Computers & Fluids最新文献

{"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 dynamic immersed boundary method for simulating an adaptive nozzle generating discrete wind gusts","authors":"K. Boulbrachene,&nbsp;M. Breuer","doi":"10.1016/j.compfluid.2025.106775","DOIUrl":"10.1016/j.compfluid.2025.106775","url":null,"abstract":"<div><div>The recently developed wind gust generator, the <em>adaptive nozzle</em> (Wood and Breuer, 2025) , features a nozzle with a fully rotatable upper contour, enabling a smooth gust generation with low unwanted flow disturbances. While preserving the underlying gust-generation principle of its predecessor, the new design significantly reduces pressure losses caused by flow blockage and preserves the original horizontal trajectory of the flow along the streamwise direction. While experiments have validated the improved design, a comprehensive numerical analysis is crucial to resolve the three-dimensional flow fields across the entire computational domain. This shall also facilitate capturing the resulting transient aerodynamic loads on a wind tunnel specimen — quantities difficult to measure experimentally. To accurately capture the complex flow dynamics, high-fidelity large-eddy simulations are conducted, modeling the nozzle’s upper contour as a dynamic immersed boundary (IB). A curvilinear Eulerian grid is employed to ensure both efficient and precise spatial resolution of the problem. The moving least-squares (MLS) version of the direct forcing IB approach (Vanella and Balaras, 2009) is used to construct an IB kernel for each Lagrangian marker. Additionally, the MLS approach is also applied to construct one-sided kernel functions for Lagrangian points near the boundaries of the computational domain. Challenges related to the efficient IB simulation on curvilinear grids are addressed, and a solution is proposed within the MLS framework. The predicted results are analyzed in detail and validated against the experimental data by Wood and Breuer (2025) , providing insights into the effectiveness of the new design in generating controlled wind gusts.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106775"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829072","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}

{"title":"Large eddy simulation of fuel/air co-flow jet mixing enhancement in supersonic crossflow","authors":"Xin Li,&nbsp;Yu Pan,&nbsp;Chaoyang Liu,&nbsp;Junbo Zou","doi":"10.1016/j.compfluid.2025.106781","DOIUrl":"10.1016/j.compfluid.2025.106781","url":null,"abstract":"<div><div>Efficient mixing is critical for combustion organization in a high Mach number flows, and fuel/air co-flow jets continue to gain attention as a potential injection scheme. To further investigate the flow and mixing characteristics of co-flow transverse jets in a supersonic crossflow, high-fidelity Large Eddy Simulations are conducted by implementing a low numerical dissipation scheme. The reliability of the numerical method is confirmed by comparison with the experimental data. Then the effects of central air jet pressure, annular fuel jet pressure, and central jet activation/deactivation on the mixing process are systematically analyzed. Current research indicates that increasing central air jet pressure suppresses velocity fluctuations in the windward shear layer, while raising annular fuel jet pressure enhances mixing in this region. Deactivating the central jet introduces an additional recirculation zone, weakens jet penetration, reduces the leeward recirculation zone, and concentrates turbulent kinetic energy in the jet shear layer and wake. Mixing efficiency analysis shows that increasing central jet pressure or deactivating the central jet elevates downstream mixing efficiency to approximately 45 %, which is significantly better than the annular fuel jet pressurization scheme. Vortex dynamics investigation demonstrates that higher annular fuel jet pressure increases the average vorticity peak. The baroclinic term and the compressible dilatational stretching term show a bidirectional adjustment effect on the shear layer/wake region. Increased central jet pressure introduces supplementary air, raising the viscous term contribution to 48 % and significantly inhibiting vorticity growth. Furthermore, the vorticity stretching term and compressible dilatational stretching term dominate the vorticity generation and transport processes. This study provides theoretical foundations for enhancing the mixing performance of co-flow jet configurations.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106781"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809705","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":"Efficient implementation of the Allen–Cahn phase-field method for material interface tracking","authors":"Sergio Pirozzoli ,&nbsp;Simone Di Giorgio ,&nbsp;Daniele Rossi","doi":"10.1016/j.compfluid.2025.106768","DOIUrl":"10.1016/j.compfluid.2025.106768","url":null,"abstract":"<div><div>We consider a modified version of the conservative Allen–Cahn phase-field method for tracking material interfaces. By removing the diffusive term and discretizing the advective terms with a first-order upwind scheme, we achieve a substantial reduction in numerical diffusion, resulting in sharper interfaces for a given compression parameter. The resulting scheme is monotone, leading to key numerical properties such as boundedness and convergence to weak entropy solutions. Notably, the new method permits a significantly larger time step compared to standard implementations, especially in multiple spatial dimensions. Numerical tests support these theoretical findings and demonstrate effectiveness and robustness of the new algorithm across a range of multiphase flow problems.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106768"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781758","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 Newton’s solver for high-order wall distance computation on three-dimensional curved, unstructured meshes","authors":"Ehsan Mirzaee ,&nbsp;Carl Ollivier-Gooch","doi":"10.1016/j.compfluid.2025.106765","DOIUrl":"10.1016/j.compfluid.2025.106765","url":null,"abstract":"<div><div>Accurate wall distance computation is essential in high-order turbulent flow simulations involving complex geometries. This paper presents a new higher-order approach to compute wall distance on three-dimensional, curved, unstructured meshes. The method uses Lagrange interpolation polynomials representing the mesh to formulate an optimization problem whose solution yields the wall distance. The domain is swept from the wall boundaries inward, and the optimization problem is solved for every vertex using Newton’s method. The algorithm is modified for domains with sharp edges, wall corners, or multiple wall boundaries. In problems with non-curved wall boundaries, the method finds the exact wall distance. For curved wall boundaries, when using cubic Lagrange polynomials for the mesh, the method achieves <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mi>h</mi></mrow><mrow><mn>4</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span> accuracy for the wall distance and <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mi>h</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span> accuracy for the normal-to-wall vector. Increasing the accuracy of the Lagrange functions used to define the mesh further improves the method’s order of accuracy.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106765"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809706","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":"Optimal jet flow control for suppressing three-dimensional vortex-induced motion in floating cylinders at subcritical Reynolds Numbers","authors":"Wulong Hu ,&nbsp;Haishan Xia ,&nbsp;Lei Li ,&nbsp;Zhonglan Tuo","doi":"10.1016/j.compfluid.2025.106784","DOIUrl":"10.1016/j.compfluid.2025.106784","url":null,"abstract":"<div><div>Controlling vortex-induced motion (VIM) is essential for improving the fatigue life of mooring systems in floating offshore platforms. This study proposes an active control strategy using a narrow-gap jet (width ratio 0.03 <em>D</em>) positioned at the wake of a three-dimensional floating cylinder at subcritical Reynolds numbers (<em>Re</em> = 4.4 × 10⁴). Through computational fluid dynamics (CFD) simulations based on the Improved Delayed Detached-Eddy Simulation (IDDES) method, the effects of jet velocity ratio (<em>IR</em> = <em>U_j</em>/<em>U</em>) and injection angle (<em>α</em>) on VIM suppression are systematically analyzed. Without jet flow, the cylinder exhibits significant lock-in resonance at a reduced velocity <em>U_r</em> = 7.6, with a lateral amplitude exceeding its diameter (<em>A_y</em> = 1.05 <em>D</em>). Introducing jet flow effectively suppresses VIM, achieving an 80% reduction in transverse amplitude (<em>A_y</em> = 0.26 <em>D</em>) at <em>α</em> = 45° and <em>IR</em> = 3. Optimal suppression occurs when the jet aligns with the flow separation zone (<em>α</em> = 45°∼67.5°), disrupting vortex coherence and delaying boundary layer separation. In contrast, jets perpendicular (<em>α</em> = 90°) or upstream-oriented (<em>α</em> = 135°) amplify low-frequency vortex merging, worsening oscillations. Spectral analysis reveals that a 0° jet reduces vortex shedding frequency by 30%, mitigating resonance, while high <em>IR</em> values (&gt; 3) at 45° shift energy to low-frequency ranges. The proposed slit-jet design demonstrates adaptability in multi-degree-of-freedom floating structures, offering a practical solution for enhancing offshore platform durability.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"301 ","pages":"Article 106784"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809618","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}