Computers & Fluids最新文献

{"title":"Analysis of the central-moments-based lattice Boltzmann method for the numerical modelling of the one-dimensional advection-diffusion equation: Equivalent finite difference and partial differential equations","authors":"Goncalo Silva","doi":"10.1016/j.compfluid.2024.106535","DOIUrl":"10.1016/j.compfluid.2024.106535","url":null,"abstract":"<div><div>This work presents a detailed theoretical analysis of the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM), formulated on central moment (CM) space, for the numerical modelling of the one-dimensional advection-diffusion equation (ADE) with a constant velocity and diffusion coefficient, based on the D1Q3 lattice. Other LBM collision operators, such as single-relaxation-time Bhatnagar–Gross–Krook (BGK), regularized (REG) and MRT in raw moment (RM) space are also considered in this study. Without recurring to asymptotic analyses, such as the Chapman–Enskog expansion, we investigate the approximation of the MRT-CM with respect to the ADE by deriving its equivalent finite difference (EFD) scheme, which obeys an explicit four-level finite difference scheme at discrete level. Its steady-state limit follows a standard central differencing scheme for the steady ADE, yet with possible artefacts in the effective diffusion coefficient. Then, through the Taylor expansion of the EFD scheme, a detailed accuracy analysis, based on the equivalent partial differential (EPD) equation, reveals the leading order truncation errors associated with each collision model under study. Although MRT-CM and MRT-RM models have similar error structures, the former has a much reduced and simpler form, particularly in the dispersion error term, which might explain the improved Galilean invariance of the CM model. Through a suitable combination of the MRT free parameters (either in RM or CM bases), it is possible to improve its accuracy from second- to fourth-order. After that, we study the necessary and sufficient stability conditions of the MRT-CM, and its relation with other collision operators, based on the von Neumann stability analysis of the derived EFD schemes. Unexpectedly, the MRT-CM appears to support a narrower stability domain than the MRT-RM model, particularly at higher advection velocities, which can be tracked down to the inclusion of additional terms in the stability condition of the former that scale with higher order polynomials of the advection velocity. Finally, some numerical tests for the ADE on 1D unbounded domains are conducted, which confirm this work theoretical conclusions on the MRT-CM performance.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106535"},"PeriodicalIF":2.5,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148236","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":"New higher-order super-compact scheme to study the uniform and non-uniform wall heating effect on 3D MHD natural convection and entropy generation","authors":"Ashwani Punia,&nbsp;Rajendra K. Ray","doi":"10.1016/j.compfluid.2024.106538","DOIUrl":"10.1016/j.compfluid.2024.106538","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This research introduces a new higher-order super-compact (HOSC) finite difference scheme to study magnetohydrodynamic (MHD) natural convection within a 3D cubic cavity filled with molten lithium. The HOSC scheme, implemented for the first time in this context, provides an advanced analysis of the thermal behavior under various wall heating conditions, including uniform and non-uniform heating. The study comprehensively explores the effects of different Hartmann numbers (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;25&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;150&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) and Rayleigh numbers (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), with a fixed Prandtl number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;065&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) for molten lithium. Three distinct heating scenarios on the left wall (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) of the cubic cavity are investigated: uniform heating (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), &lt;span&gt;&lt;math&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;-dependent non-uniform heating (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;sin&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;π&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), and combined &lt;span&gt;&lt;math&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;-dependent non-uniform heating (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;sin&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;π&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;sin&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;π&lt;/mi&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;). The results show that the HOSC scheme effectively captures the impact of varying &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; on the temperature distribution and flow field, revealing that increased &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; enhances heat transfer due to stronger convection, while higher &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; reduces heat transfer by slowing fluid motion. Notably, as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; increases from &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; at a fixed &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;25&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, the maximum Nusselt number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;u&lt;/mi&gt;&lt;","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106538"},"PeriodicalIF":2.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148238","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":"Characterization of atmospheric and wind farm turbulence","authors":"Jagdeep Singh,&nbsp;Jahrul M Alam","doi":"10.1016/j.compfluid.2024.106537","DOIUrl":"10.1016/j.compfluid.2024.106537","url":null,"abstract":"<div><div>Developing and assessing subgrid-scale models for characterizing atmospheric and wind farm turbulence is one of the key research areas within the wind energy community. This article presents the interaction of atmospheric and wind farm turbulence using scale-adaptive large-eddy simulation. Atmospheric turbulence has been incorporated by employing the stochastic forcing method to linearized Navier–Stokes equations, which interacted with a staggered cluster of utility-scale 41 wind turbines. The effect of atmospheric turbulence on wind turbine wakes was characterized by comparing scale-adaptive large-eddy simulation results with three reference data obtained from three other subgrid-scale models: Smagorinsky model, Deardorff’s one-equation turbulence kinetic energy model, and dynamic Deardorff model. The results suggest that vortex-stretching and strain skewness can accelerate wake recovery because scale-adaptive large-eddy simulation captured more than 90% of the turbulence kinetic energy, outperforming the other three models. The atmospheric turbulence in a wind farm has been characterized by considering mean vertical profiles, wake recovery, turbulence statistics, wavelet energy spectra, and power production. Finally, the interaction between atmospheric turbulence and wind turbines was evaluated through joint probability distribution of the second and the third invariant of velocity gradient and strain rate tensors and that of vortex-stretching and strain skewness. The results highlight the importance of considering vortex-stretching and strain skewness in turbine design, siting decisions, and wind farm layout optimization.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106537"},"PeriodicalIF":2.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148240","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":"A numerical investigation into the interaction between rain and water waves","authors":"Claire Bergin ,&nbsp;Wouter Mostert ,&nbsp;Vikram Pakrashi ,&nbsp;Frederic Dias","doi":"10.1016/j.compfluid.2024.106534","DOIUrl":"10.1016/j.compfluid.2024.106534","url":null,"abstract":"<div><div>Rainfall has been observed to damp water waves. However, the long observed effects of rainfall on water waves have not been much investigated numerically. In this paper, numerical simulations are conducted to explore the effect of rainfall on two-dimensional water waves. The Basilisk software, used herein, solves the two-phase, incompressible, Navier–Stokes equations on adaptive Cartesian meshes. In the present simulations, a monochromatic wave is generated within the domain boundary and periodically moves from left to right through the domain. Rainfall with representative drop diameter distributions, as well as accurate terminal velocities, is generated to fall on the monochromatic wave. The energy of the receiving body of water is tracked for evidence of dissipation of the wave induced by the rainfall. The simulation is run for different values of the wave steepness, ranging from non-breaking waves to plunging breakers. It is found that, in no wind conditions, the presence of rainfall can reduce wave energy, particularly in the non-breaking case. In the future, a more realistic configuration with three-dimensional waves and wind will be considered.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106534"},"PeriodicalIF":2.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147868","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 freestream preserving algorithm for the flux reconstruction method implemented on tetrahedral element","authors":"Weiheng Pan ,&nbsp;Zhicong Kang ,&nbsp;Liang Xie","doi":"10.1016/j.compfluid.2024.106532","DOIUrl":"10.1016/j.compfluid.2024.106532","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In computational fluid dynamics, curvilinear elements are frequently used to fit boundaries. Metric terms are involved by the map from these curvilinear elements to the standard reference element. If these metric terms are calculated inappropriately, the solutions may be incorrect or even divergent. It is well known that the freestream solution could be used to examine whether the metrics are discretized correctly or not. Namely, the metric terms must be computed in such a way that the freestream could be preserved, which is known as the freestream preservation problem. Although this problem has been studied extensively in the finite difference approach, there are still unanswered questions in the high-order schemes for the unstructured mesh, such as the discontinuous Galerkin (DG) method and the flux reconstruction (FR) algorithm. The existing research about the freestream preservation property for these high-order schemes mainly focused on the unstructured hexahedral element. Although some algorithms had been extended to the unstructured tetrahedral element (Chana and Wilcox, 2019), it remains unclear whether the conditions to preserve freestream on the tetrahedral element agree with those of the hexahedral element. In this paper, we extend the work of Abe and his colleagues (Abe et al., 2015) on the freestream preservation problem in the FR method from the unstructured hexahedral element to the tetrahedral cell. The algorithms of both the non-conservative and symmetrical-conservative metrics occurred in their research have been extended to the tetrahedral element in our research. We also analyzed the conditions under which these algorithms could achieve freestream preservation property and found that they are not equal to those of the unstructured hexahedral cell. If &lt;span&gt;&lt;math&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; are used to respectively represent the order of solution and grid, the algorithm constructed in the non-conservative form could preserve freestream when &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for the hexahedral element, as depicted by Abe et al. (2015). However, this condition becomes &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; on the tetrahedral element according to our research. In the symmetrical-conservative metrics, this condition changes from &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; on the hexahedral element (Abe et al., 2015) to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; on the tetrahedral cell. Namely, compared to the hexahedral element, these conditions are relaxed for the tetrahedral element. To verify our findings, two three-dimensional cases are performed. The results of these numerical simulations have confirmed that the algorithms constructed in our research are successful and t","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106532"},"PeriodicalIF":2.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148237","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":"Assessment of thermochemical models on nonequilibrium flowfield and radiation in shock-heated nitrogen","authors":"Yuzhe Zhang ,&nbsp;Qizhen Hong ,&nbsp;Xiaoyong Wang ,&nbsp;Chao Yang ,&nbsp;Quanhua Sun","doi":"10.1016/j.compfluid.2024.106533","DOIUrl":"10.1016/j.compfluid.2024.106533","url":null,"abstract":"<div><div>Numerical simulations based on various physical models are performed to study thermochemical nonequilibrium flowfield and radiation in high enthalpy shock-heated nitrogen flows and compared against available experimental shock tube data. The physical models include both the two-temperature (2T) model and the four-temperature (4T) model, each integrated with different vibration-dissociation (VD) coupling models. For Sharma and Gillespie’s shock tube experiment, it is observed that the 4T model demonstrates satisfactory agreement with experimental rotational and vibrational temperatures, while the 2T results fall short of achieving comparable accuracy. When employing identical equilibrium dissociation rate coefficients and energy relaxation times, the modified Marrone–Treanor (MMT) model shows the lowest dissociation rate and the highest peak rotational temperature, which is closer to experimental data, in comparison to the Park and Marrone–Treanor (MT) models. For recent experiments conducted at the Electric-Arc Shock Tube facility (Shot 37 and Shot 40), our 4T-QSS results with the MMT model give the predictions for nonequilibrium radiative metrics closest to experimental data among the three VD models considered, although discrepancies compared to the experiments are still observed. Moreover, our investigation concludes that the influences of radiative cooling, rate coefficients of associative ionization and heavy-particle impact dissociation of N₂, and predissociation of the N₂(C) state on nonequilibrium radiative metrics are insignificant for these two shots. The discrepancies (persisted when incorporating various modeling options) in both nonequilibrium radiative metric and radiance versus position between the present calculations and experimental measurement indicate the necessity of employing a detailed state-to-state model and considering the shock tube-related phenomena to reproduce the experimental data.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106533"},"PeriodicalIF":2.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148234","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":"Hybrid parallel discrete adjoints in SU2","authors":"Johannes Blühdorn ,&nbsp;Pedro Gomes ,&nbsp;Max Aehle ,&nbsp;Nicolas R. Gauger","doi":"10.1016/j.compfluid.2024.106528","DOIUrl":"10.1016/j.compfluid.2024.106528","url":null,"abstract":"<div><div>The open-source multiphysics suite SU2 features discrete adjoints by means of operator overloading automatic differentiation (AD). While both primal and discrete adjoint solvers support MPI parallelism, hybrid parallelism using both MPI and OpenMP has only been introduced for the primal solvers so far. In this work, we enable hybrid parallel discrete adjoint solvers. Coupling SU2 with OpDiLib, an add-on for operator overloading AD tools that extends AD to OpenMP parallelism, marks a key step in this endeavour. We identify the affected parts of SU2’s advanced AD workflow and discuss the required changes and their tradeoffs. Detailed performance studies compare MPI parallel and hybrid parallel discrete adjoints in terms of memory and runtime and unveil key performance characteristics. We showcase the effectiveness of performance optimizations and highlight perspectives for future improvements. At the same time, this study demonstrates the applicability of OpDiLib in a large code base and its scalability on large test cases, providing valuable insights for future applications both within and beyond SU2.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106528"},"PeriodicalIF":2.5,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148235","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":"A hybrid phase field-volume of fluid method for simulating dynamically evolving interfaces in multiphase flows","authors":"Atin Kumar Dolai ,&nbsp;Vinod Pandey ,&nbsp;Gautam Biswas ,&nbsp;Suman Chakraborty","doi":"10.1016/j.compfluid.2024.106536","DOIUrl":"10.1016/j.compfluid.2024.106536","url":null,"abstract":"<div><div>Moving boundary problems are ubiquitous in a plethora of applications encompassing nature and engineering, featuring interfaces that dynamically evolve with space and time. Despite the advancements in high performance computing over the recent years, the reported computational techniques for addressing such classes of problems continue to be challenged by a physically-consistent representation of the phase boundary topology. This deficit stems from the fact that whereas the established interface capturing techniques such as the volume of fluid (VOF) and the level set (LS) and a combination thereof (CLS-VOF) introduce mathematical variables for constructing the physical interface, the numerical parameters controlling the same may not necessarily connect with the fundamental thermodynamic considerations. On the other hand, the thermodynamically routed approaches such as phase field methods render to be computationally expensive while addressing an experimentally tractable physical problem where it may be difficult to map the experimental and simulation parameters. Bridging this gap, here we report a new hybrid interface capturing scheme that aims to amalgamate the computationally efficient interface construction approach for the VOF method and the thermodynamically-premised free energy-based diffuse interface description of the phase-field method. This enables the use of a standard second-order convection-diffusion scheme to apply a mass-conservative phase field formalism with standardized numerical parameters for interfacial advection and diffusion as opposed to the otherwise compulsive requirement of a fourth order differential equation for describing the phase field space for complying with the mass conservation constraint. We illustrate the efficacy of our method by benchmarking with reference to the established results on bubble dynamics, Rayleigh Taylor instability and film boiling. Our findings indicate the potential efficacy of this new approach as a balance between physical consistency and computational economy.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106536"},"PeriodicalIF":2.5,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148232","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":"Semi-implicit quasi-Lagrangian Voronoi approximation for compressible viscous fluid flows","authors":"Ondřej Kincl ,&nbsp;Ilya Peshkov ,&nbsp;Walter Boscheri","doi":"10.1016/j.compfluid.2024.106530","DOIUrl":"10.1016/j.compfluid.2024.106530","url":null,"abstract":"<div><div>This paper contributes to the recent investigations of Lagrangian methods based on Voronoi meshes. The aim is to design a new conservative numerical scheme that can simulate complex flows and multi-phase problems with more accuracy than SPH (Smoothed Particle Hydrodynamics) methods but, unlike diffuse interface models on fixed grid topology, does not suffer from the deteriorating quality of the computational grid. The numerical solution is stored at particles, which move with the fluid velocity and also play the role of the generators of the computational mesh, that is efficiently re-constructed at each time step. The main novelty stems from combining a quasi-Lagrangian Voronoi scheme with a semi-implicit integrator for compressible flows. This allows to model low-Mach number flows without the extremely stringent stability constraint on the time step and with the correct scaling of numerical viscosity. The implicit linear system for the unknown pressure is obtained by splitting the reversible from the irreversible (viscous) part of the dynamics, and then using entropy conservation of the reversible sub-system to derive an auxiliary elliptic equation. A remapping phase based on Lloyd iterations is applied to improve the mesh quality, while preserving the Lagrangian paradigm as much as possible. The final method, called SILVA (Semi-Implicit Lagrangian Voronoi Approximation), is validated in a variety of test cases that feature diverse Mach numbers, shocks and multi-phase flows.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"289 ","pages":"Article 106530"},"PeriodicalIF":2.5,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147867","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":"Development of a detailed surface chemistry framework in DSMC","authors":"Krishnan Swaminathan Gopalan ,&nbsp;Arnaud Borner ,&nbsp;Kelly A. Stephani","doi":"10.1016/j.compfluid.2024.106525","DOIUrl":"10.1016/j.compfluid.2024.106525","url":null,"abstract":"<div><div>A generalized finite-rate surface chemistry framework incorporating a comprehensive list of reaction mechanisms is developed and implemented into the direct simulation Monte Carlo (DSMC) solver SPARTA. The various mechanisms include adsorption, desorption, Langmuir-Hinshelwood, Eley-Rideal, Collision Induced, condensation, sublimation, etc. The approach is to stochastically model the various competing reactions occurring on a set of active sites. Both gas-surface and pure-surface reaction mechanisms are included; and the framework also encompasses catalytic or surface altering mechanisms involving the participation of the bulk-phase species. A general formulation where each surface can have multiple phases and different sites is adopted. Expressions for the microscopic parameters of reaction probabilities and frequencies that are required for DSMC are derived from the surface properties and macroscopic parameters such as rate constants, sticking coefficients, etc. This framework also presents physically consistent procedures to accurately compute the reaction probabilities and frequencies in the case of multiple reactions. The result is a modeling tool with a wide variety of surface reactions characterized via user-specified reaction rate constants, surface properties and input parameters. Finally, the framework implementation is verified for test cases with analytical solutions.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"292 ","pages":"Article 106525"},"PeriodicalIF":2.5,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578246","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}