Computers & Fluids最新文献

{"title":"A 3D numerical strategy for the computations of shock-induced bubble collapse near a wall","authors":"Ksenia Kozhanova ,&nbsp;Yannick Hoarau ,&nbsp;Eric Goncalves da Silva","doi":"10.1016/j.compfluid.2025.106609","DOIUrl":"10.1016/j.compfluid.2025.106609","url":null,"abstract":"<div><div>The importance of modelling two-phase flows involving shock waves arises from many engineering and medical applications. The presence of strong shock waves and their interactions with bubble interfaces, the high density ratio between phases and the large variation of material properties makes the resolution of such problems a complicated task for the numerical methods. While the variety of numerical techniques to solve these problems exist, e.g. the sharp interface or the diffuse interface methods, these strategies can lead to spurious oscillations of the solution near the interface. It is well known that it is difficult to achieve both a high order accuracy of the scheme and the monotonicity of the solution. In this paper a four-equation two-phase model is employed and integrated in an explicit fully parallelised finite-volume solver with HLLC numerical scheme coupled with WENO reconstruction methods and Hancock predictor–corrector scheme and non-uniform mesh based on stretching function in order to compute a 3D shock-induced bubble collapse near a wall. The novelty of our work is improved accuracy of computations of such a problem with optimised computational cost thanks to the non-uniform mesh introduction in 3D computations.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"293 ","pages":"Article 106609"},"PeriodicalIF":2.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746651","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":"Multi-fidelity modeling of net power savings of an actuated turbulent boundary layer","authors":"P. Olivucci ,&nbsp;X. Shao ,&nbsp;M. Albers ,&nbsp;W. Schröder ,&nbsp;R. Semaan","doi":"10.1016/j.compfluid.2025.106608","DOIUrl":"10.1016/j.compfluid.2025.106608","url":null,"abstract":"<div><div>We simulate and model the net power savings of an actuated turbulent boundary layer flow. The actuation is performed by spanwise traveling transverse surface waves parametrized by wavelength, amplitude, and period. The data is provided by 81 large-eddy simulations (LES) over a range of conditions. Since the numerical resolution of the skin-friction physics requires expensive large-eddy simulations, additional input power data is provided by low-cost, low-fidelity, two-dimensional simulations. An ad-hoc Gaussian Process (GP) framework is used to construct a single and a multi-fidelity surrogate model of the net power savings response to a range of actuation settings. The multi-fidelity model is shown to be able to leverage the two databases and combine the two independent constitutive models for the drag reduction and the input power. The predictive performance of the model is evaluated and compared to the single-fidelity baseline through cross-validated accuracy scores, including its probabilistic predictions. The models are queried to infer the detailed dependence of the flow response on the control parameters, to explore the existence of maxima, and to discuss the physical underpinnings of the flow.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"293 ","pages":"Article 106608"},"PeriodicalIF":2.5,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725253","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":"Zonal and adaptive mesh refinement for RANS-based transition models in FUN3D","authors":"Nathaniel Hildebrand ,&nbsp;Meelan M. Choudhari ,&nbsp;Preethi V. Mysore ,&nbsp;Balaji S. Venkatachari ,&nbsp;Pedro Paredes","doi":"10.1016/j.compfluid.2025.106607","DOIUrl":"10.1016/j.compfluid.2025.106607","url":null,"abstract":"<div><div>We determine how the grid resolution and topology influence the accuracy and convergence of RANS-based transition model results by analyzing the NLF-0416 and NLR-7301 airfoils at subsonic and transonic Mach numbers, respectively. Natural and separation-induced transition scenarios are analyzed using the Langtry-Menter <span><math><mi>γ</mi></math></span>-<span><math><msub><mrow><mi>Re</mi></mrow><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mi>t</mi></mrow></msub></mrow></msub></math></span> model. Multiple grid refinement techniques are investigated. First, we determine the relative effectiveness of zonal streamwise refinement near transition to turbulence for structured grids as an alternative to costly global uniform refinement. We also complement this zonal technique by globally varying the wall-normal resolution keeping the streamwise resolution fixed. The zonal streamwise refinement can accurately model separation-induced transition, but significant wall-normal resolution is needed to model natural transition that occurs on airfoils. A series of unstructured prismatic grids that have similar node counts and viscous wall spacings as the structured hexahedral grids result in solutions that are only about 1% different in terms of the lift and drag coefficients at infinite resolution according to Richardson extrapolation. We employ Mach-Hessian-based unstructured grid adaptation to natural and separation-induced transition on the NLF-0416 airfoil, which leads to both the lift and drag coefficients plateauing on coarse grids, but the converged transition locations can be inaccurate due to poor near-wall resolution. Adjoint-based grid adaptation is explored briefly, and for imposed transition with the Spalart–Allmaras model, it yields accurate solutions even for coarse grid resolutions.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"293 ","pages":"Article 106607"},"PeriodicalIF":2.5,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705011","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":"Unified algorithm to efficiently implement high-order schemes of differential form on unstructured grids","authors":"Jiaxian Qin ,&nbsp;Yaming Chen ,&nbsp;Xiaogang Deng","doi":"10.1016/j.compfluid.2025.106605","DOIUrl":"10.1016/j.compfluid.2025.106605","url":null,"abstract":"<div><div>It is well recognized that structured grid methods have the advantage of significantly lower computational cost needed for achieving higher accuracy, and unstructured grid methods are welcomed for their convenience in grid generation. Nevertheless, the major obstacle hindering the practical application of structured grid methods to complex engineering problems is the generation of high-quality grids, whereas the bottleneck for high-order unstructured grid methods lies in their huge demand for computational resource and memory. In this work, we propose a novel algorithm which enables the efficient implementation of high-order schemes of differential form on unstructured grids. By dividing the initial simplex cells locally into quadrilateral or hexahedral sub-cells, unique line-structures called Hamiltonian path can be identified. Subsequently, high-order spacial discretization can be done in a dimension-by-dimension manner along the lines, inheriting the accuracy and efficiency of structured grid methods. Meanwhile, the line-structures make the application of robust line-implicit time-marching schemes on fully unstructured grid possible, leading to excellent efficiency and robustness.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"293 ","pages":"Article 106605"},"PeriodicalIF":2.5,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681860","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":"An enhanced analytical-based geometry processor for the volume of solid (VoS) method in CPU and GPU computations","authors":"Fandi D. Suprianto ,&nbsp;Ming-Jyh Chern ,&nbsp;Chin-Cheng Wang","doi":"10.1016/j.compfluid.2025.106602","DOIUrl":"10.1016/j.compfluid.2025.106602","url":null,"abstract":"<div><div>This paper introduces an analytical–based geometry processor which improves the efficiency of volume-of-solid (VoS) CFD solvers for fluid–structure interaction (FSI) scenarios with rigid body motion. The combination of the VoS method and the direct forcing immersed boundary (DFIB) method speeds up geometry creation while significantly reducing computational workload during unsteady simulations of solid structure movement or deformation. The proposed geometry processor’s effectiveness is demonstrated in the vortex-induced vibrations (VIV) scenario of a single circular cylinder, where the geometry was dynamically modified at each timestep to correspond to the cylinder’s passive motion. Comparisson studies show that the enhanced VoS function accelerates geometry construction process significantly faster than the ray-casting method while maintaining the same level of accuracy. Furthermore, its GPU implementation consistently achieves significant speedup across various computational loads, indicating superior scalability. This proposed method not only works well for simple geometries, but it also supports a wide range of multi-body curvilinear forms, including extruded spans and fully defined 3D geometries, making it suitable for a variety of applications.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"293 ","pages":"Article 106602"},"PeriodicalIF":2.5,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705012","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":"Dual scale Residual-Network for turbulent flow sub grid scale resolving: A prior analysis","authors":"Omar Sallam,&nbsp;Mirjam Fürth","doi":"10.1016/j.compfluid.2025.106592","DOIUrl":"10.1016/j.compfluid.2025.106592","url":null,"abstract":"<div><div>This paper introduces generative Residual Networks (ResNet) as a surrogate Machine Learning (ML) tool for Large Eddy Simulation (LES) Sub Grid Scale (SGS) resolving. The study investigates the impact of incorporating Dual Scale Residual Blocks (DS-RB) within the ResNet architecture. Two LES SGS resolving models are proposed and tested for prior analysis test cases: a super-resolution model (SR-ResNet) and a SGS stress tensor inference model (SGS-ResNet). The SR-ResNet model task is to upscale LES solutions from coarse to finer grids by inferring unresolved SGS velocity fluctuations, exhibiting success in preserving high-frequency velocity fluctuation information, and aligning with higher-resolution LES solutions’ energy spectrum. Furthermore, employing DS-RB enhances prediction accuracy and precision of high-frequency velocity fields compared to Single Scale Residual Blocks (SS-RB), evident in both spatial and spectral domains. The SR-ResNet model is tested and trained on filtered/downsampled 2-D LES planar jet injection problems at two Reynolds numbers, two jet configurations, and two upscale ratios. In the case of SGS stress tensor inference, both SS-RB and DS-RB exhibit higher prediction accuracy compared to other explicit closure models such as the Smagorinsky model or the Approximate Deconvolution Model (ADM) with reference to the true DNS SGS stress tensor, with DS-RB-based SGS-ResNet showing stronger statistical alignment with DNS data. The SGS-ResNet model is tested on a filtered/downsampled 2-D DNS isotropic homogeneous decay turbulence problem. The adoption of DS-RB incurs notable increases in network size, training time, and forward inference time, with the network size expanding by over tenfold, and training and forward inference times increasing by approximately 0.5 and 3 times, respectively.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"292 ","pages":"Article 106592"},"PeriodicalIF":2.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643968","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 lattice Boltzmann flux solver for numerical simulation of flows with the viscoelastic fluid","authors":"Hua Zhang ,&nbsp;Chang Shu ,&nbsp;Lian-Ping Wang ,&nbsp;Yaguang Liu ,&nbsp;Lailai Zhu","doi":"10.1016/j.compfluid.2025.106593","DOIUrl":"10.1016/j.compfluid.2025.106593","url":null,"abstract":"<div><div>In this paper, a viscoelastic lattice Boltzmann flux solver (VLBFS) is developed to simulate incompressible flows of viscoelastic fluids with linear and non-linear constitutive models. In this method, the macroscopic equations are solved by the finite volume method, where the fluxes at the cell interface are evaluated by local reconstruction of the solutions of lattice Boltzmann equations (LBE). Two sets of distribution functions are introduced to reconstruct the cell-interface fluxes, one used for mass and momentum fluxes and the other for the conformation tensor flux in the polymer constitutive equation. The elastic-viscous stress splitting (EVSS) and the solvent-polymer stress splitting (SPSS) techniques are incorporated into the present LBFS to improve the numerical stability. The standard lattice Boltzmann method (LBM) for solving the polymer constitutive equation contains redundant diffusion terms, but this problem is resolved in the current LBFS by setting the relaxation time corresponding to the true diffusion-free limit thus the correct polymer constitutive equation can be recovered. Furthermore, VLBFS eliminates other disadvantages of the standard LBM, such as the LBM on-grid advection coupling the time interval with grid spacing, complicated treatment of the mesoscopic boundary conditions, dependence on uniform grids, and the larger memory requirement due to solving the phase-space discrete distributions. Several flows of a viscoelastic fluid, namely, the two-dimensional plane Poiseuille flow, two-dimensional simplified four-roll mill flows, and three-dimensional Taylor–Green vortex flows, are considered to investigate the accuracy and stability of the present method. The results are found to be in good agreement with the analytical solutions and the previous numerical results. Numerical error analyses show that the present method owns a second-order accuracy in space. The developed VLBFS extends the application domain of LBFS and serves as a basis for simulating viscoelastic flows at high Weissenberg numbers.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"292 ","pages":"Article 106593"},"PeriodicalIF":2.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643967","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":"Development of new wall functions for RANS model in superhydrophobic surface based on CFD and data-driven uncertainty quantification","authors":"Hoai-Thanh Nguyen ,&nbsp;Byeong-Cheon Kim ,&nbsp;Sang-Wook Lee ,&nbsp;Jaiyoung Ryu ,&nbsp;Minjae Kim ,&nbsp;Jaemoon Yoon ,&nbsp;Kyoungsik Chang","doi":"10.1016/j.compfluid.2025.106603","DOIUrl":"10.1016/j.compfluid.2025.106603","url":null,"abstract":"<div><div>This study investigates turbulent channel flow over superhydrophobic surfaces using direct numerical simulation and <em>k-</em><span><math><mrow><mi>ε</mi></mrow></math></span> turbulence model with a newly developed wall function. A surrogate model, constructed using Gaussian Process Regression, predicts slip velocity and shifted velocity based on SHS texture parameters, specifically texture spacing and solid fraction. Direct numerical simulation conducted at a friction Reynolds number of <span><math><mrow><mi>R</mi><msub><mi>e</mi><mi>τ</mi></msub><mo>=</mo><mn>180</mn></mrow></math></span>, reveal strong linear relationships between slip velocity and shifted velocity . The surrogate model is validated against existing direct numerical simulation data, demonstrating high accuracy with an R-squared value of 0.957 and minimal prediction error. This surrogate model to predict the slip velocity is incorporated into a modified wall function for the <em>k-</em><span><math><mrow><mi>ε</mi></mrow></math></span> turbulence model, which is implemented and tested using the open source software OpenFOAM. The proposed wall function yields results that align well with direct numerical simulation predictions in the near wall region, while some discrepancies occur in the log-layer due to the fundamental differences between direct numerical simulation and Reynolds-averaged Navier-Stokes methodologies. Despite these differences, the new wall function provides an efficient approach for simulating superhydrophobic surface channel flows using Reynolds-averaged Navier-Stokes models, reducing computational costs while maintaining acceptable accuracy. This research establishes a robust framework for integrating superhydrophobic surface effects into turbulence modelling, enhancing predictive capabilities for complex engineering applications.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"292 ","pages":"Article 106603"},"PeriodicalIF":2.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680025","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":"3D mesh regularization within an ALE code using a weighted line sweeping method","authors":"Jérôme Breil ,&nbsp;Guillaume Damour ,&nbsp;Sébastien Guisset ,&nbsp;Arnaud Colaïtis","doi":"10.1016/j.compfluid.2025.106591","DOIUrl":"10.1016/j.compfluid.2025.106591","url":null,"abstract":"<div><div>The Lagrangian formalism is widely used to simulate hydrodynamic responses in complex engineering applications, particularly those involving strong shock waves. However, as the mesh moves with the fluid, it can become highly distorted, requiring a regularization step. This involves constructing a new grid and remapping conservative quantities onto it to restore mesh quality. This work introduces a regularization method for block-structured meshes within a 3D ALE (Arbitrary Lagrangian–Eulerian) code. The proposed approach prevents mesh tangling while preserving the anisotropic features of the initial Lagrangian mesh. This regularization technique incorporates aspect ratio-based weights to control mesh smoothing. Unlike uniform rezoning techniques, this weighted approach maintains proximity to the Lagrangian mesh while improving mesh quality. The method effectively handles concave geometries by mitigating the grid attraction phenomenon, which typically leads to mesh concentration along concave edges. Numerical experiments demonstrate its efficiency in regularizing severely deformed meshes, and its integration within the ALE framework is validated on challenging hydrodynamic test cases, including the triple point problem.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"292 ","pages":"Article 106591"},"PeriodicalIF":2.5,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143591446","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":"Advanced numerical methods for conjugate heat transfer problems","authors":"Marc-Paul Errera","doi":"10.1016/j.compfluid.2025.106594","DOIUrl":"10.1016/j.compfluid.2025.106594","url":null,"abstract":"<div><div>Conjugate heat transfer (CHT) analysis is a simulation process that addresses the thermal interaction between a solid body and a fluid. It is a crucial aspect in a wide range of engineering applications, especially in the aerospace industry. This paper focuses on implementing adaptive coupling coefficients to optimize CHT by improving stability and simplicity. A mathematical model based on a normal mode stability analysis is employed. This study highlights the importance of a new dimensionless number, the \"numerical Biot number\", and explores adaptive coupling coefficients in three distinct aerothermal situations: steady coupling, steady coupling with radiation, and unsteady coupling. The main results of these three cases are compared, illustrated, and analyzed. The results demonstrate the potential of the theoretical approach, particularly in understanding the impact of different phenomena on the stability process and the challenges of convergence in certain conditions.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"292 ","pages":"Article 106594"},"PeriodicalIF":2.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143591447","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}