International Journal for Numerical Methods in Fluids最新文献

{"title":"An Inertia Correction Scheme for Hydrodynamic Lubrication Problems","authors":"Seyhan Ozen,&nbsp;C. Oktay Azeloglu","doi":"10.1002/fld.5379","DOIUrl":"https://doi.org/10.1002/fld.5379","url":null,"abstract":"<p>A new simplified numerical approach for accurately calculating the bearing pressure distribution in one-dimensional hydrodynamic lubrication problems, particularly including convective fluid inertia and film discontinuities, is presented. The method proposes a simple inertia correction scheme using a non-uniform finite difference method based on the Reynolds equation. Two possible approaches to estimating the pressure correction due to fluid inertia are discussed: the Bernoulli effect and the averaged inertia. The results obtained for various operating conditions, especially by employing the average fluid inertia method, are found to be almost identical to the full Navier–Stokes (CFD) results and are more generalized. The proposed method may provide extremely fast calculation with accuracy.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"830-839"},"PeriodicalIF":1.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.5379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786926","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":"An Implicit Scheme for Least-Square Gradient in Coupled Algorithm","authors":"Zhao-Ren Li,&nbsp;Guo-Hui Ou,&nbsp;Li Chen,&nbsp;Wen-Tao Ji,&nbsp;Wen-Quan Tao","doi":"10.1002/fld.5368","DOIUrl":"https://doi.org/10.1002/fld.5368","url":null,"abstract":"<div>\u0000 \u0000 <p>In this paper, an implicit scheme that uses the least-square method to compute the pressure gradient term in the momentum equation, mainly for coupled algorithm was proposed. Accurate computation of the pressure gradient is crucial in computational fluid dynamics, directly influencing the precision of calculation results. The least-square gradient can reach unconditional second-order accuracy in the finite volume method. Currently, the least-square gradient method is predominantly employed in segregated algorithms, primarily utilizing explicit schemes that are not applicable to coupled algorithms. The scarcity of high-accuracy schemes for computing pressure gradients in coupled algorithms underscores a significant research gap. It contributes by presenting a derivation of an implicit scheme for the least-square gradient, complemented by an extensive discussion on boundary treatment methods. The efficacy of proposed least-square method through comparative analysis involving the Green-Gauss method, as well as benchmarking against existing literature or analytical solutions across distinct cases. The findings demonstrate that, in the majority of cases, the least-square method offers superior accuracy and convergence rates compared with the Green-Gauss method.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"795-819"},"PeriodicalIF":1.7,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786825","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":"Extension of High-Order Lattice Boltzmann Flux Solver for Simulation of Three-Dimensional Compressible Flows","authors":"Jian Qin,&nbsp;Jie Wu,&nbsp;Qiushuo Qin","doi":"10.1002/fld.5377","DOIUrl":"https://doi.org/10.1002/fld.5377","url":null,"abstract":"<div>\u0000 \u0000 <p>In this paper, a high-order lattice Boltzmann flux solver (LBFS) based on flux reconstruction (FR) is presented for simulating the three-dimensional compressible flows. Unlike the original LBFS employing finite volume methods, the current method (FR-LBFS) can achieve arbitrary high-order accuracy with a compact stencil. High-order schemes based on finite volume methods often compromise parallel efficiency and complicate boundary treatment. In contrast, LBFS incorporates physical effects in calculating inviscid fluxes, providing superior shock-capturing capabilities over traditional approximate Riemann solvers. The present method combines the strengths of both FR and LBFS, yielding enhanced performance. Specifically, there is limited analysis of compact high-order LBFS in simulations of three-dimensional compressible flows. Several benchmark test cases are employed to validate the superiority of the current method, and the results show good agreement with established literature values. The shock tube problem and inviscid Taylor-Green vortex demonstrate the shock-capturing capability and low-dissipation characteristics of FR-LBFS. Meanwhile, the decaying homogeneous isotropic turbulent flow and the flow around a triangular airfoil highlight the accuracy of the current method in turbulence simulation. The obtained numerical results demonstrate that the proposed method holds considerable promise for applications in simulations of compressible and turbulent flows.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"820-829"},"PeriodicalIF":1.7,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786826","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":"Deep Learning Method for Airfoil Flow Field Simulation Based on Unet++","authors":"Xie Ruiling,&nbsp;Xu Jie,&nbsp;Chen Jianping,&nbsp;Tan Peizhi","doi":"10.1002/fld.5375","DOIUrl":"https://doi.org/10.1002/fld.5375","url":null,"abstract":"<div>\u0000 \u0000 <p>This paper investigates the accuracy of U-Net++ networks in predicting Reynolds-Averaged Navier-Stokes (RANS) solutions. The study employs the symbolic distance function (SDF) to represent geometry and flow conditions, utilizing parameterized airfoil data from the UIUC (University of Illinois at Urbana-Champaign) airfoil datasets. The research assesses the performance of multiple trained neural networks in predicting pressure and velocity distributions. Specifically, the study examines the influence of varying network weights on solution accuracy. Through the optimization of the model, the research demonstrates that the mean relative error is below 1.72% for a range of previously unseen wing shapes, with a computational speedup factor of up to 1,000× in certain scenarios. The accuracy achieved by this model underscores the significant potential of deep learning-based approaches as reliable tools for aerodynamic design and optimization.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"783-794"},"PeriodicalIF":1.7,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786799","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 Filtered Embedded Weighted Compact Non-Linear Scheme for Hyperbolic Conservation Law","authors":"Xuan Liu,&nbsp;Yaobing Min,&nbsp;Jinsheng Cai,&nbsp;Yankai Ma,&nbsp;Zhen-Guo Yan","doi":"10.1002/fld.5366","DOIUrl":"https://doi.org/10.1002/fld.5366","url":null,"abstract":"<div>\u0000 \u0000 <p>In situations where a wide range of flow scales are involved, the non-linear scheme should be capable of both shock capturing and low-dissipation. Most of the existing Weighted Compact Non-linear Schemes (WCNS) are too dissipative and incapable of achieving fourth-order for the two smooth stencils located on the same side of a discontinuity due to the weight deviations and the defect of the weighting strategy. In this paper, a novel filtered embedded WCNS is introduced for complex flow simulations involving both shock and small-scale structures. To overcome the above deficiency of existing WCNS, a pre-discrete mapping function is proposed to filter the weight deviation out and amend the inappropriate weights to ideal weights in smooth regions. Meanwhile, the embedded process is also implemented by this function, which is utilized to improve the resolution of shock capturing in certain discontinuity distributions. The pre-discrete mapping function is also extended to the WENO framework. The approximate-dispersion-relation analysis indicates that the scheme with the mapping function has lower dispersion and dissipation error than the WCNS-JS, WCNS-Z, and WCNS-T schemes. Numerical results show that WCNS with the new non-linear weights captures discontinuities sharply without obvious oscillation, has a higher resolution than other non-linear schemes, and has an obvious advantage in capturing small-scale structures.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"736-764"},"PeriodicalIF":1.7,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787193","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 Finite Element Method to Compute the Damping Rate and Frequency of Oscillating Fluids Inside Microfluidic Nozzles","authors":"Søren Taverniers,&nbsp;Svyatoslav Korneev,&nbsp;Christoforos Somarakis,&nbsp;Morad Behandish,&nbsp;Adrian J. Lew","doi":"10.1002/fld.5373","DOIUrl":"https://doi.org/10.1002/fld.5373","url":null,"abstract":"<div>\u0000 \u0000 <p>The computation of damping rates of an oscillating fluid with a free surface in which viscosity is small and surface tension high is numerically challenging. A typical application requiring such computation is drop-on-demand (DoD) microfluidic devices that eject liquid metal droplets, where accurate knowledge of the damping rates for the least-damped oscillation modes following droplet ejection is paramount for assessing jetting stability at higher jetting frequencies, as ejection from a nonquiescent meniscus can result in deviations from nominal droplet properties. Computational fluid dynamics (CFD) simulations often struggle to accurately predict meniscus damping unless very fine discretizations are adopted, so calculations are slow and computationally expensive. The faster alternative we adopt here is to compute the damping rate directly from the eigenvalues of the linearized problem. The presence of a surface tension term in Stokes or sloshing problems requires approximation of the meniscus displacements as well, which introduces additional complexity in their numerical solution. In this paper, we consider the combined effects of viscosity and surface tension, approximate the meniscus displacements, and construct a finite element method to compute the fluid's oscillation modes. We prove that if the finite element spaces satisfy a typical inf-sup condition, and the space of the meniscus displacements is a subset of the set of normal traces of the space of velocities, then the method is free of spurious modes with zero or positive damping rates. To construct numerical examples, we implement the method with Taylor-Hood elements for the velocity and pressure fields, and with continuous piecewise quadratic elements for the displacement of the meniscus. We verify the numerical convergence of the method by reproducing the solution to an analytical benchmark problem and two more complex examples with axisymmetric geometry. Remarkably, the spatial shape and temporal evolution (angular frequency and damping rate) of the set of least-damped oscillation modes are obtained in a matter of minutes, compared to days for a CFD simulation. The method's ability to quickly generate accurate estimates of fluid oscillation damping rates makes it suitable for integration into design loops for prototyping microfluidic nozzles.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"765-782"},"PeriodicalIF":1.7,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787195","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":"Direct Numerical Simulation and Implicit Large-Eddy Simulation of Shock Train in Channel Flow Using High Order Optimised Targeted Essentially Non-Oscillatory Schemes","authors":"Agneev Roy,&nbsp;Sandeep Kumar,&nbsp;Somnath Ghosh","doi":"10.1002/fld.5372","DOIUrl":"https://doi.org/10.1002/fld.5372","url":null,"abstract":"<div>\u0000 \u0000 <p>Direct numerical simulation (DNS) and implicit large-eddy simulation (LES) of turbulent channel flows with isothermal walls, with and without shock trains, are performed using a recently proposed high-order optimized targeted essentially non-oscillatory (TENO) scheme. Mean flow and turbulence statistics are presented and compared with those previously obtained from DNS using a bandwidth-optimized weighted essentially non-oscillatory (WENO) scheme with limiter. It is observed that the TENO scheme performs better than the WENO scheme in predicting the mean flow and Reynolds stresses in these flows. The optimized TENO scheme used here is found to be very suitable for performing implicit LES on a relatively coarse grid.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"713-735"},"PeriodicalIF":1.7,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787015","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":"Wetting and Drying Treatments With Mesh Adaptation for Shallow Water Equations Using a Runge–Kutta Discontinuous Galerkin Method","authors":"Camille Poussel,&nbsp;Mehmet Ersoy,&nbsp;Frédéric Golay","doi":"10.1002/fld.5365","DOIUrl":"https://doi.org/10.1002/fld.5365","url":null,"abstract":"<div>\u0000 \u0000 <p>This work is devoted to the numerical simulation of Shallow Water Equations involving dry areas, a moving shoreline and in the context of mesh adaptation. The space and time discretization using the Runge–Kutta Discontinuous Galerkin approach is applied to nonlinear hyperbolic Shallow Water Equations. Problems with dry areas are challenging for such methods. To counter this issue, special treatment is applied around the shoreline. This work compares three treatments, one based on Slope Modification, one based on p-adaptation and the last one based on eXtended Finite Element methods and mesh adaptation.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"692-712"},"PeriodicalIF":1.7,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786798","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 Practical Approach to Time-Varying Inflow Simulation and the Influence on Intermittent Airflow Within Urban Street Canyons","authors":"Yunwei Zhang,&nbsp;Lushuang Zhao,&nbsp;Lizhi Jing,&nbsp;Haiyan Miao,&nbsp;Junwei Su,&nbsp;Zhaolin Gu","doi":"10.1002/fld.5362","DOIUrl":"https://doi.org/10.1002/fld.5362","url":null,"abstract":"<div>\u0000 \u0000 <p>Based on large eddy simulations, intermittent airflow within an urban street canyon was simulated. The practice of time-varying inflow conditions (TVIC) required a time series of inflow wind velocity, which could be collected on a varying curve of the moving averaged measured data. The influences of the time interval of the wind series and the varying trend (or molded line) between adjacent data on airflow within the street canyon were analyzed. The results showed that TVIC would result in larger average wind velocity and turbulence intensity than that simulated under steady inflow conditions (SIC). The simulated total vertical air exchanges under TVIC would be one order of magnitude higher than that simulated under SIC. Airflow characteristics within street canyons were influenced by the varying trends and the time intervals of the time-series inflow wind. Average vertical wind velocity and turbulent kinetic energy (TKE) simulated under the stepped varying trend was higher than that under the jagged varying trend. The shorter the time interval, the larger the TKE within the street canyon. Vertical air exchanges induced by turbulence (ACH′) at the roof level simulated under the stepped molded lines were twice that of the jagged molded line. Under the time interval of 30 s, the ACH′ was significantly increased, which was 2.558 times that simulated with a time interval of 1 min. Thus, the suggested practical approach for time-varying inflow simulations is to obtain time-series wind data with a time interval of 1 min or less, and the linearly molded line would be critical; for larger time intervals, reasonable molded lines would be required.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 5","pages":"676-691"},"PeriodicalIF":1.7,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786797","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":"High-Order Alternative Formulation of Weighted Essentially Non-Oscillatory Scheme With Minimized Dispersion and Controllable Dissipation for Compressible Flows","authors":"Wei-Gang Zeng,&nbsp;Lu Liu,&nbsp;Li-Jin Zeng,&nbsp;Jian-Hua Pan,&nbsp;Jun-Ping Yin,&nbsp;Yu-Xin Ren","doi":"10.1002/fld.5364","DOIUrl":"https://doi.org/10.1002/fld.5364","url":null,"abstract":"<div>\u0000 \u0000 <p>Following the proposition of the original AWENO (Alternative Formulation of Weighted Essentially Non-Oscillatory) FD (Finite Difference) scheme, we construct the new AMDCD FD scheme, an Alternative formulation of the linear FD scheme with Minimized Dispersion and Controllable Dissipation, in this article. Spectral analysis shows that the proposed AMDCD FD scheme can be more efficient in resolving smooth solutions due to the flexibility in controlling dissipation. To efficiently solve compressible flows with discontinuities, we further combined the proposed AMDCD FD scheme with the original AWENO FD scheme using a hybrid interpolation scheme, in which the optimized linear MDCD (Minimized Dispersion and Controllable Dissipation) interpolation scheme would be switched to the nonlinear WENO (Weighted Essentially Non-Oscillatory) type interpolation scheme gradually as the flow structures are in transition from smooth region towards the vicinity of discontinuities. Therefore, the resulting hybrid AWENO-AMDCD FD scheme is suitable for solving compressible flows with broad-scale flow structures and/or shock waves. A series of one-, two-, and three-dimensional compressible flow problems are numerically tested to demonstrate the accuracy, superior resolution, as well as the robustness of the proposed hybrid AWENO-AMDCD FD scheme.</p>\u0000 </div>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"97 4","pages":"646-664"},"PeriodicalIF":1.7,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533437","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}