Journal of Computational Physics最新文献

{"title":"A marching cubes based method for topology changes in three-dimensional two-phase flows with front tracking","authors":"Gabriele Gennari ,&nbsp;Christian Gorges ,&nbsp;Fabian Denner ,&nbsp;Berend van Wachem","doi":"10.1016/j.jcp.2025.114284","DOIUrl":"10.1016/j.jcp.2025.114284","url":null,"abstract":"<div><div>The handling of topology changes in two-phase flows, such as breakup or coalescence of interfaces, with front tracking is a well-known problem that requires an additional effort to perform explicit manipulations of the Lagrangian front. In this work, we present an approach that allows to perform topology changes with interfaces made of connected triangular elements. The methodology consists of replacing the fluid entities that undergo breakup/coalescence with the iso-surface corresponding to the indicator function value <span><math><mrow><mi>I</mi><mo>=</mo><mn>0.5</mn></mrow></math></span>, which automatically returns the shape of the bodies after topology changes. The generation and triangulation of such surface is obtained by exploiting the marching cubes algorithm. Since we perform the reconstruction of the interface only for the bodies that experience breakup/coalescence, the increase in computational cost with respect to a classic front tracking scheme without topology changes is small. Using validation cases, we show that the proposed reconstruction procedure is second-order accurate for volume conservation and able to capture the physics of several two-phase flow configurations undergoing topology changes. The validation cases include the breakup of a droplet in simple shear flow and two rising bubbles in different regimes (peripheral and central breakups). Coalescence is tested by modelling the binary collision between two droplets. For the selected validation cases, an excellent agreement between the numerical results and experiments is observed. The proposed methodology is able to capture the details of such interfacial flows, by predicting accurately the coalescence/breakup dynamics, as well as the number, size and shapes of satellite droplets/bubbles after topology changes.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114284"},"PeriodicalIF":3.8,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867508","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":"Lagrangian hybrid element particle method (LHEPM) for incompressible fluid dynamics","authors":"Huangcheng FANG,&nbsp;Zhen-Yu YIN","doi":"10.1016/j.jcp.2025.114281","DOIUrl":"10.1016/j.jcp.2025.114281","url":null,"abstract":"<div><div>Traditional numerical approaches for solving incompressible fluid dynamics problems face notable limitations, including convective instability and interface tracking in Eulerian approaches, severe element distortion in Lagrangian mesh-based methods, and reduced computational accuracy in particle-based approaches. To overcome these challenges, this paper develops a new Lagrangian Hybrid Element Particle Method (LHEPM) that combines two discretization schemes: underlying elements and material particles. The underlying elements, designed without storing historical variables, can be dynamically regenerated during the computation. These elements serve as temporary tools for discretizing physical fields within the computational domain, with their spatial interpolation subsequently reconstructed onto the particles via a kernel function. The proposed framework permits the seamless incorporation of diverse finite element techniques, such as boundary condition enforcement, contact algorithms, and pressure stabilization, without requiring modifications. The effectiveness and performance of LHEPM are validated through its application to several standard fluid problems. Compared to other state-of-the-art methods, the proposed LHEPM avoids the need for complex treatment of convective terms and free-surface tracking typically required in Eulerian mesh-based approaches, such as the finite volume method (FVM); its unique interpolation technique and optimal particle integration enable significantly higher accuracy than particle-based methods like Smoothed Particle Hydrodynamics (SPH); dynamic mesh regeneration further resolves the mesh distortion issues inherent in traditional Lagrangian finite element method (FEM), making the proposed method a precise, efficient, and robust framework for incompressible fluid dynamics simulations.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"541 ","pages":"Article 114281"},"PeriodicalIF":3.8,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896569","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":"Preconditioning for a Cahn–Hilliard–Navier–Stokes model for morphology formation in organic solar cells","authors":"Pelin Çiloğlu ,&nbsp;Carmen Tretmans ,&nbsp;Roland Herzog ,&nbsp;Jan-F. Pietschmann ,&nbsp;Martin Stoll","doi":"10.1016/j.jcp.2025.114280","DOIUrl":"10.1016/j.jcp.2025.114280","url":null,"abstract":"<div><div>We present a model for the morphology evolution of printed organic solar cells, which occurs during the drying of a mixture of polymer, non-fullerene acceptor, and solvent. Our model uses a phase field approach coupled to a Navier–Stokes equation describing the macroscopic movement of the fluid. Additionally, we incorporate the evaporation process of the solvent using an Allen–Cahn equation. The model is discretized using a finite-element approach with a semi-implicit discretization in time. The resulting (non)linear systems are coupled and of large dimensionality. We present a preconditioned iterative scheme to solve them robustly with respect to changes in the discretization parameters. We illustrate that the preconditioned solver shows parameter-robust iteration numbers and that the model qualitatively captures the behavior of the film morphology during drying.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114280"},"PeriodicalIF":3.8,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829338","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":"Rescaled equations for well-conditioned direct numerical simulations of rapidly rotating convection","authors":"Keith Julien ,&nbsp;Adrian van Kan ,&nbsp;Benjamin Miquel ,&nbsp;Edgar Knobloch ,&nbsp;Geoffrey Vasil","doi":"10.1016/j.jcp.2025.114274","DOIUrl":"10.1016/j.jcp.2025.114274","url":null,"abstract":"<div><div>Convection is a ubiquitous process driving geophysical/astrophysical fluid flows, which are typically strongly constrained by planetary rotation on large scales. A celebrated model of such flows, rapidly rotating Rayleigh–Bénard convection, has been extensively studied in direct numerical simulations (DNS) and laboratory experiments, but the parameter values attainable by state-of-the-art methods are limited to moderately rapid rotation (Ekman numbers <span><math><mrow><mi>E</mi><mi>k</mi><mo>≳</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>8</mn></mrow></msup></mrow></math></span>), while realistic geophysical/astrophysical <span><math><mrow><mi>E</mi><mi>k</mi></mrow></math></span> are significantly smaller. Asymptotically reduced equations of motion, the nonhydrostatic quasi-geostrophic equations (NHQGE), describing the flow evolution in the limit <span><math><mrow><mi>E</mi><mi>k</mi><mo>→</mo><mn>0</mn></mrow></math></span>, do not apply at finite rotation rates. The geophysical/astrophysical regime of small but finite <span><math><mrow><mi>E</mi><mi>k</mi></mrow></math></span> therefore remains currently inaccessible. Here, we introduce a new, numerically advantageous formulation of the Navier–Stokes–Boussinesq equations informed by the scalings valid for <span><math><mrow><mi>E</mi><mi>k</mi><mo>→</mo><mn>0</mn></mrow></math></span>, the <em>Rescaled Rapidly Rotating incompressible Navier–Stokes Equations</em> (RRRiNSE). We solve the RRRiNSE using a spectral quasi-inverse method resulting in a sparse, fast algorithm to perform efficient DNS in this previously unattainable parameter regime. We validate our results against the literature across a range of <span><math><mrow><mi>E</mi><mi>k</mi></mrow></math></span>, and demonstrate that the algorithmic approaches taken remain accurate and numerically stable at <span><math><mrow><mi>E</mi><mi>k</mi></mrow></math></span> as low as <span><math><msup><mn>10</mn><mrow><mo>−</mo><mn>15</mn></mrow></msup></math></span>. Like the NHQGE, the RRRiNSE derive their efficiency from adequate conditioning, eliminating spurious growing modes that otherwise induce numerical instabilities at small <span><math><mrow><mi>E</mi><mi>k</mi></mrow></math></span>. We show that in sufficiently large domains the time derivative of the mean temperature is inconsequential for accurately determining the Nusselt number in the stationary state, significantly reducing the required simulation time and leading to improved stability of our numerical formulation. We furthermore demonstrate that full DNS using RRRiNSE agree with the NHQGE at very small <span><math><mrow><mi>E</mi><mi>k</mi></mrow></math></span>.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"541 ","pages":"Article 114274"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896570","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":"Multicontinuum splitting scheme for multiscale flow problems","authors":"Yalchin Efendiev ,&nbsp;Wing Tat Leung ,&nbsp;Buzheng Shan ,&nbsp;Min Wang","doi":"10.1016/j.jcp.2025.114265","DOIUrl":"10.1016/j.jcp.2025.114265","url":null,"abstract":"<div><div>In this paper, we propose multicontinuum splitting schemes for multiscale problems, focusing on a parabolic equation with a high-contrast coefficient. Using the framework of multicontinuum homogenization, we introduce spatially smooth macroscopic variables and decompose the multicontinuum solution space into two components to effectively separate the dynamics at different speeds (or the effects of contrast in high-contrast cases). By treating the component containing fast dynamics (or dependent on the contrast) implicitly and the component containing slow dynamics (or independent of the contrast) explicitly, we construct partially explicit time discretization schemes, which can reduce computational cost. The derived stability conditions are contrast-independent, provided the continua are chosen appropriately. Additionally, we discuss possible methods to obtain an optimized decomposition of the solution space, which relaxes the stability conditions while enhancing computational efficiency. A Rayleigh quotient problem in tensor form is formulated, and simplifications are achieved under certain assumptions. Finally, we present numerical results for various coefficient fields and different continua to validate our proposed approach. It can be observed that the multicontinuum splitting schemes enjoy high accuracy and efficiency.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114265"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829336","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":"Mass-conserving ghost cell immersed boundary method with multigrid for coupled Navier-Stokes solvers","authors":"Mark A. George,&nbsp;Nicholas Williamson,&nbsp;Steven W. Armfield","doi":"10.1016/j.jcp.2025.114276","DOIUrl":"10.1016/j.jcp.2025.114276","url":null,"abstract":"<div><div>Although simple to implement, ghost cell immersed boundary methods in their basic form do not conserve mass globally, even in a mass-conservative finite volume framework where local mass conservation is satisfied in the fluid domain. Reconstruction near solid boundaries with corners is also difficult. Furthermore, when used with coupled solvers on collocated grids, correct implementation of momentum weighted interpolation at the boundaries is not straightforward. The approach presented here overcomes these issues by combining a directional ghost cell method with a weighted face flux correction based on the global mass continuity error. The method is simple to implement and only requires the addition of source terms to the discrete equations. The method is used in a fully coupled FAS multigrid scheme where the immersed boundary is applied on all grid levels. The scheme has been verified and validated for a number of canonical steady incompressible flows, and excellent performance and efficiency is demonstrated with linear scaling with problem size.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114276"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829335","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":"Hybrid ISPH_GNN method for simulating violent wave-structure interactions using wave-only data for training","authors":"Ningbo Zhang,&nbsp;Shiqiang Yan,&nbsp;Qingwei Ma","doi":"10.1016/j.jcp.2025.114277","DOIUrl":"10.1016/j.jcp.2025.114277","url":null,"abstract":"<div><div>It has been well-known that the incompressible Smoothed Particle Hydrodynamics (ISPH) is a powerful method for simulating violent wave-structure interactions (WSIs) concerned in marine engineering. However it is time consuming, primarily due to the need of solving pressure Poisson’s equation (PPE) involved in this method. In our previous publications, we are first to propose a hybrid approach embedding the graph neural network (GNN) into ISPH method to form the hybrid ISPH_GNN method for simulating free-surface problems, where the GNN is employed to replace solving the PPE. We demonstrated that the computational time for evaluating the pressure using GNN can be of one order less than that spent by directly solving PPE to achieve similar level of accuracy. More importantly, we also demonstrated in our previous publications that the GNN trained only on data for wave-only (referring to no structure or obstacles in wave fields) cases can be satisfactorily applied to the cases for wave-floater interactions. However, what we have not previously studied is if the GNN trained only by using wave-only cases can be used for simulating violent WSIs. One of the original contributions of this paper is to answer this question. In addition, transfer learning has been proved to be a machine learning (ML) technique that can significantly enhance efficiency and improve the performance in other fields but has not been explored in the hybrid ISPH_GNN method. Another original contribution of this paper is to explore the potential of integrating transfer learning with the ISPH_GNN for simulating violent WSIs. Specifically, we will demonstrate that the GNN trained by using data from sloshing and dam-breaking cases without any structure (termed as wave-only data in this paper) can be employed to simulate more complex cases, such as water entry of an object, wave impact on a trapezoidal structure and wave interaction with an oscillating wave surge converter, all of which involve violent WSIs. We will also demonstrate that the transfer learning technique with use of a small volume of additional data has a potential in enhancing the prediction accuracy of the ISPH_GNN. Furthermore, we will show that the ISPH_GNN significantly reduces computational time for pressure evaluation in violent WSI cases, even with a more significant reduction compared to wave-floater interaction cases studied in our previous work. These highlight the strong potential of the ISPH_GNN for broad applications in marine engineering, opening a novel route to employ ML without need of generating data for very complex cases of violent WSIs.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114277"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841333","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":"On the ground states of rotating two-component dipolar Bose–Einstein condensates","authors":"Wenlei Li ,&nbsp;Qinglin Tang ,&nbsp;Jing Wang ,&nbsp;Yong Zhang ,&nbsp;Ruijie Zou","doi":"10.1016/j.jcp.2025.114275","DOIUrl":"10.1016/j.jcp.2025.114275","url":null,"abstract":"<div><div>In this paper, we focus on the ground states of rotating two-component dipolar Bose–Einstein condensates. To begin with, we investigate the existence and uniqueness of the ground states with rigorous proofs. Then, we construct a spectrally accurate and efficient numerical scheme by integrating the gradient flow with Lagrange multiplier (GFLM) method and the optimal Kernel Truncation method (KTM) for Dipole-Dipole Interaction (DDI) evaluation to compute the ground states. Finally, we confirm the spectral accuracy, and extensive numerical results are presented to study the effects of different model parameters on the ground states, including the mass distribution, short-range interaction strength, angular velocity and anisotropic trapping potential.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114275"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810112","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":"Reduced basis method based on a posteriori error estimate for the parameterized Allen-Cahn equation","authors":"Liang Wu ,&nbsp;Mejdi Azaïez ,&nbsp;Tomás Chacón Rebollo ,&nbsp;Chuanju Xu","doi":"10.1016/j.jcp.2025.114278","DOIUrl":"10.1016/j.jcp.2025.114278","url":null,"abstract":"<div><div>In this paper we propose an efficient and accurate reduced-order method for the parameterized Allen-Cahn equation. The proposed method aims to construct efficient low-dimensional reduced basis to approximate the Allen-Cahn equation with desired accuracy for all parameters of interest. The key is to select minimal parameters for which the snapshots are collected to generate the reduced basis. The selection of these parameters is guided by a residual estimator. To this end, we first derive a posteriori error estimates for this residual estimator. Then, we propose a POD-greedy algorithm based on the derived a posteriori error estimates to construct the efficient reduced basis. The established a posteriori error estimate and the accuracy of the proposed reduced-order method are verified through several numerical examples. Specifically, our numerical experiments show that the obtained a posteriori error estimate is sharp and that the convergence of the error with respect to the POD-greedy iteration is exponential. In addition, the efficiency of the POD-greedy sampling procedure is demonstrated by some practical examples.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"540 ","pages":"Article 114278"},"PeriodicalIF":3.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829337","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":"Semi-implicit relaxed finite volume schemes for hyperbolic multi-scale systems of conservation laws","authors":"Andrea Thomann","doi":"10.1016/j.jcp.2025.114263","DOIUrl":"10.1016/j.jcp.2025.114263","url":null,"abstract":"<div><div>In this paper a new semi-implicit relaxation scheme for the simulation of multi-scale hyperbolic conservation laws based on a Jin-Xin relaxation approach is presented. It is based on the splitting of the flux function into two or more subsystems separating the different scales of the considered model whose stiff components are relaxed thus yielding a linear structure of the resulting relaxation model on the relaxation variables. This allows the construction of a linearly implicit numerical scheme, where convective processes are discretized explicitly. Thanks to this linearity, the discrete scheme can be reformulated in linear decoupled wave-type equations resulting in the same number of evolved variables as in the original system. To obtain a scale independent numerical diffusion, centred fluxes are applied on the implicitly treated terms, whereas classical upwind schemes are applied on the explicit parts. The numerical scheme is validated by applying it on the Toro &amp; Vázquez-Cendón (2012) splitting of the Euler equations and the Fambri (2021) splitting of the ideal MHD equations where the flux is split in two, respectively three sub-systems. The performance of the numerical scheme is assessed running benchmark test-cases from the literature in one and two spatial dimensions.</div></div>","PeriodicalId":352,"journal":{"name":"Journal of Computational Physics","volume":"539 ","pages":"Article 114263"},"PeriodicalIF":3.8,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780471","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}