Computers & Fluids最新文献

{"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":"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}

{"title":"Numerical investigation on the end effects of the flow past a finite rotating circular cylinder with two free ends","authors":"Qiliang Liu,&nbsp;Shuguang Gong,&nbsp;Haishan Lu,&nbsp;Guilan Xie,&nbsp;Zhijian Zuo","doi":"10.1016/j.compfluid.2024.106475","DOIUrl":"10.1016/j.compfluid.2024.106475","url":null,"abstract":"<div><div>This paper studies the impact of the aspect ratio and free end shape on the end effects in the flow past a rotating circular cylinder with two flat, radiused, hemispherical, and conical ends, using the large eddy simulation method at a Reynolds number of <span><math><mrow><mn>4.6</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mn>4</mn></msup></mrow></math></span>. The aspect ratio in the range of 6–30 and the rotation rate in the range of 0–3, are investigated. The results show that the mean drag coefficient initially decreases slightly before rapidly increasing with the rotation rate, with a critical rotation rate that rises from 1 to 1.5 as the aspect ratio increases from 6 to 30. In contrast, the mean lift coefficient increases with both the rotation rate and the aspect ratio. When the rotation rate increases and the aspect ratio decreases, the differences between the aerodynamic coefficients of the four end shapes become more pronounced. The flat end results in the highest mean drag and lift coefficients, while the hemispherical end yields the lowest ones. In addition, when the rotation rate increases, the alternate shedding vortices shift to the opposite side. They even disappear and increase the elongated streamwise vortices. Due to the combined impacts of the rotation and end effects, large-scale tip vortices are formed, significantly altering the wake structure. The intense rotation effect results in expanding the strong influence region of the end effects and shrinking (or even removing) the weak influence region.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"285 ","pages":"Article 106475"},"PeriodicalIF":2.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657442","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":"On correctly evaluating orders of truncation error for node-centered edge-based schemes","authors":"Cosimo Tarsia Morisco,&nbsp;Hiroaki Nishikawa","doi":"10.1016/j.compfluid.2024.106470","DOIUrl":"10.1016/j.compfluid.2024.106470","url":null,"abstract":"<div><div>In this short note, we present a simple analysis to show that an observed order of truncation error on a regular grid can change, if not correctly evaluated, depending on the choice of the norm and also on the discretization scheme. For a second-order scheme, it can be first order, second order, or anywhere in between. Using the node-centered edge-based discretization as an example, we provide a guide on how to evaluate the order of truncation error correctly: one should evaluate it separately for a set of nodes, where the residual stencil is symmetric and the same at every node, and the rest of nodes.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"285 ","pages":"Article 106470"},"PeriodicalIF":2.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657443","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":"Non-inertial computational framework for long-distance shock-driven object dynamics","authors":"Dagao Wang ,&nbsp;Guilai Han ,&nbsp;Meikuan Liu ,&nbsp;Zongxian Li","doi":"10.1016/j.compfluid.2024.106474","DOIUrl":"10.1016/j.compfluid.2024.106474","url":null,"abstract":"<div><div>In the realm of dynamic separation problems, the motion of a body triggered by shock interactions is a common phenomenon. This is particularly important in terms of the safe separation of two-stage-to-orbit vehicles, where the motion must remain stable despite long-distance disturbances from shock waves. The flow field in these cases is complex, marked by interactions between hypersonic shock waves and a moving boundary. This leads to significant unsteady effects due to the body's translation and rotation over extended distances. Existing simulation techniques fall short in rapidly and accurately predicting the aerodynamic force and thermal properties for these problems, largely due to the overwhelming computational demands that result from oversize computational domains and the necessity of grid deformation. This paper presents a novel non-deforming grid method to address these challenges. The central concept is to anchor the reference frame to the moving object itself and to approach the problem from a non-inertial frame perspective. This accounts for the motion of the object solely via the inertial source term, circumventing the complexities of mesh manipulation typically required to link flow and motion equations. The moving shock boundary is designed to be closely compatible with selected shock-captured schemes, which reduces non-physical oscillations compared to the traditional method of direct assembly with theoretical shock relations. Other boundary conditions and the solution process are also refined to specifically target the unsteady, shock-dominated flow. These modifications significantly alleviate the computational burden. The effectiveness of the proposed method is demonstrated through several test cases. To showcase the method's practical application, a scenario is simulated wherein an ellipse is dislodged from a wedge by an incident shock wave, covering a long distance. These tests confirm the method's feasibility in aerospace engineering problems.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"286 ","pages":"Article 106474"},"PeriodicalIF":2.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658460","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 improved pressure gradient method for viscous incompressible flows","authors":"Zhisong Li ,&nbsp;Ye Li","doi":"10.1016/j.compfluid.2024.106448","DOIUrl":"10.1016/j.compfluid.2024.106448","url":null,"abstract":"<div><div>The pressure gradient method solves the viscous incompressible flow with the pressure gradients, rather than the pressure, as unknown variables. Two variants of the pressure gradient method have been developed in the past but have not received much attention due to their unsatisfactory performance or implementation complexity. Based on the artificial compressibility concept, this study proposes an improved pressure gradient method. One distinct feature of this method is that it requires no pressure/pressure gradient boundary condition or special treatment on wall boundaries. An auxiliary variable is introduced to represent the velocity dilatation, greatly simplifying the spatial discretization and computational procedure. The mathematical formulations are elaborated and compared with the previous pressure gradient methods, followed by discussions of compatibility relationships, boundary condition setup, and an extension to a pressure Poisson-like equation. Four validation examples are performed for various flow scenarios, and the solutions and domain solenoidity are examined for each case. The study also compares associated computational methods, different pressure boundary conditions, and flow characteristics, demonstrating the benefits of the present method.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"285 ","pages":"Article 106448"},"PeriodicalIF":2.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657877","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":"Finite-rate and equilibrium study of graphite ablation under arc-jet conditions","authors":"Aleksander L. Zibitsker ,&nbsp;Joel A. McQuaid ,&nbsp;Eric C. Stern ,&nbsp;Grant E. Palmer ,&nbsp;Benjamin J. Libben ,&nbsp;Christoph Brehm ,&nbsp;Alexandre Martin","doi":"10.1016/j.compfluid.2023.106069","DOIUrl":"https://doi.org/10.1016/j.compfluid.2023.106069","url":null,"abstract":"<div><p>Arc-jet facilities play a primary role in recreating aerothermal conditions experienced by atmospheric entry vehicles and are widely used to test the performance of thermal protection materials. In this work, we utilize a developed coupled framework between an overset flow solver CHAMPS NBS-Cart, and a material solver KATS-MR to study the ablation of graphite under arc-jet conditions. We implement a 12-species gas phase model to accurately represent the air-carbon mixture, including argon species present in the flow. The gas phase is modeled with a two-temperature thermo-chemical non-equilibrium model without considering electronic and ionization effects. The gas-surface interactions are modeled with a newly developed air-carbon ablation model accounting for oxidation, nitridation, and recombination reactions. In addition, the model is augmented with carbon sublimation reactions experienced at high heating conditions. The chemical state at the surface is tightly coupled with the flow solver, resulting in the improved accuracy and effectiveness of the simulation. The coupled approach is applied to study two experimental test cases conducted at the IHF arc-jet facility at NASA Ames. The predicted results are validated against measured recession, surface, and in-depth temperatures and compared to the prediction of the uncoupled, equilibrium-based approach. Finally, the accuracy of the prediction is explored with respect to the environmental properties, such as the diffusion coefficient, and material thermal conductivity.</p></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"267 ","pages":"Article 106069"},"PeriodicalIF":2.8,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41227927","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":"Sidewall effects in laminar ramp induced shockwave boundary layer interactions","authors":"Raja Mangalagiri,&nbsp;Satya P. Jammy","doi":"10.1016/j.compfluid.2023.106063","DOIUrl":"https://doi.org/10.1016/j.compfluid.2023.106063","url":null,"abstract":"<div><p>Shock-wave boundary layer interactions (SWBLI) play a significant role in control surfaces and engine inlets. However, most simulations commonly assume span-periodic or 2D. Recent research conducted by Lusher and Sandham (2020) investigated the effects of sidewalls in impinging-type SWBLI (ISWBLI). This study’s focus is to numerically explore the influence of sidewalls in a three-dimensional context for ramp-induced SWBLI (RSWBLI). First a 2D ramp-induced separated boundary layer interaction with a ramp angle of <span><math><mrow><mn>6</mn><mo>.</mo><mn>8</mn><mo>°</mo></mrow></math></span> was identified. This configuration produced the same pressure rise and separation characteristics as those reported by Katzer (1989) at a Mach number of 2 and an impinging Reynolds number of <span><math><mrow><mn>3</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup></mrow></math></span>. Subsequently, the sidewall was introduced for Aspect Ratio 1 and the results were analysed. From the analysis it was found out that the separation length for the 3D case is 14% greater than that observed in the 2D simulation. Upon comparison with the ISWBLI study of Lusher and Sandham (2020), it was found that (a) the sidewall and central separation are connected in RSWBLI, contrasting with ISWBLI, (b) the extent of sidewall separation in RSWBLI is very limited compared to the impingement interaction, and (c) RSWBLI displays characteristics closer to an owl-like separation of second kind, whereas in ISWBLI exhibits characteristics of the first kind of separation. Even though having identical shock-strength and separation length for both R &amp; I SWBLI in 2D configuration, the introduction of sidewall resulted in a distinct topology and dynamics of interaction .</p></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"267 ","pages":"Article 106063"},"PeriodicalIF":2.8,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41227926","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":"Dual transition scheme on k-equation model","authors":"M.M. Rahman","doi":"10.1016/j.compfluid.2023.106068","DOIUrl":"https://doi.org/10.1016/j.compfluid.2023.106068","url":null,"abstract":"<div><p>The proposed model integrates two transition mechanisms into the turbulent kinetic energy (<span><math><mi>k</mi></math></span>-equation) turbulence framework, assisted by transition representatives. These include a “flow-structure-adaptive” stress-intensity parameter, which induces the pre-transitional/pseudo-laminar state before transition, and an intermittency factor, which facilitates the prediction of flow transition onset and completion with a feasible growth rate and a logical transition length. The algebraic transition model introduces new functions and correlations, which are based on theoretical and experimental evidence. These elements stimulate multiple transition phenomena in a suitable and credible way due to their reliance on local flow information for initiating and controlling the transition growth rate. With the employment of an algebraic closure for the dissipation rate, the <span><math><mi>k</mi></math></span>-equation directly anticipates the free-stream turbulence intensity instead of the free-stream “eddy-to-laminar” viscosity ratio (<span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>μ</mi><mi>∞</mi></mrow></msub></math></span>). This approach avoids the “trial-and-error” inconsistency typically associated with most correlation-based and physics-based transition models when initiating appropriate computations. The independence of the algebraic transition model from <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>μ</mi><mi>∞</mi></mrow></msub></math></span> offers substantial benefits in predictive capability over traditional transition models. However, the quality of performance might fluctuate, contingent on the closure approximations adopted. This detail is of immense importance for accurately depicting the pertinent physical characteristics of the flow, such as bypass, natural, and separation-induced transitions. Numerical results indicate that the current model, whether equipped with algebraic transition additives or not, aligns well with both existing experimental data and commonly used transition and non-transition models. The new transition model has decent agreement with the transitional boundary layer on a flat plate, and transitional flow over an airfoil with laminar and turbulent separation bubbles.</p></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"267 ","pages":"Article 106068"},"PeriodicalIF":2.8,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41227929","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}