International Journal for Numerical Methods in Fluids最新文献

{"title":"An efficient high-order two-level explicit/implicit numerical scheme for two-dimensional time fractional mobile/immobile advection-dispersion model","authors":"Eric Ngondiep","doi":"10.1002/fld.5296","DOIUrl":"10.1002/fld.5296","url":null,"abstract":"<p>This article constructs a new two-level explicit/implicit numerical scheme in an approximate solution for the two-dimensional time fractional mobile/immobile advection-dispersion problem. The stability and error estimates of the proposed technique are deeply analyzed in the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mi>∞</mi>\u0000 </mrow>\u0000 </msup>\u0000 <mo>(</mo>\u0000 <mn>0</mn>\u0000 <mo>,</mo>\u0000 <mi>T</mi>\u0000 <mo>;</mo>\u0000 <msup>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$$ {L}^{infty}left(0,T;{L}^2right) $$</annotation>\u0000 </semantics></math>-norm. The developed approach is less time consuming, fourth-order in space and temporal accurate of order <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mo>(</mo>\u0000 <msup>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 <mo>−</mo>\u0000 <mfrac>\u0000 <mrow>\u0000 <mi>λ</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </mfrac>\u0000 </mrow>\u0000 </msup>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$$ Oleft({k}^{2-frac{lambda }{2}}right) $$</annotation>\u0000 </semantics></math>, where <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation>$$ k $$</annotation>\u0000 </semantics></math> is the time step and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>λ</mi>\u0000 </mrow>\u0000 <annotation>$$ lambda $$</annotation>\u0000 </semantics></math> denotes a positive parameter less than 1. This result shows that the two-level explicit/implicit formulation is faster and more efficient than a large class of numerical schemes widely discussed in the literature for the considered problem. Numerical experiments are performed to verify the theoretical studies and to demonstrate the efficiency of the new numerical method.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1305-1336"},"PeriodicalIF":1.7,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140940156","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 hybrid CPU-GPU paradigm to accelerate reactive CFD simulations","authors":"Federico Ghioldi,&nbsp;Federico Piscaglia","doi":"10.1002/fld.5297","DOIUrl":"10.1002/fld.5297","url":null,"abstract":"<p>The solution of reactive computational fluid dynamics (CFD) simulations is accelerated by the implementation of a hybrid central processing unit/graphics processing units (CPU/GPU) Finite Volume solver based on the operator-splitting strategy, where the chemistry integration is treated independently of the flow solution. The integration of ordinary differential equations (ODEs) describing the finite-rate chemical kinetics is solved by an adaptive multi-block explicit solver on GPUs, while the load of the fluid solution is distributed on a multicore CPU algorithm. The resulting speed-up for reactive CFD simulations is up to 10<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>×</mo>\u0000 </mrow>\u0000 <annotation>$$ times $$</annotation>\u0000 </semantics></math>; the performance gain increases with the size of the mechanism. The proposed implementation is general and can be applied to any CFD problem where the governing equations for the fluid transport are coupled with an ODE system. Code validation is performed against reference solutions on a selection of test cases involving reacting flows.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1461-1488"},"PeriodicalIF":1.7,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836184","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":"Hull form optimization research based on multi-precision back-propagation neural network approximation model","authors":"Jie Liu,&nbsp;Baoji Zhang,&nbsp;Yuyang Lai,&nbsp;Liqiao Fang","doi":"10.1002/fld.5291","DOIUrl":"10.1002/fld.5291","url":null,"abstract":"<p>In order to shorten the optimization cycle of ship design optimization and solve the time-consuming problem of computational fluid dynamics (CFD) numerical calculation, this paper proposes a multi-precision back-propagation neural network (MP-BP) approximation technology. Fewer high-precision ship samples and more low-precision ship samples were used to construct an approximate model, back-propagation (BP) neural network was used to train multi-precision samples. So that the approximate model is as close as possible to the real model, and achieving the effect of high-precision approximation model. Subsequently, numerical verification and typical hull form verification are given. Based on CFD and Rankine theory, the multi-objective design optimization framework for ship comprehensive navigation performance is constructed. The multi-objective approximation model of KCS ship is constructed by MP-BP approximation technology, and optimized by particle swarm optimization (PSO) algorithm. The results show that the multi-objective optimization design framework using the MP-BP approximation model can capture the global optimal solution and improve the efficiency of the entire hull form design optimization. It can provide a certain degree of technical support for green ship and low-carbon shipping.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1445-1460"},"PeriodicalIF":1.7,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836116","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":"Adaptive mesh based efficient approximations for Darcy scale precipitation–dissolution models in porous media","authors":"Shridhar Kumar,&nbsp;Pratibhamoy Das,&nbsp;Kundan Kumar","doi":"10.1002/fld.5294","DOIUrl":"10.1002/fld.5294","url":null,"abstract":"<p>In this work, we consider the Darcy scale precipitation–dissolution reactive transport 1D and 2D models in a porous medium and provide the adaptive mesh based numerical approximations for solving them efficiently. These models consist of a convection-diffusion-reaction PDE with reactions being described by an ODE having a nonlinear, discontinuous, possibly multi-valued right hand side describing precipitate concentration. The bulk concentration in the aqueous phase develops fronts and the precipitate concentration is described by a free and time-dependent moving boundary. The time adaptive moving mesh strategy, based on equidistribution principle in space and governed by a moving mesh PDE, is utilized and modified in the context of present problem for finite difference set up in 1D and finite element set up in 2D. Moreover, we use a predictor corrector based algorithm to solve the nonlinear precipitation–dissolution models. For equidistribution approach, we choose an adaptive monitor function and smooth it based on a diffusive mechanism. Numerical tests are performed to demonstrate the accuracy and efficiency of the proposed method by examples through finite difference approach for 1D and finite element approach in 2D. The moving mesh refinement accurately resolves the front location of Darcy scale precipitation–dissolution reactive transport model and reduces the computational cost in comparison to numerical simulations using a fixed mesh.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1415-1444"},"PeriodicalIF":1.7,"publicationDate":"2024-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836393","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":"An extended discontinuous Galerkin shock tracking method","authors":"Jakob Vandergrift,&nbsp;Florian Kummer","doi":"10.1002/fld.5293","DOIUrl":"10.1002/fld.5293","url":null,"abstract":"<p>In this paper, we introduce a novel high-order shock tracking method and provide a proof of concept. Our method leverages concepts from implicit shock tracking and extended discontinuous Galerkin methods, primarily designed for solving partial differential equations featuring discontinuities. To address this challenge, we solve a constrained optimization problem aiming at accurately fitting the zero iso-contour of a level set function to the discontinuities. Additionally, we discuss various robustness measures inspired by both numerical experiments and existing literature. Finally, we showcase the capabilities of our method through a series of two-dimensional problems, progressively increasing in complexity.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1384-1414"},"PeriodicalIF":1.7,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.5293","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140614726","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":"A modified forcing approach in the Rothman–Keller method for simulations of flow phenomena at low capillary numbers","authors":"Anand Sudha,&nbsp;Martin Rohde","doi":"10.1002/fld.5292","DOIUrl":"10.1002/fld.5292","url":null,"abstract":"<p>The lattice-Boltzmann method (LBM) is becoming increasingly popular for simulating multi-phase flows on the microscale because of its advantages in terms of computational efficiency. Many applications of the method are restricted to relatively simple geometries. When a more complex geometry is considered—circular and inclined microchannels—some important physical phenomena may not be accurately captured, especially at low capillary numbers. A Y-Y micro-fluidic channel, widely used for a range of applications, is an example of a more complex geometry. This work aims to capture the various flow phenomena, with an emphasis on parallel flow and leakage, using the Rothman–Keller (RK) model of the LBM. To this purpose, we modify the forcing term to implement the surface tension for use at low capillary numbers. We compare the simulation results of the RK model with and without the force modification with experiments, Volume of Fluid and the phase field method and observe that the modified forcing term is an improvement over the current RK model at low capillary numbers, and it also captures parallel flow and leakage more accurately than the other simulation techniques.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1365-1383"},"PeriodicalIF":1.7,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/fld.5292","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140589010","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":"A reduced smoothed integration scheme of the cell-based smoothed finite element method for solving fluid–structure interaction on severely distorted meshes","authors":"Tao He,&nbsp;Fang-Xing Lu,&nbsp;Xi Ma","doi":"10.1002/fld.5289","DOIUrl":"10.1002/fld.5289","url":null,"abstract":"<p>This article describes an inexpensive partitioned coupling strategy for computational fluid–structure interaction (FSI) admitting negative-Jacobian elements. The emphasis is very much on a reduced smoothed integration (RSI) scheme of the cell-based smoothed finite element method (CSFEM) using four-node quadrilateral (Q4) elements for a cost-effective solution to the Navier–Stokes (NS) equations. In the discrete fluid field, each Q4 element is considered as one single smoothing cell so as to diminish the smoothed integration loops substantially. However, the RSI scheme does not respect the stability condition of smoothed Galerkin weak-form integral in the CSFEM. To tackle this issue, a simple hourglass control is introduced to the under-integrated formulation of the NS solver. Importantly, the stabilized RSI scheme has an inbuilt advantage of its enormous tolerance towards negative-Jacobian elements. The developed technique is easy-to-implement and has been tested in various FSI examples adopting both fine and distorted meshes.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 8","pages":"1337-1364"},"PeriodicalIF":1.7,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140589005","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":"Therapeutic Potential of Morin Hydrate Against Rifampicin Induced Hepato and Renotoxicity in Albino Wistar Rats: Modulation of Organ Function, Oxidative Stress and Inflammatory Response.","authors":"Harvesh Kumar Rana, Amit Kumar Singh, Abhay Kumar Pandey","doi":"10.1007/s12291-023-01145-0","DOIUrl":"10.1007/s12291-023-01145-0","url":null,"abstract":"<p><p>Tuberculosis (TB) is a challenging public health issue, particularly in poor and developing countries. Rifampicin (RIF) is one of the most common first-line anti-TB drugs but it is known for its adverse effects on the hepato-renal system. The present study investigated the efficacy of morin hydrate (MH) in protecting hepato-renal damage inflicted by RIF in rats. RIF (50 mg/kg), and a combination of RIF (50 mg/kg) and MH (50 mg/kg) were administered orally for 4 weeks in rats. Silymarin (50 mg/kg) was used as a positive control. Increased levels of serological parameters such as AST, ALT, ALP, LDH, GGT, bilirubin, triglyceride, total cholesterol, urea, uric acid, creatinine, TNF-α, IFN-γ, IL-6 along with the decreased level of IL-10, total protein and albumin were used as markers of hepatic and renal injury. Oxidative damage in the tissues was measured by the increase in lipid peroxidation and decline in GSH, SOD and catalase activities. Histopathology of liver slices was used to study hepatic architecture. Four-week RIF treatment produced altered serological parameters with an increase in pro-inflammatory cytokines in serum suggesting hepatotoxicity and nephrotoxicity. The antioxidant status of the liver and kidney (increased lipid peroxidation and decline in GSH, SOD and catalase) was compromised. Cellular damage and necrosis were observed in liver slices. MH supplementation with RIF improved hepato-renal functions by restoring the serum and tissue markers towards normal values. Histological observations authenticated the results. MH supplementation also reduced the production of pro-inflammatory cytokines. Thus, the results revealed that MH provides protection against RIF-induced hepato-renal injury.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"95 1","pages":"197-206"},"PeriodicalIF":1.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10987459/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76652043","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":"Comparative analysis of nondimensionalization approaches for solving the 2-D differentially heated cavity problem","authors":"F. I. Molina-Herrera,&nbsp;L. I. Quemada-Villagómez,&nbsp;J. L. Navarrete-Bolaños,&nbsp;H. Jiménez-Islas","doi":"10.1002/fld.5285","DOIUrl":"10.1002/fld.5285","url":null,"abstract":"<p>This work reports a numerical study on the effect of three nondimensionalization approaches that are commonly used to solve the classic problem of the 2-D differentially heated cavity. The governing equations were discretized using orthogonal collocation with Legendre polynomials, and the resulting algebraic system was solved via Newton–Raphson method with LU factorization. The simulations were performed for Rayleigh numbers between 10³ and 10⁸, considering the Prandtl number equal to 0.71 and a geometric aspect ratio equal to 1, analyzing the convergence and the computation time on the flow lines, isotherms and the Nusselt number. The mesh size that provides independent results was 51 × 51. Approach II was the most suitable for the nondimensionalization of the differentially heated cavity problem.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 7","pages":"1276-1303"},"PeriodicalIF":1.8,"publicationDate":"2024-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140362246","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 mathematical-boundary-recognition domain-decomposition Lattice Boltzmann method combined with large eddy simulation applied to airfoil aeroacoustics simulation","authors":"Qi Jia,&nbsp;Jin Zhang,&nbsp;Wen-zhi Liang,&nbsp;Pei-qing Liu,&nbsp;Qiu-lin Qu","doi":"10.1002/fld.5287","DOIUrl":"10.1002/fld.5287","url":null,"abstract":"<p>Being a direct computational aeroacoustics method, Lattice Boltzmann method (LBM) has great potential and broad application perspective in the field of numerical simulation of aerodynamic noise due to its low dispersion and low dissipation. A series of numerical algorithms and the related improvements based on the standard LBM method are proposed and developed in this paper to adapt to the airfoil noise calculation with complex grid at middle-high Reynolds number. First, a new mathematical-boundary-recognition algorithm based on Green's formula is proposed to deal with complex curved geometric models, which is validated by three-element airfoil 30P30N benchmark. Then, in order to reduce grid redundancy and improve computing efficiency, the grid refinement technique of domain decomposition model (DDM) is adopted and also improved, which is verified by calculating the flow and sound fields around 2D and 3D cylinders at Reynolds number equal to 90,000. Finally, three different LES turbulence models are combined with the standard MRT-LBM method, where different finite difference schemes are used to solve Reynolds stress tensor which is different from the traditional one. Through the direct acoustic numerical simulation of NACA0012 airfoil at Reynolds number equal to 200,000, the effects of Smagorinsky models and Wall-adapting local eddy-viscosity (WALE) model on aerodynamic noise prediction are compared and analyzed. Overall, the proposed methodology is shown to be appropriate for predicting the aerodynamic noise at low Mach number and can successfully simulate the generation and propagation of far field acoustics.</p>","PeriodicalId":50348,"journal":{"name":"International Journal for Numerical Methods in Fluids","volume":"96 7","pages":"1250-1275"},"PeriodicalIF":1.8,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140370669","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}