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Evaluation of LES sub-grid scale models and time discretization schemes for prediction of convection effect in a buoyant pool fire
Heat and Mass Transfer ( IF 1.7 ) Pub Date : 2020-10-10 , DOI: 10.1007/s00231-020-02952-4
Mohammad Safarzadeh , Ghassem Heidarinejad , Hadi Pasdarshahri

The identification of the type of regime has an essential effect on the selection of sub-grid scale and discretization methods, regarding the accuracy and computational time. In order to investigate the role of sub-grid scale and time discretization method in a pool fire modeling by the Large Eddy Simulation (LES), three sub-grid scales Smagorinsky, one-equation and Wall-Adapting Local Eddy-Viscosity (WALE) and three time discretization methods of first-order Euler method, second-order Crank Nicolson and backward second-order were investigated. The results indicate that WALE and one-equation sub-grid scale have an acceptable prediction, while Smagorinsky has a significant error with the experimental results. Different time discretization methods have little effects on the results of mean velocity and mean turbulent parameters of the pool fire. By considering the instantaneous distribution of parameters, all three methods perform similar results where the kinetic energy is less than 5 m2/s2. In areas where the perturbation is aggravated, the two second-order discretization methods have the same error with a little difference by the first-order Euler method. The accuracies of second-order methods are about 10% for the velocity prediction, compared to the experimental results, while the error of the Euler method is 15%.



中文翻译:

LES子网格规模模型和时间离散方案的评估,用于预测浮力水池火灾中的对流效应

在精度和计算时间方面,模式类型的确定对子网格规模的选择和离散化方法具有至关重要的作用。为了通过大涡模拟(LES)来研究子网格规模和时间离散化方法在水池火场建模中的作用,使用了三个子网格规模Smagorinsky,一方程组和适应墙的局部涡粘性(WALE)分别研究了一阶欧拉法,二阶Crank Nicolson和后向二阶三种时间离散方法。结果表明,WALE和一方程子网格规模具有可接受的预测,而Smagorinsky的实验结果有明显的误差。不同的时间离散方法对池火的平均速度和平均湍流参数的影响很小。2 /秒2。在扰动加剧的区域,两种二阶离散化方法具有相同的误差,而一阶欧拉方法的误差很小。与实验结果相比,二阶方法的速度预测精度约为10%,而欧拉方法的误差为15%。

更新日期:2020-10-11
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