Computers & Fluids最新文献

英文中文

Assessment of thermochemical models on nonequilibrium flowfield and radiation in shock-heated nitrogen

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-26 DOI: 10.1016/j.compfluid.2024.106533

Yuzhe Zhang , Qizhen Hong , Xiaoyong Wang , Chao Yang , Quanhua Sun

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.

{"title":"Assessment of thermochemical models on nonequilibrium flowfield and radiation in shock-heated nitrogen","authors":"Yuzhe Zhang , Qizhen Hong , Xiaoyong Wang , Chao Yang , 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 N<sub>2</sub>, and predissociation of the N<sub>2</sub>(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}

引用次数: 0

Hybrid parallel discrete adjoints in SU2

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-24 DOI: 10.1016/j.compfluid.2024.106528

Johannes Blühdorn , Pedro Gomes , Max Aehle , Nicolas R. Gauger

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.

引用次数: 0

A hybrid phase field-volume of fluid method for simulating dynamically evolving interfaces in multiphase flows

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-22 DOI: 10.1016/j.compfluid.2024.106536

Atin Kumar Dolai , Vinod Pandey , Gautam Biswas , Suman Chakraborty

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.

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引用次数: 0

Semi-implicit quasi-Lagrangian Voronoi approximation for compressible viscous fluid flows

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-22 DOI: 10.1016/j.compfluid.2024.106530

Ondřej Kincl , Ilya Peshkov , Walter Boscheri

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.

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引用次数: 0

A novel symmetric flux limiter scheme for unstructured grids

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-19 DOI: 10.1016/j.compfluid.2024.106531

Xin Gao , Xiaomin Zhang , Qiong Wu , Zhipeng Zhao , Yang Liu , Junfeng Ou , Jian Liu

An appropriate flux limiter scheme and r-factor algorithm are crucial for convective discretization processes in computational fluid dynamics. To balance the accuracy, convergence, and stability of numerical simulations, a new nonlinear flux limiter scheme satisfying symmetry and smoothness is constructed based on the total variation decreasing (TVD) criterion. In addition, a new r-factor algorithm is proposed to enable implementation of TVD schemes on unstructured grids, which is achieved by employing a more reasonable reconstruction method for far upwind node position and an interpolation method requiring more upwind information. Benchmarking results for convection-dominated problems on structured and unstructured grids show that the new TVD scheme exhibits superior convergence and stability compared with classical TVD schemes, while maintaining high precision, and achieves a balance between compressibility and diffusion. Meanwhile, the new r-factor algorithm has better performance in terms of overall accuracy and convergence compared with other existing algorithms, demonstrating its potential for extensive application.

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引用次数: 0

Corrigendum to “A compressible multiphase Mass-of-Fluid model for the simulation of laser-based manufacturing processes” [Computers & Fluids 268 (2024) 106109]

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-19 DOI: 10.1016/j.compfluid.2024.106529

Constantin Zenz , Michele Buttazzoni , Tobias Florian , Katherine Elizabeth Crespo Armijos , Rodrigo Gómez Vázquez , Gerhard Liedl , Andreas Otto

引用次数: 0

Quantum algorithm for collisionless Boltzmann simulation of self-gravitating systems

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-19 DOI: 10.1016/j.compfluid.2024.106527

Soichiro Yamazaki , Fumio Uchida , Kotaro Fujisawa , Koichi Miyamoto , Naoki Yoshida

The collisionless Boltzmann equation (CBE) is a fundamental equation that governs the dynamics of a broad range of astrophysical systems from space plasma to star clusters and galaxies. It is computationally expensive to integrate the CBE directly in a multi-dimensional phase space, and thus the applications to realistic astrophysical problems have been limited so far. Recently, Todorova & Steijl (2020) proposed an efficient quantum algorithm to solve the CBE with significantly reduced computational complexity. We extend the algorithm to perform quantum simulations of self-gravitating systems, incorporating the method to calculate gravity with the major Fourier modes of the density distribution extracted from the solution-encoding quantum state. Our method improves the dependency of time and space complexities on

N_{v}

, the number of grid points in each velocity coordinate, compared to the classical simulation methods. We then conduct some numerical demonstrations of our method. We first run a 1+1 dimensional test calculation of free streaming motion on 64 × 64 grids using 13 simulated qubits and validate our method. We then perform simulations of Jeans collapse, and compare the result with analytic and linear theory calculations. It will thus allow us to perform large-scale CBE simulations on future quantum computers.

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引用次数: 0

From simplex to mixed element: Extension of a vertex-centered discretization, focus on accuracy analysis and 3D RANS applications

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-19 DOI: 10.1016/j.compfluid.2024.106526

Cosimo Tarsia Morisco , Frédéric Alauzet , Guillaume Puigt

Standard unstructured-grid CFD simulations generally rely on a cell-centered Finite Volume discretization applied to mixed-element grids. The interest in such approach is using elements that are aligned along a privileged direction in the region close to the boundary, and at the same time unstructured elements near complex geometrical details or in farfield regions. This paper proposes a novel version of the mixed Finite Element/Finite Volume approximation (Debiez and Dervieux 2000), which is a vertex-centered method known to produce second-order accurate solutions even on highly anisotropic adapted meshes composed of simplex elements (i.e., triangles and tetrahedra) (Alauzet and Loseille, 2010; Barral et al., 2017; Alauzet et al., 2018; Belme et al., 2019). The extension of this approach for two-dimensional mixed-element meshes was proposed in Tarsia Morisco et al. (2024) and involves the APproximated Finite Element -APFE- method (Puigt et al., 2010) to discretize diffusion. In this work we make the definitive step forward to handle three-dimensional mixed-element meshes: designing a second-order accurate scheme for smooth meshes involving tetrahedra, prisms and pyramids.

The present work focuses on two key aspects. One concerns the 3D extension of the APFE method. A detailed error analysis of this vertex-centered approach is provided for prisms and pyramids. The second ingredient deals with an innovative algorithm to compute the truncation error for linear problems. In contrast to usual methods, the one proposed here permits to compute exactly the coefficients related to each terms of error for any mesh, and can be implemented in any solver with a low development effort.

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引用次数: 0

A critical comparison of the implementation of granular pressure gradient term in Euler–Euler simulation of gas–solid flows

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-18 DOI: 10.1016/j.compfluid.2024.106523

Yige Liu , Mingming He , Jianhua Chen , Wen Li , Bidan Zhao , Ji Xu , Junwu Wang

Numerical solution of Euler–Euler model using different in-house, open source and commercial software can generate significantly different results, even when the governing equations and the initial and boundary conditions are exactly same. Unfortunately, the underlying reasons have not been identified yet. In this article, three methods for calculating the granular pressure gradient term are presented for two-fluid model of gas–solid flows and implemented implicitly or explicitly into the solver in OpenFOAM®: Method

I

assumes that the granular pressure gradient is equal to the elastic modulus plus the solid concentration gradient; Method

I I

directly calculates the gradient using a difference scheme; Method

I I I

, which is proposed in this work, calculates the gradient as the sum of two partial derivatives: one related to the solid volume fraction and the other related to the granular energy. Obviously, only Methods

I I

and

I I I

are consistent with kinetic theory of granular flow. It was found that the difference between all methods is small for bubbling fluidization. While for circulating fluidization, both Methods

I I

and

I I I

are capable of capturing non-uniform structures and producing superior results over Method

I

. The contradictory conclusions made from the simulation of different fluidization regimes is due to the different contribution of the term related to the granular energy gradient. Present study concludes that the implementation method of granular pressure gradient may have a significant impact on the hydrodynamics of gas–solid flows and is probably a key factor contributing to the observed differences between different simulation software.

{"title":"A critical comparison of the implementation of granular pressure gradient term in Euler–Euler simulation of gas–solid flows","authors":"Yige Liu , Mingming He , Jianhua Chen , Wen Li , Bidan Zhao , Ji Xu , Junwu Wang","doi":"10.1016/j.compfluid.2024.106523","DOIUrl":"10.1016/j.compfluid.2024.106523","url":null,"abstract":"<div><div>Numerical solution of Euler–Euler model using different in-house, open source and commercial software can generate significantly different results, even when the governing equations and the initial and boundary conditions are exactly same. Unfortunately, the underlying reasons have not been identified yet. In this article, three methods for calculating the granular pressure gradient term are presented for two-fluid model of gas–solid flows and implemented implicitly or explicitly into the solver in OpenFOAM®: Method <span><math><mi>I</mi></math></span> assumes that the granular pressure gradient is equal to the elastic modulus plus the solid concentration gradient; Method <span><math><mrow><mi>I</mi><mi>I</mi></mrow></math></span> directly calculates the gradient using a difference scheme; Method <span><math><mrow><mi>I</mi><mi>I</mi><mi>I</mi></mrow></math></span>, which is proposed in this work, calculates the gradient as the sum of two partial derivatives: one related to the solid volume fraction and the other related to the granular energy. Obviously, only Methods <span><math><mrow><mi>I</mi><mi>I</mi></mrow></math></span> and <span><math><mrow><mi>I</mi><mi>I</mi><mi>I</mi></mrow></math></span> are consistent with kinetic theory of granular flow. It was found that the difference between all methods is small for bubbling fluidization. While for circulating fluidization, both Methods <span><math><mrow><mi>I</mi><mi>I</mi></mrow></math></span> and <span><math><mrow><mi>I</mi><mi>I</mi><mi>I</mi></mrow></math></span> are capable of capturing non-uniform structures and producing superior results over Method <span><math><mi>I</mi></math></span>. The contradictory conclusions made from the simulation of different fluidization regimes is due to the different contribution of the term related to the granular energy gradient. Present study concludes that the implementation method of granular pressure gradient may have a significant impact on the hydrodynamics of gas–solid flows and is probably a key factor contributing to the observed differences between different simulation software.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"288 ","pages":"Article 106523"},"PeriodicalIF":2.5,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143138648","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}

引用次数: 0

Incompressible Navier–Stokes solve on noisy quantum hardware via a hybrid quantum–classical scheme

IF 2.5 3区工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers & Fluids

Pub Date : 2024-12-18 DOI: 10.1016/j.compfluid.2024.106507

Zhixin Song , Robert Deaton , Bryan Gard , Spencer H. Bryngelson

Partial differential equation solvers are required to solve the Navier–Stokes equations for fluid flow. Recently, algorithms have been proposed to simulate fluid dynamics on quantum computers. Fault-tolerant quantum devices might enable exponential speedups over algorithms on classical computers. However, current and foreseeable quantum hardware introduce noise into computations, requiring algorithms that make judicious use of quantum resources: shallower circuit depths and fewer qubits. Under these restrictions, variational algorithms are more appropriate and robust. This work presents a hybrid quantum–classical algorithm for the incompressible Navier–Stokes equations. A classical device performs nonlinear computations, and a quantum one uses a variational solver for the pressure Poisson equation. A lid-driven cavity problem benchmarks the method. We verify the algorithm via noise-free simulation and test it on noisy IBM superconducting quantum hardware. Results show that high-fidelity results can be achieved via this approach, even on current quantum devices. Multigrid preconditioning of the Poisson problem helps avoid local minima and reduces resource requirements for the quantum device. A quantum state readout technique called HTree is used for the first time on a physical problem. Htree is appropriate for real-valued problems and achieves linear complexity in the qubit count, making the Navier–Stokes solve further tractable on current quantum devices. We compare the quantum resources required for near-term and fault-tolerant solvers to determine quantum hardware requirements for fluid simulations with complexity improvements.

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