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由于目前用于求解湍流自然对流流动与传热的k-ε模型在应用过程中存在不足,结合高雷诺数k-ε模型需要借助壁面函数法来确定壁面上相关参数值和低雷诺数k-ε模型在近壁区布置更多节点以便获得粘性底层详细信息的特点,重新定义了湍流普朗特数σt的计算式,提出了一种修正的k-ε新模型;利用该模型对封闭方腔内的湍流自然对流流动与传热进行了数值分析。结果表明:与文献中数值模拟结果相比,当108≤Ra≤1014时本文模型所得壁面平均努塞尔特数更接近文献中的实验值,与实验值之间的相对误差在8%以内;壁面的局部努塞尔特数与文献中的实验值吻合得较好。这说明本文模型用于求解封闭腔内湍流流动与传热问题是合适的,比其它湍流模型更能准确地描述封闭腔内湍流自然对流换热中边界层发展与壁面传热特性之间的内在联系。
Due to the shortcomings of k-ε model used to solve the turbulent natural convection and heat transfer, the wall function method needs to be used to determine the relevant parameters of the wall and the low Reynolds number k- ε model, more nodes are arranged on the near wall to obtain the details of the viscous underlayer, and the formula of turbulent Prandtl number σt is redefined. A new modified k-ε model is proposed. By using this model, Numerical simulation of turbulent flow and heat transfer in cavity was carried out. The results show that compared with the numerical simulation results in the literature, the average wall Nusselt number obtained by this model is closer to the experimental value in the literature when the value of 108 ≤ Ra ≤ 1014, and the relative error with the experimental value is within 8% The local Nusselt number of the wall is in good agreement with the experimental data in the literature. This shows that the proposed model is suitable for the problem of turbulent flow and heat transfer in a closed cavity. It is more accurate than other turbulence models to describe the inherent relationship between the boundary layer development and wall heat transfer characteristics in turbulent natural convection contact.