非定常浅水流动中热水对流-扩散过程的数值模拟

Numerical Simulation for the Hot-Water Convection-Diffusion Process in an Unsteady Shallow Flow

本文从深度平均的连续、动量和热输运方程出发,应用深度平均的k-ε湍流模式,对非定常浅水明渠流动中侧向排入热水形成的速度场和温度场作了数值模拟。在定常情况下,本文的计算结果表明:当水深较浅或热水排放动量较大时,放弃“刚盖假设”对于提高预计精度是必要的。非定常情况的计算结果与采用准定常假设的计算结果作了比较。这一比较表明:即使以最大主流速度定义的Strouhal数很小,在憩流前后的一段时间内,流动非定常性对速度场和温度场的影响仍是显著的。

Using the depth-averaged k-e turbulence model, the depth-averaged equations of continuity, momentum and heat transport are solved numerically for the near field of hot-water side discharges into an unsteady shallow open-channel flow. In the steady case, the computational results demonstrate that when the flow is shallower the discharging momentum is relatively large, the 'rigid lid' approximation should be discarded. In the unsteady case, the computational results have been compared with that of a quasi-steady prediction. It is shown that although the Strouhal number defined by the maximum velocity of the main flow is small, the velocity and temperature fields immediately before and after the rest state of the main flow are significantly influenced by the unsteady-flow effect.