International Journal for Numerical Methods in Fluids最新文献

{"title":"Development of New Free Surface Methods for a Fixed-Grid Fully Nonlinear Potential Flow Solver Using the Immersed Boundary Method","authors":"Fabian Knoblauch,&nbsp;Widar Wang,&nbsp;Hans Bihs","doi":"10.1002/fld.70073","DOIUrl":"https://doi.org/10.1002/fld.70073","url":null,"abstract":"<div>\u0000 \u0000 <p>Fully nonlinear wave-structure interaction in real sea states is complex to simulate, though important for load estimations. While Navier–Stokes equation-based CFD solvers have proven to be capable of modelling these physics, their computational costs are often a limiting factor for their applicability. An alternative is given by FDM-based fully nonlinear potential flow solvers, which have been under constant development in the recent years and have proven to be capable of simulating irregular nonlinear real sea states at a fraction of the computational costs needed by CFD. Most of the current fully nonlinear potential flow solvers are utilising a <span></span><math>\u0000 <mrow>\u0000 <mi>σ</mi>\u0000 </mrow></math>-grid domain to represent the unsteady free surface boundary, which significantly hinders the representation of structures inside the domain. In the presented work, a fixed-grid potential flow solver utilising parallel computation on a multi-core infrastructure is developed to allow for the implementation of structures directly in the domain. Therefore, new methods for enforcing the free surface boundary conditions inside the fixed-grid domain are derived. Different approaches are introduced and tested to determine the most accurate one. The presented work thereby puts emphasis on building a fixed-grid solver that can model complex wave transformations, as well as irregular real sea states in time domain with an accuracy on par with a <span></span><math>\u0000 <mrow>\u0000 <mi>σ</mi>\u0000 </mrow></math>-grid solver, while not limiting its flexibility with a <span></span><math>\u0000 <mrow>\u0000 <mi>σ</mi>\u0000 </mrow></math>-grid. The presented solver's accuracy is tested for various two- and three-dimensional nonlinear wave propagation and transformation cases by comparing to nonlinear wave theory and experimental results. The results show that the solver is capable of modelling real sea states and nonlinear wave transformation and that it is of comparable accuracy to fully nonlinear potential flow solvers utilising a <span></span><math>\u0000 <mrow>\u0000 <mi>σ</mi>\u0000 </mrow></math>-grid.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 8","pages":"890-921"},"PeriodicalIF":2.1,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148386633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast Calculation for the Flow and Heat Transfer of Tempered Fractional Maxwell Viscoelastic Fluid","authors":"Yi Liu,&nbsp;Mochen Jiang,&nbsp;Libo Feng","doi":"10.1002/fld.70076","DOIUrl":"https://doi.org/10.1002/fld.70076","url":null,"abstract":"<p>This work presents an investigation into the unsteady thermal flow behavior of a tempered fractional Maxwell viscoelastic fluid over a moving plate. To accurately characterize the fluid behavior, the classical Maxwell constitutive relation is extended by incorporating a tempered fractional derivative, which is shown to be both physically meaningful and significant in capturing the viscoelastic properties of the fluid. The newly developed fractional Maxwell constitutive model is incorporated into both the momentum equation and the energy equation, forming a coupled system that describes the fluid dynamics and heat transfer. To numerically solve this tempered fractional coupled model, we employ the <span></span><math>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 <mn>1</mn>\u0000 </mrow></math> scheme with the finite difference method. However, due to the high computational cost associated with small time steps, we propose an efficient fast algorithm based on the sum-of-exponential (SOE) approximation to significantly reduce computation time. To verify the efficiency of the numerical scheme and fast algorithm, a specific example is examined. Furthermore, we analyze the influence of key parameters on fluid motion and thermal characteristics, offering deeper insights into the system's behavior. The study demonstrates that the tempered fractional coupled model is a viable and efficient tool to model flow and heat transfer in Maxwell fluids, offering valuable contributions to the study of complex systems.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 8","pages":"969-979"},"PeriodicalIF":2.1,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.70076","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148386900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Analysis of the Effects of Stepped-Ramp Aerospikes on Aerodynamic Drag and Heating on a Blunt Body","authors":"Adithya Vijay,&nbsp;Lisa Francis Dsouza,&nbsp;Pranay Agrawal,&nbsp;Anurag Kumar Jha,&nbsp;Narender Singh,&nbsp;Rajesh Kumar Saluja,&nbsp;Manish Naagar,&nbsp;Neeraj Kumar Gahlot","doi":"10.1002/fld.70075","DOIUrl":"https://doi.org/10.1002/fld.70075","url":null,"abstract":"<div>\u0000 \u0000 <p>Mitigating aerodynamic heating while reducing drag is a critical challenge in the development of high-speed vehicles. A modified aerospike (MAS) configuration integrating a flat spike with stepped-ramp geometries is proposed to improve the aerodynamic performance of blunt-nosed bodies. Two-dimensional axisymmetric simulations were performed by solving the Reynolds-averaged Navier–Stokes (RANS) equations with the SST <i>k</i>–<i>ω</i> turbulence model at Mach 2.23, zero angle of attack, static pressure of 28,554.2 Pa, and free stream temperature of 300 K. Grid independence and validation against available experimental and computational results established the reliability of the numerical framework. Comparative analysis revealed that stepped-ramp aerospikes significantly outperformed conventional aerospike designs. The three-stepped configuration (MAS1) achieved a drag reduction of approximately 39%, while the four-stepped configuration (MAS2) provided the maximum reduction of nearly 47% relative to the baseline blunt body and up to 30% compared to a conventional aerospike. Thermal analysis showed a marked decrease in surface heat flux on the aft section, enhancing thermal protection and reducing material degradation risks. The results demonstrate that stepped-ramp aerospikes effectively control shock–boundary layer interactions, reduce both pressure drag and aerodynamic heating, and offer a promising solution for integration into next generation supersonic vehicle designs.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 8","pages":"955-968"},"PeriodicalIF":2.1,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148386918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 Microscopic Remaining Oil Prediction Method in Chemical Flooding Based on Parameter Constraints","authors":"Bei Wei,&nbsp;Yang Zhang,&nbsp;Dong Zhao,&nbsp;Qingjun Du,&nbsp;Jian Hou","doi":"10.1002/fld.70074","DOIUrl":"https://doi.org/10.1002/fld.70074","url":null,"abstract":"<div>\u0000 \u0000 <p>Predicting the microscopic distribution of remaining oil in chemical flooding is challenging due to the complex interplay of wettability, interfacial tension, and flow dynamics. Existing data-driven models often require extensive training data and lack physical consistency. To address this, we propose a physical-constrained deep learning framework for rapid and accurate prediction. Initially, a comprehensive dataset was generated using the lattice Boltzmann method, encompassing variations in wettability, interfacial tension, displacement velocity, and viscosity ratio. A regression model was derived to quantify the relationship between these parameters and the remaining oil characteristic. We then developed a hybrid loss function combining Dice loss with a physics-based regression loss. The network structure was established based on the U-Net structure and a normalization network. Then, the network underwent training with various loss functions and datasets. Finally, the method predicted the microscopic remaining oil under various conditions and classified the remaining oil to examine the change patterns. The prediction results were compared with and without constraints in the loss function, revealing that this method significantly reduces dataset establishment time and data volume required. Additionally, favorable findings were obtained even with displacement conditions not included in the training set. Prediction analysis under various conditions showed that a closer oil-wet rock ratio to water-wet rock ratio results in more network remaining oil and less cluster remaining oil. Higher displacement velocities or lower interfacial tensions correlate with a reduced proportion of network remaining oil. This study aids in swiftly analyzing the microremaining oil alterations in chemical flooding under different conditions and provides a foundation for further exploration of remaining oil postchemical flooding.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 8","pages":"922-938"},"PeriodicalIF":2.1,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148386393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Local Polynomial Regression and Filtering for a Versatile Mesh-Free PDE Solver","authors":"Alberto M. Gambaruto","doi":"10.1002/fld.70069","DOIUrl":"https://doi.org/10.1002/fld.70069","url":null,"abstract":"<p>A high-order, mesh-free finite difference method for solving partial differential equations is presented. The spatial domain is sampled by an irregular point cloud, and at each point, a local polynomial approximation is formulated. This polynomial is used to approximate both the function and its derivatives. The function approximation is used as a filter to regularise the solution and ensure stability of the method. The local polynomial is obtained by straightforward least squares minimisation, which is solved by using the singular value decomposition method, with truncation. A non-parametric regression with robust M-estimator functions is also investigated and exhibits additional robustness and accuracy. A straightforward semi-discrete form is obtained by adopting an explicit time discretisation, and combined with the local polynomial regression, a modular assembly of complete solver algorithms is possible. The resulting numerical method is accurate, simple and versatile. Challenging numerical benchmark tests are investigated, namely the solution to inviscid Burgers' equation, linearised Euler equations and incompressible Navier-Stokes equations (with the artificial compressibility and vorticity transport formulations) in Eulerian and Lagrangian reference frames.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 7","pages":"804-839"},"PeriodicalIF":1.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.70069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148116056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Error Estimates for Velocity-Pseudo-Stress Formulation Applied to the Generalized Oseen Problem","authors":"Tomás P. Barrios,&nbsp;J. Manuel Cascón,&nbsp;María González","doi":"10.1002/fld.70070","DOIUrl":"https://doi.org/10.1002/fld.70070","url":null,"abstract":"<div>\u0000 \u0000 <p>We consider a dual-mixed method for the generalized Oseen equations, where the velocity and pseudo-stress are treated as the primary unknowns. A stabilized discrete scheme is obtained by augmenting the dual-mixed approach with suitable least-squares terms derived from the physical equations. We prove that the scheme is well-posed using the Lax-Milgram Lemma. To approximate the unknowns, we propose using continuous piecewise polynomials for the velocity field and Raviart Thomas elements for each row of the pseudo-stress. We prove optimal a priori error estimates for this choice. We also provide a residual-based a posteriori error analysis. We derive a simple a posteriori error indicator and prove it is reliable and locally efficient. Finally, we supply some numerical experiments that confirm the theoretical results.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 7","pages":"840-856"},"PeriodicalIF":1.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148120015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wave Energy Characteristics and Dissipation in a Wave Tank Under Shake Plate Mode","authors":"Weiqi Zhang,&nbsp;Derong Duan,&nbsp;Xiangyang Lin,&nbsp;Changqing Gao,&nbsp;Hui Zhang,&nbsp;Xuefeng Yang","doi":"10.1002/fld.70068","DOIUrl":"https://doi.org/10.1002/fld.70068","url":null,"abstract":"<div>\u0000 \u0000 <p>In recent years, there has been an increasing interest in understanding the properties of wave energy, including its propagation and dissipation. This study established a numerical wave tank using VOF method to simulate real-time wave-making motion under rocking plate mode and investigated wave energy characteristics and dissipation in the wave propagation. The waveform data and wave spectrum model were obtained and verified with experimental data. Results indicated that the numerical results were good in agreement with the experimental data. The speed, amplitude, circular frequency, and water depth of the shake plate motion significantly affect wave propagation and wave energy characteristics; different wavelengths have different effects on wave energy attenuation, and wave nonlinear characteristics affect the characteristics and dissipation of wave energy. The results of this study can provide reference for marine engineering design and marine environmental protection.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 7","pages":"785-803"},"PeriodicalIF":1.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148106032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance Assessment of the Immersed Boundary Method in the Framework of the Moment Representation Lattice Boltzmann Method","authors":"Marco A. Ferrari,&nbsp;Ricardo de Souza,&nbsp;Admilson T. Franco","doi":"10.1002/fld.70071","DOIUrl":"https://doi.org/10.1002/fld.70071","url":null,"abstract":"<p>This study implements the immersed boundary method (IBM) coupled with the moment representation lattice Boltzmann method (MR-LBM) for simulating fluid–structure interactions. Due to the nature of the MR-LBM framework, which only stores moments, it is possible to eliminate some steps of the coupling with IBM compared to traditional LBM methods that store populations. As a result, the performance improves, and memory bandwidth requirements are reduced, a crucial factor in GPU implementations. We present results demonstrating the impact of parameters such as node spacing, kernel size, and node distribution on the computational speed of the method. Analyzing these metrics enables the assessment of which parts of the method impact performance and, therefore, should be targeted for future development.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 7","pages":"857-870"},"PeriodicalIF":1.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.70071","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148123163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Local Polynomial Regression and Filtering for a Versatile Mesh-Free PDE Solver","authors":"Alberto M. Gambaruto","doi":"10.1002/fld.70069","DOIUrl":"https://doi.org/10.1002/fld.70069","url":null,"abstract":"<p>A high-order, mesh-free finite difference method for solving partial differential equations is presented. The spatial domain is sampled by an irregular point cloud, and at each point, a local polynomial approximation is formulated. This polynomial is used to approximate both the function and its derivatives. The function approximation is used as a filter to regularise the solution and ensure stability of the method. The local polynomial is obtained by straightforward least squares minimisation, which is solved by using the singular value decomposition method, with truncation. A non-parametric regression with robust M-estimator functions is also investigated and exhibits additional robustness and accuracy. A straightforward semi-discrete form is obtained by adopting an explicit time discretisation, and combined with the local polynomial regression, a modular assembly of complete solver algorithms is possible. The resulting numerical method is accurate, simple and versatile. Challenging numerical benchmark tests are investigated, namely the solution to inviscid Burgers' equation, linearised Euler equations and incompressible Navier-Stokes equations (with the artificial compressibility and vorticity transport formulations) in Eulerian and Lagrangian reference frames.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 7","pages":"804-839"},"PeriodicalIF":1.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.70069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148116055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Error Estimates for Velocity-Pseudo-Stress Formulation Applied to the Generalized Oseen Problem","authors":"Tomás P. Barrios,&nbsp;J. Manuel Cascón,&nbsp;María González","doi":"10.1002/fld.70070","DOIUrl":"https://doi.org/10.1002/fld.70070","url":null,"abstract":"<div>\u0000 \u0000 <p>We consider a dual-mixed method for the generalized Oseen equations, where the velocity and pseudo-stress are treated as the primary unknowns. A stabilized discrete scheme is obtained by augmenting the dual-mixed approach with suitable least-squares terms derived from the physical equations. We prove that the scheme is well-posed using the Lax-Milgram Lemma. To approximate the unknowns, we propose using continuous piecewise polynomials for the velocity field and Raviart Thomas elements for each row of the pseudo-stress. We prove optimal a priori error estimates for this choice. We also provide a residual-based a posteriori error analysis. We derive a simple a posteriori error indicator and prove it is reliable and locally efficient. Finally, we supply some numerical experiments that confirm the theoretical results.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"98 7","pages":"840-856"},"PeriodicalIF":1.8,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148120302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}