湍流热对流系统中粗糙壁面对流动结构的影响

自然界中存在的热对流现象大部分都具有粗糙边界, 研究粗糙壁面 Rayleigh-Bénard(RB)湍流热对流对理解湍流传热和流动结构具有重要的理论价值和实际意义. 采用数值模拟的方法研究二维粗糙壁面对 RB 湍流热对流流动结构的影响, 主要参数 Rayleigh 数(Ra)和 Prandtl 数(Pr)分别为 10$^{7}\le $Ra$\le $10$^{9}$和 $Pr = 0.7$. 计算中采用的粗糙元形状为等腰直角三角形. 结果表明:粗糙元对大尺度环流的抑制作用与粗糙元对羽流的生成和二次涡的促进作用相互竞争, 导致 Reynolds 数(Re)变化复杂, Ra 数与 Re 数的标度律关系异常.

Effect of surface roughness on flow structures of turbulent Rayleigh-Bénard convection

Most thermal convection phenomena in nature have rough boundaries. Thus, the study of Rayleigh-Bénard (RB) turbulent thermal convection on rough surfaces is theoretically and practically significant in understanding turbulent heat transfer and flow structures. In this study, the effect of two-dimensional rough surfaces on flow structures of turbulent RB convection is investigated through numerical simulations. The main parameters, the Rayleigh number (Ra) and Prandtl number (Pr), were 10$^{7 }\le $ $Ra\le 10^{9}$ and $Pr = 0.7.$ An isosceles right-angle triangle of the rough element shape was used for calculations. The results showed that the inhibition of the rough element on the large-scale circulation and the enhancement of the rough element on the plume generation and secondary vortices led to the complexity of the Reynolds number (Re) variation and the abnormal scaling relationship between Ra and Re.