Numerical analysis for wake flow field of Ahmed model based on a nonlinear-LRN/DES turbulence model

Zheng, Le Dian; Yang, Yi; Qiang, Guang Lin; Gu, Zhengqi

doi:10.1108/hff-06-2021-0438

Cited by 4 publications

(2 citation statements)

References 56 publications

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“…Several turbulence models have been introduced and modified for use in automobile aerodynamics (Han, 1989;Guilmineau, 2008;Speziale et al, 1991;Kapadia et al, 2004;Guilmineau et al, 2013). Notably, the results calculated with the k-« model improved by Gu et al ( , 2016Gu et al ( , 2022 closely align with experimental data. In addition to turbulence models, simplification of the automobile model, calculation domain, boundary conditions, grids, and discretization scheme also significantly influence simulation accuracy.…”

Section: Introductionmentioning

confidence: 60%

Research on precise and standardized numerical simulation strategy for vehicle aerodynamics

Chen,

Liu,

et al. 2024

HFF

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Purpose The purpose of this study is to propose a precise and standardized strategy for numerically simulating vehicle aerodynamics. Design/methodology/approach Error sources in computational fluid dynamics were analyzed. Additionally, controllable experiential and discretization errors, which significantly influence the calculated results, are expounded upon. Considering the airflow mechanism around a vehicle, the computational efficiency and accuracy of each solution strategy were compared and analyzed through numerous computational cases. Finally, the most suitable numerical strategy, including the turbulence model, simplified vehicle model, calculation domain, boundary conditions, grids and discretization scheme, was identified. Two simplified vehicle models were introduced, and relevant wind tunnel tests were performed to validate the selected strategy. Findings Errors in vehicle computational aerodynamics mainly stem from the unreasonable simplification of the vehicle model, calculation domain, definite solution conditions, grid strategy and discretization schemes. Using the proposed standardized numerical strategy, the simulated steady and transient aerodynamic characteristics agreed well with the experimental results. Originality/value Building upon the modified Low-Reynolds Number k-e model and Scale Adaptive Simulation model, to the best of the authors’ knowledge, a precise and standardized numerical simulation strategy for vehicle aerodynamics is proposed for the first time, which can be integrated into vehicle research and design.

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Section: Introductionmentioning

confidence: 60%

Research on precise and standardized numerical simulation strategy for vehicle aerodynamics

Chen,

Liu,

et al. 2024

HFF

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“…A SIMPLE algorithm was used for the numerical calculations. An IPN cloud explosion is a complex gas–liquid two-phase reaction process, which obeys the following basic equations (Jiang et al , 2016; Khanlari et al , 2022; Liu and Zhang, 2018, 2020; Song and Zhang, 2018, 2019; Zheng et al , 2022):…”

Section: Computational Models and Methodsmentioning

confidence: 99%

Explosion behaviors of IPN/air mixture at high temperature and high pressure

Wan

Wen²,

Zhang³

2022

HFF

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Purpose The reaction dynamics of combustible clouds at high temperatures and pressures are a common form of energy output in aerospace and explosion accidents. The cloud explosion process is often affected by the external initial conditions. This study aims to numerically study the effects of airflow velocity, initial temperature and fuel concentration on the explosion behavior of isopropyl nitrate/air mixture in a semiconstrained combustor. Design/methodology/approach The discrete-phase model was adopted to consider the interaction between the gas-phase and droplet particles. A wave model was applied to the droplet breakup. A finite rate/eddy dissipation model was used to simulate the explosion process of the fuel cloud. Findings The peak pressure and temperature growth rate both decrease with the increasing initial temperature (1,000–2,200 K) of the combustor at a lower airflow velocity. The peak pressure increases with the increase of airflow velocity (50–100 m/s), whereas the peak temperature is not sensitive to the initial high temperature. The peak pressure of the two-phase explosion decreases with concentration (200–1,500 g/m3), whereas the peak temperature first increases and then decreases as the concentration increases. Practical implications Chain explosion reactions often occur under high-temperature, high-pressure and turbulent conditions. This study aims to provide prevention and data support for a gas–liquid two-phase explosion. Originality/value Sustained turbulence is realized by continuously injecting air and liquid fuel into a semiconfined high-temperature and high-pressure combustor to obtain the reaction dynamic parameters of a two-phase explosion.

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Assessment of nonlinear-low Reynolds number/detached eddy simulation turbulence model for wake flow field simulation of a realistic automotive model

Yang

Zheng

2023

Physics of Fluids

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Since the results of wake flow simulation with commonly used turbulence models are unsatisfactory, by introducing a nonlinear Reynolds stress term and combining the DES (Detached Eddy Simulation) model, this paper further validates the nonlinear-LRN (Low Reynolds Number)/DES turbulence model which can predict flow separation and reattachment phenomenon more accurately. This model was verified by a wall-mounted hump flow case and was applied to the time-averaged and transient flow field structure analysis of a realistic automotive model with several widely used turbulence models. These simulation results were compared with the experimental data, indicating that nonlinear-LRN/DES model gives better agreements with the experiment and can predict the automobile wake flow structures and aerodynamic characteristics more accurately. Furthermore, the performance of the nonlinear-LRN/DES model in mesh with different refinement are compared, concluding that the new proposed model can obtain high accuracy in coarse mesh.

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Numerical analysis for wake flow field of Ahmed model based on a nonlinear-LRN/DES turbulence model

Cited by 4 publications

References 56 publications

Research on precise and standardized numerical simulation strategy for vehicle aerodynamics

Research on precise and standardized numerical simulation strategy for vehicle aerodynamics

Explosion behaviors of IPN/air mixture at high temperature and high pressure

Assessment of nonlinear-low Reynolds number/detached eddy simulation turbulence model for wake flow field simulation of a realistic automotive model

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