Journal of Computational Physics最新文献

{"title":"An electromagnetic model in SOLEDGE3X for edge plasma turbulence simulations in tokamaks","authors":"Raffael Düll ,&nbsp;Hugo Bufferand ,&nbsp;Eric Serre ,&nbsp;Guido Ciraolo ,&nbsp;Virginia Quadri ,&nbsp;Nicolas Rivals ,&nbsp;Frederic Schwander ,&nbsp;Patrick Tamain","doi":"10.1016/j.jcp.2025.114052","DOIUrl":"10.1016/j.jcp.2025.114052","url":null,"abstract":"<div><div>Even small fluctuations in the magnetic field are known to impact edge plasma turbulence and transport properties in magnetic confinement fusion devices. Magnetic induction modifies the parallel electric field, and as such, it impacts the parallel current in Ohm’s law. In addition, magnetic fluctuations can induce geometrical and topological changes in the magnetic field structure, leading to parallel transport across the equilibrium magnetic surfaces. This paper presents the new drift-reduced fluid electromagnetic model implemented in SOLEDGE3X [Bufferand <em>et al.</em>, Nuc. Fus. 2021]. Based on a domain decomposition, a specific numerical scheme is proposed using conservative second-order finite volumes associated with a semi-implicit time advancement. The coupling between the parallel current <span><math><msub><mi>j</mi><mo>∥</mo></msub></math></span> and the parallel electromagnetic potential <span><math><msub><mi>A</mi><mo>∥</mo></msub></math></span> in Ohm’s and Ampere’s laws is treated using a new toroidally and poloidally staggered grid. While adding <span><math><msub><mi>A</mi><mo>∥</mo></msub></math></span> doubles the size of the vorticity operator to be inverted, numerical tests show that the inclusion of the finite mass of the electrons in the new model acts as an upper limit on the parallel diffusion coefficient, thus improving the conditioning of the matrix at high plasma temperatures when the parallel resistivity <span><math><msub><mi>η</mi><mo>∥</mo></msub></math></span> approaches zero. The changes in the algorithm are verified using the method of manufactured solutions. The implementation is first validated with respect to theoretical linear stability results, recovering the transition from Alfvén to thermal electron waves as the perpendicular wavenumber increased. Comparisons with available results in the literature show a qualitative agreement on a single blob propagation in a limited slab geometry. The first 3D simulations of plasma edge turbulence in TCV demonstrate the capability of the new solver to handle realistic tokamak configurations. The explicit-implicit time integration scheme enables one to compare electrostatic and electromagnetic effects using the same solver, with or without electron inertia and magnetic flutter. This ability opens the way to a better understanding of the impact of the electrostatic and electromagnetic mechanisms on the transport and turbulence properties in realistic tokamak configurations.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"536 ","pages":"Article 114052"},"PeriodicalIF":3.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HLLC solver for the topology based multiphase flow model","authors":"Ido Silverman","doi":"10.1016/j.jcp.2025.114051","DOIUrl":"10.1016/j.jcp.2025.114051","url":null,"abstract":"<div><div>The topology based multi-fluid flow model of Silverman (Silverman, Nuclear Engineering and Design, 2021, Vol. 383, pp. 111421) presents a unified model that is able to correctly describe the interactions between the fluids in the flow field for any flow topology (i.e. dispersed or separated flows). This model can simulate the flow starting from single-fluid conditions, moving to dispersed flows and up to separated fluids flow. To apply this model to general multi-fluid simulations, a revised version of the HLLC flow solver is developed here. A few benchmarks present the ability of the new model and solver to simulate compressible multi-fluid flows. Some of the results presented here indicate that the topology of a multi-fluid mixture has an effect on its stability and structure.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"536 ","pages":"Article 114051"},"PeriodicalIF":3.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144068172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new velocity reconstruction algorithm for multiphase flows with moving bodies","authors":"Yichen Huang ,&nbsp;Bin Xie","doi":"10.1016/j.jcp.2025.114048","DOIUrl":"10.1016/j.jcp.2025.114048","url":null,"abstract":"<div><div>A new velocity reconstruction scheme is proposed to reconstruct the cell-centered velocity field with second-order accuracy through the given surface field of velocity vectors, and then incorporated into a high-fidelity numerical model to solve the incompressible Navier–Stokes equations in the arbitrary Lagrangian-Eulerian (ALE) formulation on unstructured grids. Different from the conventional model that reconstructs the centroidal velocity variation from the surface normal pressure gradients with the conventional balanced-force (CBF) algorithm in the entire domain, the present model employs two different schemes in the interface and non-interface regions. In the interface region, the cell-centered velocity variation is reconstructed with the surface normal pressure gradients calculated by the generic balanced-force (GBF) algorithm to suppress the non-physical flow generated by the imbalanced discretization between pressure gradient and external forces with CBF algorithm on non-orthogonal grids; In the non-interface region, the proposed second-order velocity reconstruction scheme for velocity variation is enabled by acquiring the surface field of pressure gradient vectors with adequate precision through the modification of pressure Poisson equation. The resulting model is able to effectively suppress the instability induced by the mesh deformation and the nonlinearity in fluid-structure interaction (FSI), and capture the flow structure with satisfactory energy conservation and higher accuracy. Various numerical examples have demonstrated that the present algorithm and computational framework offer a promising platform to provide more accurate and robust predictions of the flow field and the rigid body motion for multiphase FSI flows on unstructured grids.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"535 ","pages":"Article 114048"},"PeriodicalIF":3.8,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lattice Boltzmann simulation of droplet collisions at various angles in the presence of a non-condensable gas","authors":"Hailin Xu,&nbsp;Yuxin Wang","doi":"10.1016/j.jcp.2025.114033","DOIUrl":"10.1016/j.jcp.2025.114033","url":null,"abstract":"<div><div>Due to its simple concept and high computational efficiency, the pseudo-potential multiphase lattice Boltzmann (LB) model applied to high-density two- component flow has attracted great attention in recent years. In this work, a multi-component/multi-phase (MCMP) LB method with gas/liquid coexistence is proposed. Two state equations are incorporated in the pseudo-potential function, namely the Peng-Robinson (PR) state equation for water and the ideal gas state equation for non-condensable gas (NCG). Based on this newly developed MCMP LB model, the collision of two equal-sized liquid droplets in the presence of NCG is simulated. By simulating the state of stationary liquid droplets and the collision characteristics of the water droplets collision in air, the density distribution of gas/liquid, droplet sizes, ambient temperature, pressure difference inside and outside the droplets, and the regimes of collision outcomes exhibited by two water droplets colliding in air are numerically obtained. The relationships between various parameters and the collision outcomes are in good agreement with an existing analytical model, validating the correctness and accuracy of this newly developed MCMP LB model. Since this novel model does not involve any approximation/assumption or use empirical correlations for interface mass transfer, the results can be considered as the first attempt at direct numerical simulation of droplet collisions in the presence of NCG.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"535 ","pages":"Article 114033"},"PeriodicalIF":3.8,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143924700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A far-field boundary condition for measuring drag force on micro/nano particles","authors":"Giorgos Tatsios ,&nbsp;Nikos Vasileiadis ,&nbsp;Livio Gibelli ,&nbsp;Matthew K. Borg ,&nbsp;Duncan A. Lockerby","doi":"10.1016/j.jcp.2025.114034","DOIUrl":"10.1016/j.jcp.2025.114034","url":null,"abstract":"<div><div>Predicting the flow around airborne particles smaller than 1 µm, which is essential for many air-quality control applications, is challenging because the flow is both rarefied (due to the particle size approaching the mean free path of the gas) and characterised by very low Reynolds numbers (due to the small velocities and length scales involved). The accurate measurement of the drag force on these particles requires the solution of the Boltzmann equation, typically performed using the Direct Simulation Monte Carlo (DSMC) method. In the conventional formulation of these simulations, an accurate value of drag force can only be obtained if the domain boundaries in the DSMC simulation are placed at very large distances from the particle; using small domains can significantly over-predict the drag. The computational cost of DSMC simulations scales with the cube of the domain size for a general 3D flow, making it computationally intractable to measure drag on particles of arbitrary shape in the transition regime. In this work, we propose a boundary condition that emulates the flow conditions at a finite distance from the particle, rather than the free-stream conditions commonly used in previous studies. Our approach exploits the fact that the flow disturbance far from an arbitrary particle, travelling at very low Reynolds number, has a known analytical form that is given by the fundamental solution to the Stokes equations. Employing this boundary condition enables accurate simulations of drag prediction using much smaller domain sizes than otherwise possible, decreasing the computational cost by up to three orders of magnitude. The proposed approach allows the first accurate and tractable calculation of the drag force on slow-moving arbitrary-shaped 3D particles in the transition regime.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"535 ","pages":"Article 114034"},"PeriodicalIF":3.8,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-order WENO finite-difference methods for hyperbolic nonconservative systems of partial differential equations","authors":"Baifen Ren ,&nbsp;Carlos Parés","doi":"10.1016/j.jcp.2025.114047","DOIUrl":"10.1016/j.jcp.2025.114047","url":null,"abstract":"<div><div>This work aims to extend the well-known high-order WENO finite-difference methods for systems of conservation laws to nonconservative hyperbolic systems. The main difficulty of these systems both from the theoretical and the numerical points of view comes from the fact that the definition of weak solution is not unique: according to the theory developed by Dal Maso, LeFloch, and Murat in 1995, it depends on the choice of a family of paths. A new strategy is introduced here that allows non-conservative products to be written as the derivative of a generalized flux function that is defined locally on the basis of the selected family of paths. WENO reconstructions are then applied to this generalized flux. Moreover, if a Roe linearization is available, the generalized flux function can be evaluated through matrix-vector operations instead of path-integrals. Two different known techniques are used to extend the methods to problems with source terms and the well-balanced properties of the resulting schemes are studied. These numerical schemes are applied to a coupled Burgers’ system and to the two-layer shallow water equations in one- and two- dimensions to obtain high-order methods that preserve water-at-rest steady states.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"535 ","pages":"Article 114047"},"PeriodicalIF":3.8,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143924699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extension of the consistent δ+-SPH model for multiphase flows considering the compressibility of different phases","authors":"Xiao-Ting Huang ,&nbsp;Peng-Nan Sun ,&nbsp;Hong-Guan Lyu ,&nbsp;Andrea Colagrossi ,&nbsp;A-Man Zhang","doi":"10.1016/j.jcp.2025.114031","DOIUrl":"10.1016/j.jcp.2025.114031","url":null,"abstract":"<div><div>In hydrodynamic problems involving wave impact on structures, air compressibility is crucial for accurate pressure prediction when air bubbles are entrapped. In this work, the consistent <span><math><msup><mrow><mi>δ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>-SPH model, originally developed for single-phase scenarios, is extended to multiphase contexts. Although the consistent <span><math><msup><mrow><mi>δ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>-SPH model shows good performance for single phase and viscous flow simulations, extending it to multiphase scenarios presents challenges, such as proper implementation of particle shifting for multiphase interfaces. Therefore, within the framework of the consistent <span><math><msup><mrow><mi>δ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>-SPH, we introduce the following enhancements: firstly, new strategies for handling <span><math><mi>δ</mi><mi>u</mi></math></span>-terms given by the particle shifting technique at multiphase interfaces are proposed to maintain stability and conservation. Secondly, for modeling of incompressible phases, like water, an acoustic damper term is introduced to alleviate acoustic waves resulting from the weakly-compressible assumption, which is expected to achieve smooth pressure field comparable to truly-incompressible hypothesis, thereby reducing the nonphysical pressure wave during the violent impact state; for modeling compressible phases like air, a physical sound speed is adopted in the equation of state to accurately model real gas phase compressibility. To test and validate the present multiphase SPH model, simulations were conducted for six scenarios. In particular, except for sloshing with two-layer liquids, the other scenarios fully consider air pressure oscillations when air is entrapped, compressed, or expanded by surrounding flows. The results demonstrate significant advantages of the present SPH model in simulating multiphase problems involving strong liquid impact and different phase compressibility.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"535 ","pages":"Article 114031"},"PeriodicalIF":3.8,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Boundary integral methods for particle diffusion in complex geometries: Shielding, confinement, and escape","authors":"Jesse Cherry ,&nbsp;Alan E. Lindsay ,&nbsp;Bryan D. Quaife","doi":"10.1016/j.jcp.2025.114032","DOIUrl":"10.1016/j.jcp.2025.114032","url":null,"abstract":"<div><div>We present a numerical method for the solution of diffusion problems in unbounded planar regions with complex geometries of absorbing and reflecting bodies. Our numerical method applies the Laplace transform to the parabolic problem, yielding a modified Helmholtz equation which is solved with a boundary integral method. Returning to the time domain is achieved by quadrature of the inverse Laplace transform by deforming along the so-called Talbot contour. We demonstrate the method for various complex geometries formed by disjoint bodies of arbitrary shape on which either uniform Dirichlet or Neumann boundary conditions are applied. The use of the Laplace transform bypasses constraints with traditional time-stepping methods and allows for integration over the long equilibration timescales present in diffusion problems in unbounded domains. Using this method, we demonstrate shielding effects where the complex geometry modulates the dynamics of capture to absorbing sets. In particular, we show examples where geometry can guide diffusion processes to particular absorbing sites, obscure absorbing sites from diffusing particles, and even find the exits of confining geometries, such as mazes.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"534 ","pages":"Article 114032"},"PeriodicalIF":3.8,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sparse flow reconstruction methods to reduce the costs of analyzing large unsteady datasets","authors":"Spencer L. Stahl ,&nbsp;Stuart I. Benton","doi":"10.1016/j.jcp.2025.114037","DOIUrl":"10.1016/j.jcp.2025.114037","url":null,"abstract":"<div><div>The cost of writing, transferring, and storing large amounts of data from unsteady simulations limits the accessibility of the entire solution, often leaving the majority of the flow under-sampled or not analyzed. For example, modeling the transient behavior of rare, but important, dynamic events requires three-dimensional snapshots written at high sampling rates, over a long duration. As such, the simulation time needed and large quantity of data produced, makes this a challenging problem for practical computational fluid dynamic (CFD) workflows, where memory resources are often limited and the writing penalty for modern GPU computing is much costlier. In this work, multiple sparse flow reconstruction (SFR) methods are developed to approximate a full unsteady solution by writing far fewer sparse measurements from the CFD solver, thus diminishing writing costs, data storage, and enabling greater sampling rates. SFR is motivated by a large-eddy simulation (LES) example pursuing rare inlet distortion events, demonstrating that a down-sampling in full snapshots, supplemented by high-frequency sparse measurements, can substantially reduce writing time for a GPU solver and nearly eliminate the writing cost for a CPU solver. In its simplest form, the “snapshot” SFR method is a single equation and can be further compressed with Proper Orthogonal Decomposition (POD-SFR) or its smaller and faster double POD-SFR variant. A streaming SFR modification reconstructs snapshots more efficiently when local memory cannot store the entire solution. A sensitivity study evaluates the SFR scaling trade-off between sparse sampling rates and reconstruction accuracy, outlining best practices. To offset error of using random sparse measurements, the SFR approach exactly preserves dynamics in designated flow regions by additionally specifying sparse measurement locations, used here to capture the inlet distortion events. Distortion events are evaluated using the conditional space-time proper orthogonal decomposition (CST-POD) to pursue physical insights that characterize the upstream causality at full resolution. A validation study of CST-POD modes confirms SFR effectiveness at retaining the event dynamics with substantial computational and memory savings.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"534 ","pages":"Article 114037"},"PeriodicalIF":3.8,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143890513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Navier–Stokes characteristic boundary conditions for real fluids with kinetic-energy- and pressure-equilibrium-preserving schemes","authors":"Zhen Li ,&nbsp;Ahmed Abdellatif ,&nbsp;Rui Yang ,&nbsp;Lluís Jofre ,&nbsp;Francesco Capuano","doi":"10.1016/j.jcp.2025.114035","DOIUrl":"10.1016/j.jcp.2025.114035","url":null,"abstract":"<div><div>This study presents Navier–Stokes characteristic boundary conditions (NSCBC) for real fluids in conjunction with kinetic-energy-preserving (KEP) and pressure-equilibrium-preserving (PEP) numerical schemes. The appropriate wave relations are derived for an arbitrary equation of state according to either the locally one-dimensional inviscid (LODI) approximation or its three-dimensional extension. The NSCBC workflow is adapted to the PEP framework, which in this work is based on evolving pressure instead of total energy. A set of canonical tests of increasing complexity demonstrates that the combination of KEP+PEP schemes and 3D-NSCBC is a viable approach to obtain stable numerical results that are free of spurious oscillations/reflections, in the absence of any artificial stabilization mechanism.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"535 ","pages":"Article 114035"},"PeriodicalIF":3.8,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143913175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}