Numerical simulations are conducted for steady flow striking a porous circular cylinder from various orientations in the mixed convection regime over wide ranges of the Reynolds number (5 ≤ Re ≤ 40), Darcy number (10⁻⁶ ≤ Da ≤ 10⁻²), and Richardson number (0 ≤ Ri < 7). The free-stream orientation is defined as an angle (α) between the directions of the free stream and the gravitational acceleration, varying from 90° to 180°. For 90° ≤ α < 180°, the recirculating wakes present an asymmetric structure under thermal buoyancy, which is more obvious for relatively permeable cases. The impact of α on this asymmetry is inextricably dependent on Re, Ri, and Da. Diverse wake structures are identified owing to the interaction between the free-stream orientation and the strength of thermal buoyancy. Two or three regimes with various wake behaviours are distinguished, including the two-recirculating-wake regime, the single-recirculating-wake regime, and the no-recirculating-wake regime. Thermal buoyancy suppresses the development of the recirculating wakes. Less thermal energy is required for the complete suppression of the recirculating wakes at smaller Re and larger Da. The heat transfer rate in terms of the average Nusselt number (Nu_ave) is enhanced when α increases, and the stimulative effect of thermal buoyancy on heat transfer at constant Re and Da is more pronounced at a higher α.

在雷诺数 (5 ≤ Re  ≤ 40)、达西数 (10 ^-6  ≤  Da ≤ 10 ^-2 ) 和大范围的混合对流状态中，针对从不同方向撞击多孔圆柱体的稳态流进行数值模拟 ，以及理查森数（0 ≤  Ri  < 7）。自由流方向定义为自由流方向与重力加速度之间的角度 (α)，从 90° 到 180° 不等。当90°≤α<180°时，再循环尾流在热浮力作用下呈现不对称结构，在相对渗透的情况下更为明显。α 对这种不对称性的影响不可避免地取决于Re、Ri和达。由于自由流方向和热浮力强度之间的相互作用，识别出不同的尾流结构。区分了具有不同尾流行为的两种或三种状态，包括二次循环唤醒状态、单循环唤醒状态和无循环唤醒状态。热浮力抑制了再循环尾流的发展。在较小的Re和较大的Da 下完全抑制再循环尾流所需的热能较少。当 α 增加时，以平均努塞尔数 ( Nu _ave ) 表示的传热速率增强，并且热浮力对恒定Re和Da在较高的 α 下更明显。