaries, we introduce overlapping subdomains inspired by the partition of unity method.</div><div>Our approach is validated through simulations of the 1D and 2D advection equation. We demonstrate that using our space-local approach, we obtain a ROM that generalizes better to flow conditions not included in the training data. In addition, we show that the constructed ROM inherits the energy conservation and non-linear stability properties from the full-order model. Finally, we find that using a space-local ROM allows for larger time steps.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106911"},"PeriodicalIF":3.0,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615891","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 : 2025-11-15DOI: 10.1016/j.compfluid.2025.106917
Jian Shen , Xianliang Chen , Lin Fu
Accurate prediction of hypersonic turbulent boundary layers is critical for the design of hypersonic vehicles. Traditional turbulence models were originally developed for incompressible flows and are commonly extended to compressible conditions by employing density-weighted averages. In a recent study, Chen et al. (J. Fluid Mech., 2024, vol 987, A7) proposed an improved Baldwin-Lomax (BL) turbulence model by incorporating velocity transformations and the temperature-velocity relation. Their modifications yielded notable improvements for high-speed zero-pressure-gradient flat-plate flows. Building upon this foundation, the present study introduces further enhancements to Chen et al.’s BL model to improve its accuracy and robustness for complex hypersonic configurations. The improved BL turbulence model is implemented into a standard computational fluid dynamics (CFD) solver and validated against direct numerical simulation results and experimental data across two- and three-dimensional hypersonic cases involving pressure gradients, cold walls, and shock/boundary-layer interactions. The results show that the improved BL turbulence model generally achieves superior accuracy in attached flow regions compared to the baseline BL, Spalart-Allmaras and k–ω SST turbulence models. These findings highlight the model’s potential for practical use in hypersonic flow simulations, offering a valuable tool for aerospace engineering applications.
{"title":"Development and assessment of an improved Baldwin-Lomax turbulence model for complex hypersonic flows in two and three dimensions","authors":"Jian Shen , Xianliang Chen , Lin Fu","doi":"10.1016/j.compfluid.2025.106917","DOIUrl":"10.1016/j.compfluid.2025.106917","url":null,"abstract":"<div><div>Accurate prediction of hypersonic turbulent boundary layers is critical for the design of hypersonic vehicles. Traditional turbulence models were originally developed for incompressible flows and are commonly extended to compressible conditions by employing density-weighted averages. In a recent study, Chen et al. (J. Fluid Mech., 2024, vol 987, A7) proposed an improved Baldwin-Lomax (BL) turbulence model by incorporating velocity transformations and the temperature-velocity relation. Their modifications yielded notable improvements for high-speed zero-pressure-gradient flat-plate flows. Building upon this foundation, the present study introduces further enhancements to Chen et al.’s BL model to improve its accuracy and robustness for complex hypersonic configurations. The improved BL turbulence model is implemented into a standard computational fluid dynamics (CFD) solver and validated against direct numerical simulation results and experimental data across two- and three-dimensional hypersonic cases involving pressure gradients, cold walls, and shock/boundary-layer interactions. The results show that the improved BL turbulence model generally achieves superior accuracy in attached flow regions compared to the baseline BL, Spalart-Allmaras and k–<em>ω</em> SST turbulence models. These findings highlight the model’s potential for practical use in hypersonic flow simulations, offering a valuable tool for aerospace engineering applications.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106917"},"PeriodicalIF":3.0,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570082","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 : 2025-11-15DOI: 10.1016/j.compfluid.2025.106916
Francesco Mario D’Afiero
Accurate time integration of hyperbolic-parabolic systems, particularly in the presence of shocks and steep gradients, remains a central challenge in computational fluid dynamics. In this work, we propose a robust, adaptive time integration framework for discontinuous Galerkin discretizations that combines an embedded third-order Strong Stability Preserving Runge-Kutta method with physics-based shock capturing and novel error control strategies. The proposed method is based on total variation diminishing properties while leveraging a proportional-integral controller for adaptive step-size selection, eliminating the need for empirical CFL tuning. A key innovation lies in the introduction of an entropy-based filtering mechanism that modulates element-wise error estimates, effectively dampening spurious spikes induced by discontinuities. Additionally, the integral term of the PI controller is stabilized using a moving median over a sliding window, enhancing reliability in shock-dominated regimes. The overall methodology requires no parameter tuning beyond a user-defined error tolerance (as it is common in any ordinary differential equation) and is demonstrated to be stable and accurate across a broad range of canonical test cases. Compared to conventional CFL stable solution obtained for the same numerical setups in a previous work, the proposed approach consistently delivers improved accuracy and robustness for high-fidelity simulations in complex compressible flows.
{"title":"Embedded strong stability preserving Runge-Kutta methods with adaptive time stepping for shock-dominated flows","authors":"Francesco Mario D’Afiero","doi":"10.1016/j.compfluid.2025.106916","DOIUrl":"10.1016/j.compfluid.2025.106916","url":null,"abstract":"<div><div>Accurate time integration of hyperbolic-parabolic systems, particularly in the presence of shocks and steep gradients, remains a central challenge in computational fluid dynamics. In this work, we propose a robust, adaptive time integration framework for discontinuous Galerkin discretizations that combines an embedded third-order Strong Stability Preserving Runge-Kutta method with physics-based shock capturing and novel error control strategies. The proposed method is based on total variation diminishing properties while leveraging a proportional-integral controller for adaptive step-size selection, eliminating the need for empirical CFL tuning. A key innovation lies in the introduction of an entropy-based filtering mechanism that modulates element-wise error estimates, effectively dampening spurious spikes induced by discontinuities. Additionally, the integral term of the PI controller is stabilized using a moving median over a sliding window, enhancing reliability in shock-dominated regimes. The overall methodology requires no parameter tuning beyond a user-defined error tolerance (as it is common in any ordinary differential equation) and is demonstrated to be stable and accurate across a broad range of canonical test cases. Compared to conventional CFL stable solution obtained for the same numerical setups in a previous work, the proposed approach consistently delivers improved accuracy and robustness for high-fidelity simulations in complex compressible flows.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106916"},"PeriodicalIF":3.0,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615895","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 : 2025-11-13DOI: 10.1016/j.compfluid.2025.106899
Tyler Buchanan , Monica Lăcătuş , Alastair West , Richard P. Dwight
This study presents a novel approach for enhancing Reynolds-averaged Navier-Stokes (RANS) turbulence modeling through the application of a Relative Importance Term Analysis (RITA) methodology to develop a new zonally-augmented SST model. Traditional Linear Eddy Viscosity Models often struggle with separated flows. Our approach introduces a physics-based binary classifier that systematically identifies separated shear layers requiring correction by analyzing the relative magnitudes of terms in the turbulent kinetic energy equation. Using symbolic regression, we develop compact correction terms for Reynolds stress anisotropy and turbulent kinetic energy production. Trained on 2D configurations, our model demonstrates significant improvements in predicting separation dynamics while maintaining baseline performance in fully attached flows. Generalization tests on Ahmed body and Faith hill 3D configurations confirm robust transferability, establishing an effective methodology for targeted enhancement of RANS predictions in separated flows.
本研究提出了一种新的方法，通过应用相对重要项分析（RITA）方法来增强reynolds -average Navier-Stokes （RANS）湍流模型，从而建立一个新的纬向增强k−ω海表温度模型。传统的线性涡流黏度模型往往难以处理分离流。我们的方法引入了一个基于物理的二元分类器，通过分析湍流动能方程中项的相对大小，系统地识别需要校正的分离剪切层。利用符号回归，我们建立了雷诺应力各向异性和湍流动能产生的紧凑校正项。经过二维配置的训练，我们的模型在预测分离动力学方面有了显著的改进，同时在完全附着的流动中保持了基线性能。Ahmed body和Faith hill 3D配置的泛化测试证实了稳健的可转移性，为分离流中有针对性地增强RANS预测建立了有效的方法。
{"title":"Data-driven RANS closures using a relative importance term analysis based classifier for 2D and 3D separated flows","authors":"Tyler Buchanan , Monica Lăcătuş , Alastair West , Richard P. Dwight","doi":"10.1016/j.compfluid.2025.106899","DOIUrl":"10.1016/j.compfluid.2025.106899","url":null,"abstract":"<div><div>This study presents a novel approach for enhancing Reynolds-averaged Navier-Stokes (RANS) turbulence modeling through the application of a Relative Importance Term Analysis (RITA) methodology to develop a new zonally-augmented <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> SST model. Traditional Linear Eddy Viscosity Models often struggle with separated flows. Our approach introduces a physics-based binary classifier that systematically identifies separated shear layers requiring correction by analyzing the relative magnitudes of terms in the turbulent kinetic energy equation. Using symbolic regression, we develop compact correction terms for Reynolds stress anisotropy and turbulent kinetic energy production. Trained on 2D configurations, our model demonstrates significant improvements in predicting separation dynamics while maintaining baseline performance in fully attached flows. Generalization tests on Ahmed body and Faith hill 3D configurations confirm robust transferability, establishing an effective methodology for targeted enhancement of RANS predictions in separated flows.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106899"},"PeriodicalIF":3.0,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615894","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 : 2025-11-13DOI: 10.1016/j.compfluid.2025.106913
Haiming Zhu , Yuan Yang , Zunfeng Du , Jianxing Yu
This study presents an immersed boundary-lattice Boltzmann method (IB-LBM) simulation framework for vortex-induced vibration (VIV), implemented using the JAX framework to exploit GPU acceleration. The code is specifically structured to meet JAX’s functional and static requirements, incorporating an efficient multi-block grid refinement scheme and a novel dynamic region approach for immersed boundary calculations. Through systematic benchmarking and convergence studies, we revealed that the present dynamic region approach achieves improved efficiency by reducing computational workload while avoiding excessive dynamic array operations. We demonstrated that the grid refinement setting should be adjusted according to the Reynolds number to maintain accuracy. The results also showed that while grid refinement saves total time-to-solution, parallel efficiency is reduced due to the stalls caused by frequent inter-block communications. Furthermore, we compared fluid-structure coupling strategies, finding that while weak coupling is adequate for amplitude prediction, strong coupling with at least two iterations is necessary to eliminate spurious frequency artifacts in the response. These findings offer practical guidelines for achieving efficient and accurate VIV simulations with IB-LBM on modern GPU platforms.
{"title":"GPU accelerated vortex-induced vibration simulation using JAX: Efficiency and accuracy strategies","authors":"Haiming Zhu , Yuan Yang , Zunfeng Du , Jianxing Yu","doi":"10.1016/j.compfluid.2025.106913","DOIUrl":"10.1016/j.compfluid.2025.106913","url":null,"abstract":"<div><div>This study presents an immersed boundary-lattice Boltzmann method (IB-LBM) simulation framework for vortex-induced vibration (VIV), implemented using the JAX framework to exploit GPU acceleration. The code is specifically structured to meet JAX’s functional and static requirements, incorporating an efficient multi-block grid refinement scheme and a novel dynamic region approach for immersed boundary calculations. Through systematic benchmarking and convergence studies, we revealed that the present dynamic region approach achieves improved efficiency by reducing computational workload while avoiding excessive dynamic array operations. We demonstrated that the grid refinement setting should be adjusted according to the Reynolds number to maintain accuracy. The results also showed that while grid refinement saves total time-to-solution, parallel efficiency is reduced due to the stalls caused by frequent inter-block communications. Furthermore, we compared fluid-structure coupling strategies, finding that while weak coupling is adequate for amplitude prediction, strong coupling with at least two iterations is necessary to eliminate spurious frequency artifacts in the response. These findings offer practical guidelines for achieving efficient and accurate VIV simulations with IB-LBM on modern GPU platforms.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106913"},"PeriodicalIF":3.0,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570080","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 : 2025-11-12DOI: 10.1016/j.compfluid.2025.106893
Marica Pelanti
We describe liquid-vapor-gas flows by a hyperbolic single-velocity three-phase compressible flow model with instantaneous pressure relaxation that we studied in previous work. The model includes thermal relaxation terms to account for heat transfer, and chemical relaxation terms to describe mass transfer between the liquid and vapor phases. To numerically solve the model system we use a fractional step method where we alternate between the solution of the homogeneous system via finite volume HLLC-type schemes and the solution of systems of ordinary differential equations that take into account the relaxation source terms. In this work we propose a novel numerical procedure for chemical relaxation that can efficiently describe arbitrary-rate mass transfer, both slow finite-rate processes and stiff instantaneous ones. The main idea consists in describing the relaxation process by a system of ordinary differential equations that admits an analytical semi-exact exponential solution. This relaxation system is built by employing the relaxed models that can be derived analytically from the parent three-phase flow model in the limit of instantaneous mechanical and thermal relaxation processes, in order to guarantee the constraints of pressure and temperature equilibrium during phase transition. Some numerical experiments in one and two dimensions are presented to show the effectiveness of the proposed method.
{"title":"Numerical relaxation techniques for mass transfer in three-phase liquid-vapor-gas flows","authors":"Marica Pelanti","doi":"10.1016/j.compfluid.2025.106893","DOIUrl":"10.1016/j.compfluid.2025.106893","url":null,"abstract":"<div><div>We describe liquid-vapor-gas flows by a hyperbolic single-velocity three-phase compressible flow model with instantaneous pressure relaxation that we studied in previous work. The model includes thermal relaxation terms to account for heat transfer, and chemical relaxation terms to describe mass transfer between the liquid and vapor phases. To numerically solve the model system we use a fractional step method where we alternate between the solution of the homogeneous system via finite volume HLLC-type schemes and the solution of systems of ordinary differential equations that take into account the relaxation source terms. In this work we propose a novel numerical procedure for chemical relaxation that can efficiently describe arbitrary-rate mass transfer, both slow finite-rate processes and stiff instantaneous ones. The main idea consists in describing the relaxation process by a system of ordinary differential equations that admits an analytical semi-exact exponential solution. This relaxation system is built by employing the relaxed models that can be derived analytically from the parent three-phase flow model in the limit of instantaneous mechanical and thermal relaxation processes, in order to guarantee the constraints of pressure and temperature equilibrium during phase transition. Some numerical experiments in one and two dimensions are presented to show the effectiveness of the proposed method.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106893"},"PeriodicalIF":3.0,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570081","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 : 2025-11-11DOI: 10.1016/j.compfluid.2025.106912
Lubing Xu , Yanfei Li , Xiao Ma , Hengjie Guo , Shijin Shuai , Alexander Alekseevich Shevelev , Matvey Kraposhin
Pressure-based hybrid Kurganov-Noelle-Petrova (KNP) -PIMPLE algorithms have been widely used in all-Mach compressible flows to ensure the solution stability and maintaining physical consistency, but it suffers from high numerical diffusion at contact discontinuities and resulting in non-physical numerical oscillations at the two-phase regions, limiting the physical understanding of non-equilibrium phase change (flash boiling). In this work, a new hybrid solver named twoPhaseMixingHLLCFoam was proposed to avoid the drawbacks with three improvements: 1) Harten-Lax-van Leer-Contact (HLLC) scheme was used to replace the KNP scheme as a part of the hybrid framework to reduce the numerical diffusion; 2) The interpolation method of sound speed for Riemann solvers was modified to correctly reproduce the sound speed in two-phase buffer regions; 3) A new blending function based on local sound speed for identification of compressible and incompressible regimes was introduced.
The solver has been verified and validated against the analytical and experimental results. The improvement in numerical diffusion and the capability to resolve the pressure waves and shock waves propagation in gas-gas, gas-liquid and liquid-liquid flows were verified by a series of typical 1D cases. Then, the solver’s capability in resolving complex flow structures using 2D cases was demonstrated, especially in terms of the effectiveness of the transition between compressible and incompressible fluxes for all-Mach flows containing sub-, tran- and supersonic regimes simultaneously. Finally, a numerical study of acetone flash boiling jet has been conducted to demonstrate the solver’s capability of resolving under-expanded compressible two-phase jets with phase change. Scaling tests have shown that parallel performance of the new and original hybrid solvers is almost the same. Due to the adoption of a generalized mixture model, the new solver can be extended to multicomponent and even multiphase scenarios.
{"title":"A pressure-based hybrid framework for sub- and supersonic compressible two-phase flow with non-equilibrium phase change","authors":"Lubing Xu , Yanfei Li , Xiao Ma , Hengjie Guo , Shijin Shuai , Alexander Alekseevich Shevelev , Matvey Kraposhin","doi":"10.1016/j.compfluid.2025.106912","DOIUrl":"10.1016/j.compfluid.2025.106912","url":null,"abstract":"<div><div>Pressure-based hybrid Kurganov-Noelle-Petrova (KNP) -PIMPLE algorithms have been widely used in all-Mach compressible flows to ensure the solution stability and maintaining physical consistency, but it suffers from high numerical diffusion at contact discontinuities and resulting in non-physical numerical oscillations at the two-phase regions, limiting the physical understanding of non-equilibrium phase change (flash boiling). In this work, a new hybrid solver named <em>twoPhaseMixingHLLCFoam</em> was proposed to avoid the drawbacks with three improvements: 1) Harten-Lax-van Leer-Contact (HLLC) scheme was used to replace the KNP scheme as a part of the hybrid framework to reduce the numerical diffusion; 2) The interpolation method of sound speed for Riemann solvers was modified to correctly reproduce the sound speed in two-phase buffer regions; 3) A new blending function based on local sound speed for identification of compressible and incompressible regimes was introduced.</div><div>The solver has been verified and validated against the analytical and experimental results. The improvement in numerical diffusion and the capability to resolve the pressure waves and shock waves propagation in gas-gas, gas-liquid and liquid-liquid flows were verified by a series of typical 1D cases. Then, the solver’s capability in resolving complex flow structures using 2D cases was demonstrated, especially in terms of the effectiveness of the transition between compressible and incompressible fluxes for all-Mach flows containing sub-, tran- and supersonic regimes simultaneously. Finally, a numerical study of acetone flash boiling jet has been conducted to demonstrate the solver’s capability of resolving under-expanded compressible two-phase jets with phase change. Scaling tests have shown that parallel performance of the new and original hybrid solvers is almost the same. Due to the adoption of a generalized mixture model, the new solver can be extended to multicomponent and even multiphase scenarios.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106912"},"PeriodicalIF":3.0,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615892","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 : 2025-11-11DOI: 10.1016/j.compfluid.2025.106898
Anand Srinivasan , Perry Johnson , José Castillo
The control of aliasing errors arising from the non-linear convective terms in the incompressible Navier Stokes equation requires care when investigating turbulent flow regimes. Discretization schemes that fail to mirror the conservation properties such as global kinetic energy (which is inherent to the continuum form) can result in spurious numerical energy build-up for turbulent flow simulations. Mimetic difference methods that operate on a staggered grid satisfy a discrete version of the continuum conservation laws, thereby resulting in more accurate numerical simulations. The high order mimetic operators of Corbino-Castillo using a skew-symmetric formulation is considered in the present work. On the temporal side, pseudo symplectic methods are investigated to obtain global kinetic energy preserving numerical solutions of the NS equations in turbulent flow regimes. Numerical examples highlighting the implementation of the mimetic pseudo symplectic schemes are also presented.
{"title":"Mimetic differences and pseudo symplectic Runge Kutta methods for incompressible Navier Stokes equations","authors":"Anand Srinivasan , Perry Johnson , José Castillo","doi":"10.1016/j.compfluid.2025.106898","DOIUrl":"10.1016/j.compfluid.2025.106898","url":null,"abstract":"<div><div>The control of aliasing errors arising from the non-linear convective terms in the incompressible Navier Stokes equation requires care when investigating turbulent flow regimes. Discretization schemes that fail to mirror the conservation properties such as global kinetic energy (which is inherent to the continuum form) can result in spurious numerical energy build-up for turbulent flow simulations. Mimetic difference methods that operate on a staggered grid satisfy a discrete version of the continuum conservation laws, thereby resulting in more accurate numerical simulations. The high order mimetic operators of Corbino-Castillo using a skew-symmetric formulation is considered in the present work. On the temporal side, pseudo symplectic methods are investigated to obtain global kinetic energy preserving numerical solutions of the NS equations in turbulent flow regimes. Numerical examples highlighting the implementation of the mimetic pseudo symplectic schemes are also presented.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"305 ","pages":"Article 106898"},"PeriodicalIF":3.0,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570123","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 : 2025-11-11DOI: 10.1016/j.compfluid.2025.106914
Yimeng Du , Zhendong Jin , Chengjun Zhang , Yan Cui , Yulong Wang , Rongxuan Hu , Peng Gao , Martin Sommerfeld
This work introduces a novel one-way coupled Lagrangian Particle Tracking (LPT) approach that demonstrates strong compatibility with various fluid solvers, enabling efficient particle tracking in unsteady flows. By utilizing the standard Visualization Toolkit (VTK) format, this method efficiently manages data by loading sampled instantaneous flow data, significantly reducing computational costs while tracking multiple particle properties. Crucially, this decoupling from fluid solvers allows researchers to rapidly prototype and validate new LPT models without rerunning the underlying CFD simulations, thereby dramatically accelerating iterative model development. Consequently, the method requires that the time interval be sufficiently fine to capture key flow characteristics, while the total time span covers the complete evolutionary process of the flow. Extensive numerical validations confirm its accuracy and versatility across diverse flow scenarios, including Couette and Poiseuille flows, lid-driven cavity flow, backward-facing step flow, and 90° duct bend flow. Its effectiveness in pharmaceutical aerosol applications—encompassing respiratory and dry-powder inhalers—further highlights its scalability and physical fidelity. The approach's flexibility supports the integration of complex physical models and offers a user-friendly interface through the open-source software ParaView®. This innovation not only addresses challenges faced by engineers using commercial Computational Fluid Dynamics (CFD) software but also transforms the research workflow by enabling agile exploration of particle physics, thus expediting discovery timelines in multiphase flow studies.
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