Computers & Fluids最新文献

{"title":"Blade-resolved and actuator line simulations of rotor wakes","authors":"André F.P. Ribeiro ,&nbsp;Thomas Leweke ,&nbsp;Aliza Abraham ,&nbsp;Jens N. Sørensen ,&nbsp;Robert F. Mikkelsen","doi":"10.1016/j.compfluid.2024.106477","DOIUrl":"10.1016/j.compfluid.2024.106477","url":null,"abstract":"<div><div>This work concerns high-fidelity numerical simulations of a rotor wake, with focus on the tip vortices and their stability. Blade-resolved and actuator line lattice-Boltzmann simulations are performed on a symmetric baseline rotor, as well as on a rotor with asymmetries. The asymmetry has the purpose of destabilizing the tip vortices to enhance wake recovery and hence the performance of potential downstream turbines. Limitations in the actuator line method are highlighted, and we show the potential of addressing these limitations with a so-called “preset” actuator line, where the forces are extracted from blade-resolved simulations, or an analytical load model, which as input only requires the thrust and power coefficients. Simulations agree well with experimental results and leapfrogging is captured, even with a coarse actuator line simulation. The asymmetric rotor is shown to improve power in the far-wake by 12%.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"287 ","pages":"Article 106477"},"PeriodicalIF":2.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744110","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":"Computers and fluids special issue “Mesoscopic methods and their applications to CFD”","authors":"Yanguang Yang,&nbsp;Ming Fang,&nbsp;Weidong Li,&nbsp;Zhaoli Guo,&nbsp;Manfred Krafczyk,&nbsp;Li-Shi Luo","doi":"10.1016/j.compfluid.2024.106489","DOIUrl":"10.1016/j.compfluid.2024.106489","url":null,"abstract":"","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"286 ","pages":"Article 106489"},"PeriodicalIF":2.5,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756722","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":"SPH simulations of non-isothermal viscoplastic free-surface flows incorporating Herschel-Bulkley-Papanastasiou model","authors":"Xiaoyang Xu,&nbsp;Wei Yu","doi":"10.1016/j.compfluid.2024.106491","DOIUrl":"10.1016/j.compfluid.2024.106491","url":null,"abstract":"<div><div>In this paper, an improved smoothed particle hydrodynamics (SPH) method is employed to accurately simulate non-isothermal viscoplastic free surface flows, wherein the viscoplastic behavior of the fluid is precisely captured through the incorporation of the Herschel-Bulkley-Papanastasiou constitutive model. To suppress the non-physical oscillation arising from the weakly compressible hypothesis within the pressure field, the density dissipation term is incorporated into the mass conservation equation. To address the tensile instability arising from the uneven distribution of particles, the particle shifting technique is incorporated as a solution. To enhance the precision and ensure numerical stability of the gradient operator, a kernel gradient correction algorithm is implemented. The improved SPH method is employed for numerically simulating the non-isothermal viscoplastic mixed convection, dam-break flow and droplet impacting the solid wall. The effectiveness of the improved SPH method in tackling the complexities of non-isothermal viscoplastic fluid is validated through a rigorous comparison of its outcomes with those derived from alternative numerical methodologies. The assessment of the numerical convergence of the improved SPH method is undertaken through the utilization of varying initial particle spacings. The numerical outcomes demonstrate that the improved SPH method adeptly and precisely delineates the heat transfer mechanisms, intricate rheological properties, as well as the dynamic variation characteristics of the free surface in non-isothermal viscoplastic free surface flows.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"287 ","pages":"Article 106491"},"PeriodicalIF":2.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702762","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":"High-order gas kinetic flux solver with TENO-THINC scheme for compressible flows","authors":"Lan Jiang ,&nbsp;Jie Wu ,&nbsp;Liming Yang ,&nbsp;Qiushuo Qin","doi":"10.1016/j.compfluid.2024.106492","DOIUrl":"10.1016/j.compfluid.2024.106492","url":null,"abstract":"<div><div>Although gas kinetic schemes (GKS) have been widely used as a potent tool for simulating compressible flows, they exhibit numerous drawbacks. Since most GKS are constructed based on the Maxwellian distribution function or its equivalent, the theoretical derivation and flux expression are often extremely complicated, which may result in lower calculation efficiency compared to traditional methods in computational fluid dynamics. In this paper, a circular function-based gas kinetic flux solver (C-GKFS) combined with a hybrid targeted essentially non-oscillatory-tangent of hyperbola for INterface capturing (TENO-THINC) scheme is presented for simulating two-dimensional compressible flows. The C-GKFS, which simplifies the Maxwellian distribution function into a circular function, significantly enhances computing efficiency. The TENO-THINC scheme, which combines the standard TENO scheme for smooth regions with the THINC scheme for non-smooth discontinuities, preserves low dissipation for smooth flow while effectively resolves the profile of jump for shock and contact waves. As a result, a simple high-order C-GKFS is obtained, which reduces complexity to facilitate practical engineering applications. Some benchmark problems are simulated, and good agreement can be obtained compared with reference data, which demonstrates that the TENO-THINC based C-GKFS achieves the desired accuracy and performs significantly better than the standard TENO scheme.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"287 ","pages":"Article 106492"},"PeriodicalIF":2.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703519","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 new sharing function for the common-weights WENO reconstruction of the Euler equations","authors":"Yiqiu Jin ,&nbsp;Yiqing Shen ,&nbsp;Guowei Yang ,&nbsp;Guannan Zheng","doi":"10.1016/j.compfluid.2024.106479","DOIUrl":"10.1016/j.compfluid.2024.106479","url":null,"abstract":"<div><div>Recently, one kind of common-weights weighted essentially non-oscillatory (Co-WENO) scheme was proposed to solve the Euler equations of the compressible flows. Different from the usual component-wise weighting methods, common-weights means that, on a global stencil, one set of weights is commonly shared by all components. Hence, the Co-WENO scheme can keep the same contribution on each component numerical flux and is more efficient than the component-wise weighting methods. This paper develops the Co-WENO reconstruction of the primitive variables applied in the Riemann solvers of Euler equations. A more robust sharing function (used to calculate the common weights) is proposed by taking into account the characteristic of the compressible wave (the effect of Mach number). Numerical results show that the Co-WENO scheme based on the new sharing function has good robustness and low numerical dissipation.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"287 ","pages":"Article 106479"},"PeriodicalIF":2.5,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Eulerian-Lagrangian decomposition for scalar transport at high schmidt number with adaptive particle creation and removal","authors":"A. Karimi Noughabi ,&nbsp;M. Leer ,&nbsp;I. Wlokas ,&nbsp;A. Kempf","doi":"10.1016/j.compfluid.2024.106490","DOIUrl":"10.1016/j.compfluid.2024.106490","url":null,"abstract":"<div><div>At high Schmidt or Prandtl numbers, scalar length scales are smaller than velocity scales, so they can only be resolved if a much finer grid is used and if numerical diffusion is managed carefully. This paper presents a numerical approach based on an Euler-Lagrangian decomposition method to prevent the numerical diffusion or dispersion of the scalar fields and to reduce the computational cost of flow simulations at high Schmidt numbers. This method decomposes the scalar field to the sum of i) a low-wavenumber component transported in the Eulerian framework using a conventional finite volume scheme with a numerical resolution according to the Kolmogorov scale and ii) a high-wavenumber component, described by Lagrangian particles to reconstruct the steep gradients in the scalar field. Depending on the local flow state, gradients can get steeper or flatter, requiring the transfer of information from the low- to the high-wavenumber fields and vice versa, which must be represented by particle creation or removal. New approaches are presented and tested for particle generation and removal on a 2D single vortex and a turbulent mixing layer across a Schmidt number range from 10 to 1000. We analyze scalar contours and conduct statistical assessments using probability density functions (PDF), mean squared error (MSE), and the structural similarity index measure (SSIM) for varying particle removal thresholds. The results confirm that, compared to the Eulerian description, the new approach can resolve smaller structures in the scalar field. Furthermore, particle removal not only reduces the number of particles without compromising accuracy, but it also, perhaps counter-intuitively, increases accuracy, where the low particle density would create excessive noise.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"287 ","pages":"Article 106490"},"PeriodicalIF":2.5,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Efficient quantum lattice gas automata","authors":"Antonio David Bastida Zamora ,&nbsp;Ljubomir Budinski ,&nbsp;Ossi Niemimäki ,&nbsp;Valtteri Lahtinen","doi":"10.1016/j.compfluid.2024.106476","DOIUrl":"10.1016/j.compfluid.2024.106476","url":null,"abstract":"<div><div>This study presents a novel quantum algorithm for lattice gas automata simulation with a single time step, demonstrating logarithmic complexity in terms of <span><math><mrow><mi>C</mi><mi>X</mi></mrow></math></span> gates. The algorithm is composed of three main steps: collision, mapping, and propagation. A computational complexity analysis and a comparison using different error rates and number of shots are provided. Despite the impact of noise, our findings indicate that accurate simulations could be achieved already on current noisy devices. This suggests potential for efficient simulation of classical fluid dynamics using quantum lattice gas automata, conditional on advancements to expand the current method to multiple time steps and state preparation.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"286 ","pages":"Article 106476"},"PeriodicalIF":2.5,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658459","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":"Energy-consistent discretization of viscous dissipation with application to natural convection flow","authors":"B. Sanderse ,&nbsp;F.X. Trias","doi":"10.1016/j.compfluid.2024.106473","DOIUrl":"10.1016/j.compfluid.2024.106473","url":null,"abstract":"<div><div>A new energy-consistent discretization of the viscous dissipation function in incompressible flows is proposed. It is <em>implied</em> by choosing a discretization of the diffusive terms and a discretization of the local kinetic energy equation and by requiring that continuous identities like the product rule are mimicked discretely. The proposed viscous dissipation function has a quadratic, strictly dissipative form, for both simplified (constant viscosity) stress tensors and general stress tensors. The proposed expression is not only useful in evaluating energy budgets in turbulent flows, but also in natural convection flows, where it appears in the internal energy equation and is responsible for viscous heating. The viscous dissipation function is such that a <em>consistent total energy balance</em> is obtained: the ‘implied’ presence as sink in the kinetic energy equation is exactly balanced by explicitly adding it as source term in the internal energy equation.</div><div>Numerical experiments of Rayleigh–Bénard convection (RBC) and Rayleigh–Taylor instabilities confirm that with the proposed dissipation function, the energy exchange between kinetic and internal energy is exactly preserved. The experiments show furthermore that viscous dissipation does not affect the critical Rayleigh number at which instabilities form, but it does significantly impact the development of instabilities once they occur. Consequently, the value of the Nusselt number on the cold plate becomes larger than on the hot plate, with the difference increasing with increasing Gebhart number. Finally, 3D simulations of turbulent RBC show that energy balances are exactly satisfied even for very coarse grids. Therefore, the proposed discretization also forms an excellent starting point for testing sub-grid scale models and is a useful tool to assess energy budgets in any turbulence simulation, with or without the presence of natural convection.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"286 ","pages":"Article 106473"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Gas-kinetic unified algorithm for aerodynamics covering various flow regimes by computable modeling of Boltzmann equation","authors":"Zhi-Hui Li ,&nbsp;Yong-Dong Liang ,&nbsp;Ao-Ping Peng ,&nbsp;Jun-Lin Wu ,&nbsp;Hao-Gong Wei","doi":"10.1016/j.compfluid.2024.106472","DOIUrl":"10.1016/j.compfluid.2024.106472","url":null,"abstract":"<div><div>The gas-kinetic unified algorithm (GKUA), to solve the modeling of the Boltzmann equation, has been developed to study the aerothermodynamics problems with the effects of wall activation energy covering various flow regimes. The unified velocity distribution function equation could be accordingly presented on the basis of the Boltzmann–Shakhov model. To remove the dependence of the distribution function on velocity space, the conservational discrete velocity ordinate method has been developed for hypervelocity flows. The gas-kinetic finite difference scheme is constructed to directly solve the discrete velocity distribution functions by the operator splitting technique. The discrete velocity numerical integration method with the Gauss-type weight function has been developed to evaluate the macroscopic flow variables. Specially, to model the real physical process between gas molecules and the surface, the Maxwell-type gas-surface interaction model has been presented by the MD (molecular dynamic) simulation to obtain the energy adaptability coefficient. The multi-processing domain decomposition strategy and parallel implementation of high parallel efficiency and expansibility designed for the gas-kinetic numerical method is presented with good load balance and data communication efficiency. To validate the accuracy and feasibility of the present algorithm, the supersonic flows past two-dimensional circular cylinder are simulated covering various flow regimes. The results are in good agreement with the related theoretical, DSMC (Direct Simulation Monte Carlo), N–S (Navier–Stokes), and experimental data. The hypersonic reentry flows with the effects of wall activation energy around the Tianzhou-5 cargo spacecraft are simulated by the present GKUA and the massive parallel strategy. It has been confirmed that the present algorithm from the gas-kinetic point of view probably provides a promising approach to resolve the hypersonic aerothermodynamic problems with the complete spectrum of flow regimes during the re-entry and disintegration of the large-scale spacecraft.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"287 ","pages":"Article 106472"},"PeriodicalIF":2.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703302","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":"The numerical analysis of complete and partial electrocoalescence in the droplet-layer system employing the sharp interface technique for multiphase-medium simulation","authors":"Grigorii Yagodin,&nbsp;Ilia Elagin,&nbsp;Sergei Vasilkov,&nbsp;Vladimir Chirkov","doi":"10.1016/j.compfluid.2024.106478","DOIUrl":"10.1016/j.compfluid.2024.106478","url":null,"abstract":"<div><div>In this paper, the coalescence of a drop of water suspended in oil with a layer of water under the influence of a constant electric field is numerically investigated. Unlike most existing studies, the calculations are based on the application of the arbitrary Lagrangian-Eulerian method (ALEM), also called the moving mesh method, which belongs to the class of methods for modeling two-phase liquids with a sharp interface. Using this approach made it possible to avoid a false \"escape\" of the surface charge from the interface, which often occurs when using methods involving a diffuse interface. Despite the fact that ALEM does not allow describing topology changes by default, a numerical model was implemented in which the calculation is divided into three parts: the convergence of the drop and the layer before the moment of touch; the manual construction of the bridge at the moment of touch; the union of the drop and the layer. The developed model allowed us to obtain three possible modes of this process: complete coalescence, partial coalescence and a mode of stretching which has not practically been considered yet. The dependence of the volume of the separated secondary droplet on the size of the initial droplet and the average intensity of the applied electric field is obtained. The model showed good quantitative agreement with experimental studies. It has been shown that generally, the spots where the bridge and the neck are formed in case of partial coalescence do not coincide. A map of coalescence modes was obtained, i.e., the dependence of the transition threshold from coalescence to partial coalescence and from partial coalescence to stretching regime in a wide range of radii of initial droplets and electric field strengths. It has been shown that there is a maximum field strength at which droplets of any size merge with the layer. This map makes it possible to predict the coalescence regime in electrocoalescer. The proposed modeling technique can be used to calculate electrocoalescence modes at various values of the main parameters, which will help to optimize electrocoalescers at the design stage.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"286 ","pages":"Article 106478"},"PeriodicalIF":2.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657996","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}