Computers & Fluids最新文献

{"title":"Direct Discontinuous Galerkin methods for the reacting multi-component flow equations","authors":"G. Absillis ,&nbsp;H. Luo ,&nbsp;P. Greene ,&nbsp;R. Nourgaliev ,&nbsp;M. Goodson","doi":"10.1016/j.compfluid.2025.106774","DOIUrl":"10.1016/j.compfluid.2025.106774","url":null,"abstract":"<div><div>The Direct Discontinuous Galerkin (DDG (Liu and Yan, 2008)) method and a counterpart with Interface Correction (DDGIC (Danis and Yan, 2022)) are extended to compute diffusion terms that arise when solving the compressible multi-component flow equations in thermochemical nonequilibrium. Thermodynamic properties, transport properties, chemical reaction rates, and energy exchange terms are computed using Mutation++ (Scoggins et al., 2020). The DG method is applied on unstructured grids, where the accuracy and convergence rates can be sensitive to the numerical method chosen for parabolic terms. A method for determining the homogeneity tensor of the flow equations required for DDGIC is shown. The convergence properties of the DDG methods are studied and compared to the Interior Penalty (IP) method. A number of numerical experiments are conducted to assess the accuracy and performance of the method. The numerical results and convergence studies indicate that DDG and DDGIC provide accurate solutions and perform well for general flows in thermochemical nonequilibrium.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106774"},"PeriodicalIF":3.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144863888","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}

{"title":"A positive-preserving unified gas-kinetic scheme for radiative transfer equations in cylindrical coordinates","authors":"Yi Wang ,&nbsp;Shuang Tan ,&nbsp;Guoxi Ni ,&nbsp;Yanli Wang","doi":"10.1016/j.compfluid.2025.106770","DOIUrl":"10.1016/j.compfluid.2025.106770","url":null,"abstract":"<div><div>The radiative transfer equations (RTEs) are important in the study of inertial confinement fusion (ICF). Cylindrical configurations are commonly employed in ICF studies, such as at the National Ignition Facility. Therefore we focus on numerical schemes for RTEs in cylindrical coordinates. Based on the unified gas-kinetic scheme (UGKS), a positive-preserving and asymptotic-preserving scheme is proposed. First, the kinetic equation in RTEs is decomposed into the rotation part and the transport-absorption part using a splitting strategy. The rotation part is solved using the positive-preserving semi-Lagrangian method. The positive-preserving scheme for the transport-absorption part is derived by establishing the equivalence between the time evolution solver and the update formula. Compared to previous studies, our scheme enables arbitrarily high-order reconstruction in both spatial and velocity spaces while preserving the positive-preserving property. Additionally, the asymptotic-preserving property is proven. Various numerical experiments confirm the high-order accuracy, positive-preserving property, and asymptotic-preserving property of our scheme.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106770"},"PeriodicalIF":3.0,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810659","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}

{"title":"Direct numerical simulation of smooth-body flow separation around a ramp","authors":"Ali Uzun ,&nbsp;Mujeeb R. Malik","doi":"10.1016/j.compfluid.2025.106779","DOIUrl":"10.1016/j.compfluid.2025.106779","url":null,"abstract":"<div><div>Spanwise-periodic computation of a turbulent flow past a two-dimensional smooth ramp geometry is performed in the form of a direct numerical simulation. The Reynolds number based on the ramp height is about 147,000. A straight section that precedes the smooth ramp allows the incoming turbulent boundary layer to grow under a weak favorable pressure gradient. The boundary layer introduced at the domain inlet has a momentum-thickness based Reynolds number of 2000. The turbulent boundary layer nearing the ramp first interacts with a relatively stronger favorable pressure gradient, followed by a strong adverse pressure gradient. Consequently, the boundary layer experiences a modest acceleration before decelerating and separating. Analysis of the data over this region hints at the formation of an internal layer beneath the accelerated boundary layer. The analysis also reveals that this internal layer forms the origin of the free shear layer that emerges in the deceleration region and separates. The streamwise extent of the separated region is comparable to the ramp length, while the viscous layer thickness near reattachment is about the same as the ramp height; hence, the boundary layer undergoing separation and subsequent reattachment in the present configuration experiences its thickness being amplified by about tenfold. The reattached flow continues to develop further under a diminishing pressure gradient in the recovery region in a similar fashion to a zero pressure gradient turbulent boundary layer.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106779"},"PeriodicalIF":3.0,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852476","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}

{"title":"Hybrid quantum physics-informed neural network: Towards efficient learning of high-speed flows","authors":"Fong Yew Leong,&nbsp;Wei-Bin Ewe,&nbsp;Si Bui Quang Tran,&nbsp;Zhongyuan Zhang,&nbsp;Jun Yong Khoo","doi":"10.1016/j.compfluid.2025.106782","DOIUrl":"10.1016/j.compfluid.2025.106782","url":null,"abstract":"<div><div>This study benchmarks hybrid quantum physics-informed neural network (HQPINN) to model high-speed flows, compared against classical physics-informed neural networks (PINNs) and fully quantum neural networks (QNNs). The HQPINN architecture integrates a parameterized quantum circuit (PQC) with a classical neural network in parallel, trained via a physics-informed loss. Across harmonic, non-harmonic, and transonic benchmarks, HQPINNs demonstrate balanced performance, offering competitive accuracy and stability with reduced parameter cost. Quantum PINNs are highly efficient for harmonic problems achieving the lowest loss with minimal parameters due to their Fourier structure, but struggle to generalize in non-harmonic settings involving shocks and discontinuities. HQPINNs mitigate such artifacts, and with sufficient parameterization, can match the performance of classical models in more complex regimes. Although constrained by current quantum emulation costs and scalability, HQPINNs show promise as general-purpose solvers, offering parameter efficiency with robust fallback behavior, particularly suited for problems where the nature of the solution is not known <em>a-priori</em>.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106782"},"PeriodicalIF":3.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144842369","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}

{"title":"Eulerian modeling of compressible multicomponent elastic materials","authors":"A. Serezhkin,&nbsp;I. Menshov","doi":"10.1016/j.compfluid.2025.106778","DOIUrl":"10.1016/j.compfluid.2025.106778","url":null,"abstract":"<div><div>An Eulerian numerical model is developed for calculating dynamic processes in multimaterial elastic media. Accurate and correct description of the interaction of materials on the surface of the interface and the dynamics of the interface itself is inevitably required. Problems with large deformation of the interface cause serious difficulty when using Lagrangian numerical methods as they lead to strong distortion of the computational grid and loss of the accuracy. For such problems, so-called diffuse interface models are more preferred allowing one to track the interface and calculate the propagation of perturbations due to the interaction of materials on a fixed grid with a larger degree of accuracy. However, most of such models consider the dynamics of the medium in the hydrodynamic approach. The present paper is devoted to the extension of the class of diffuse interface models to the elastoplastic rheology of materials. The two-material model proposed is basically the extension of the hydrodynamic Baer–Nunziato two-phase model to hypoelastic materials. Numerical results demonstrate the capabilities of the model to accurately simulate wave processes in multimaterial media.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106778"},"PeriodicalIF":3.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829071","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}

{"title":"Cavitation dynamics and surface erosion in fuel injectors considering the composition of fuel mixtures","authors":"Raffaele Bellini,&nbsp;Carlos Rodriguez,&nbsp;Ioannis K. Karathanassis,&nbsp;Manolis Gavaises","doi":"10.1016/j.compfluid.2025.106793","DOIUrl":"10.1016/j.compfluid.2025.106793","url":null,"abstract":"<div><div>Cavitation and cavitation-induced erosion depend on fuel properties and operating conditions. The majority of studies on cavitation consider simple thermodynamic Equations of State (EoS), which limit the analysis of thermal effects occurring at high pressures and temperatures prevailing during bubble collapse. This can affect simulation fidelity, particularly when comparing fuels of different thermodynamic properties. The goal of this work is to examine, with the use of real-fluid thermodynamic models, pressure peaks and thermal effects owing to cavitation collapse in the vicinity of solid boundaries. A structured table is used to reconstruct the thermodynamic properties of the working fluids examined based on the Helmholtz Energy Equation of State. The table is incorporated into an explicit, density-based solver in OpenFOAM, using a Mach-consistent numerical flux for subsonic up to supersonic flow conditions. Different test cases have been considered to demonstrate the capabilities of the implemented methodology including a simple validation of the solver against the Riemann problem, a single spherical bubble of dodecane case collapsing in an infinite medium, a single spherical bubble collapsing close to a wall and a cluster of spherical bubbles collapsing close to a rigid wall. The ultimate objective of the research framework is to simulate bubble-collapse behaviour at pressure and temperature conditions relevant to Dual Fuel Internal Combustion Engines using different fuels. Thus, the present work aims to provide insight on cavitation evolution and relevant influence on injector reliability to eventually produce design guidelines for environmentally friendlier powertrains.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106793"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144878580","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}

{"title":"Multidimensional HLLI generalized riemann problem solver for conservation laws – The two-dimensional case for structured meshes","authors":"Dinshaw S. Balsara ,&nbsp;Deepak Bhoriya","doi":"10.1016/j.compfluid.2025.106791","DOIUrl":"10.1016/j.compfluid.2025.106791","url":null,"abstract":"<div><div>The Riemann problem, and the associated generalized Riemann problem (GRP), are increasingly seen as important building blocks for modern higher order Godunov-type schemes. While most solutions of the GRP are specific to a particular hyperbolic law, a general-purpose GRP that can be applied to any hyperbolic conservation law has emerged in the form of the one-dimensional HLLI-GRP. Approximate multidimensional Riemann solvers have also been designed by the first author and his colleagues. However, a multidimensional GRP that is applicable to any hyperbolic conservation law has never been designed until now to the best of our knowledge. It this paper, we accomplish such a task.</div><div>The study of the multidimensional Riemann problem entails the study of the strongly-interacting state. Starting with the multidimensional HLL-based Riemann solver, we present all the steps for endowing spatial gradients to the strongly-interacting state. This is accomplished through application of Rankine-Hugoniot shock jump conditions to the higher order terms in a Taylor series expansion of the strongly-interacting state. A linearized formulation is also used to obtain the spatial gradients to the strongly-interacting state. With the spatial gradients in hand, it is possible to specify the multidimensional HLL flux as well its time-derivative. This results in a multidimensional HLL-GRP solver. We then utilize intermediate waves to reduce the dissipation of the multidimensional HLL-GRP. This gives us an HLLI-GRP solver which significantly reduces dissipation and is complete in multiple dimensions.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106791"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144878581","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}

{"title":"A mesh-based Graph Neural Network approach for surrogate modeling of Lagrangian free surface fluid flows","authors":"Federico Lanteri,&nbsp;Massimiliano Cremonesi","doi":"10.1016/j.compfluid.2025.106773","DOIUrl":"10.1016/j.compfluid.2025.106773","url":null,"abstract":"<div><div>The study of free surface fluid flows is of significant interest across various research fields, including civil, aerospace, and biomedical engineering. Among the numerical methods used to address free surface problems, the Particle Finite Element Method (PFEM) stands out as a robust and efficient approach. PFEM solves the governing equations using the standard finite element method while addressing mesh distortion through a fast and efficient remeshing procedure.</div><div>In recent years, deep learning (DL) algorithms have demonstrated remarkable successes in learning from examples, and their application to datasets generated from numerical simulations could result in surrogate models able to reduce the computational cost of classical numerical methods. In the context of free surface fluid simulations, particularly noteworthy are attempts to employ Graph Neural Networks (GNNs) given their ability to process unstructured data that cannot be represented as structured grids, which are typical of these applications.</div><div>In this work, we introduce NeuralPFEM (NPFEM), a GNN-based approach for surrogate modeling of free surface fluid simulations. NPFEM learns the system’s temporal evolution in an autoregressive manner, preserving the same structure of a standard numerical solver. It inherits its hybrid nature from PFEM, combining features of particle-based and mesh-based methods. This hybrid approach distinguishes NPFEM from existing methods, such as the Graph Neural Simulator (GNS), which are purely particle-based. As a result, to construct the graph during training, NPFEM exploits the mesh connectivity already available in the dataset, while GNS must reconstruct graph connectivity at every training step based on particle distributions. During prediction, NPFEM employs PFEM mesh generation algorithm and particle redistribution tools to build the graph connectivity, ensuring a more uniform particle distribution within the domain and producing a mesh-based output solution. This approach preserves mesh quality and mitigates undesirable effects like particle clustering.</div><div>We evaluate the results both qualitatively and quantitatively, comparing them with those obtained from PFEM. Moreover, we compute physical quantities out of the learned solution. In particular, the output mesh structure, combined with the joint prediction of the velocity and the pressure fields, facilitates the calculation of forces and stresses, a first step in the direction of applying this kind of tool to Fluid–Structure Interaction (FSI) problems.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106773"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809707","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}

{"title":"A Knudsen layer correction model based on the lattice Boltzmann method","authors":"Yongjia Wu ,&nbsp;Ouyue Zhang ,&nbsp;Qinggang Wang ,&nbsp;Xinyi Yang ,&nbsp;Donghao Zhao ,&nbsp;Tingzhen Ming","doi":"10.1016/j.compfluid.2025.106795","DOIUrl":"10.1016/j.compfluid.2025.106795","url":null,"abstract":"<div><div>The lattice Boltzmann method (LBM), widely applied in microscale flow research, faces challenges in accurately capturing gas slip effects despite studies on the Knudsen layer, as existing or modified models often suffer from complexity and limited accuracy. This study presents a simple correction function model that accounts for solid wall effects and accurately captures the slip behavior of the fluid. A sensitivity analysis of its three adjustable parameters, C₁​, C_2<!-->, and C₃​, reveals that C₁​ has the most significant influence on the dimensionless mass flow rate, followed by C₂​, while C₃​ has the least impact. The optimal parameter values are determined accordingly as C₁=1.8, C₂=1.6, and C₃=0.1. The improved model is applied to modeling the Poiseuille flow between two parallel plates in the transition regime. The results indicate that the bulk velocity and wall slip velocity obtained using this model exhibit excellent agreement with reference values derived from the solution of the linearized Boltzmann equation. By optimizing the slip velocity, the relative deviation is reduced to within 2.5 % in the small Knudsen number range of the transition regime (<span><math><mrow><mi>K</mi><mi>n</mi><mo>≤</mo><mn>1.1284</mn></mrow></math></span>), with a minimum error of only 0.7 % at certain Knudsen numbers. In the large Knudsen number range (<span><math><mrow><mi>K</mi><mi>n</mi><mo>&gt;</mo><mn>1.1284</mn></mrow></math></span>), the relative deviation remains within 5 %. Simulations of pressure-driven flow and flow past a square cylinder further demonstrated that the model attained satisfactory accuracy, thereby validating its predictive capability. These results indicated that the improved model accurately captured Knudsen layer effects, gas slip phenomena, and compressibility effects.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106795"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144842368","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}

{"title":"A generalized modular grad-div Picard iteration for the incompressible Navier–Stokes equations","authors":"Qi Zhang,&nbsp;Pengzhan Huang,&nbsp;Yinnian He","doi":"10.1016/j.compfluid.2025.106769","DOIUrl":"10.1016/j.compfluid.2025.106769","url":null,"abstract":"<div><div>In this paper, we propose a generalized modular grad-div Picard iterative method for the stationary Navier–Stokes equations describing the motion of a viscous incompressible fluid. The innovative approach integrates an intrusive module into existing Navier–Stokes solver codes. This integration not only enhances the capability to handle problems with higher Reynolds numbers but also effectively mitigates solver failures and improves computational efficiency as the grad-div parameter increases. Furthermore, we provide analysis of stability and convergence. Finally, several numerical experiments are conducted to validate the theoretical findings and demonstrate the advantage of the proposed method.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106769"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809708","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}