Title: Numerical investigation of wake dynamics and heat transfer in MHD flows around confined triangular prisms Show Chinese title

Title: MHD流中受限三角棱柱尾流动力学和传热的数值研究

Abstract: This study numerically investigates the flow evolution and heat transfer characteristics of an electrically conducting fluid over triangular prisms confined between two parallel plates with a heated bottom plate under the influence of a magnetic field. The research focuses on the three-dimensional behavior of MHD flows at low Hartmann numbers ($Ha$), exploring how obstacle orientation and mixed convection influence flow dynamics and heat transfer. Three-dimensional simulations are performed using an in-house MHD solver in OpenFOAM at a constant channel height based Reynolds number ($Re_{h}=600$). The combined effects of Richardson number ($Ri$) and $Ha$ on wake dynamics and heat transfer are analyzed for three triangular prism orientations. The results reveal that increasing $Ha$ promotes flow two-dimensionality, while higher $Ri$ enhances three-dimensionality. Three wake instability modes (Mode A, B, and C) are identified. Orientation 2 exhibits the lowest mean drag coefficient at $Ha=0$, $Ri=5$, while the highest mean lift coefficient is observed at $Ha=0$, $Ri=0$. Orientation 3 achieves the highest heat transfer rate, with an average Nusselt number of $21.05$ at $Ha=25$, $Ri=5$, and consistently outperforms the other orientations in heat transfer across various $Ha$ and $Ri$ conditions. These findings highlight the strong coupling between wake dynamics and heat transfer, offering insights for optimizing MHD flows in practical applications. Show Chinese abstract

Abstract: 本研究通过数值方法探讨了在磁场影响下，受限于两块平行板之间且底部平板加热的三角棱柱上方导电流体的流动演化和传热特性。 该研究重点研究低哈特曼数（$Ha$）下MHD流动的三维行为，探讨障碍物取向和混合对流如何影响流动动力学和传热。 在恒定通道高度基于雷诺数（$Re_{h}=600$）下，使用自编的MHD求解器在OpenFOAM中进行三维模拟。 分析了里查德森数（$Ri$）和$Ha$对三种三角棱柱取向下的尾流动力学和传热的综合影响。 结果表明，增加$Ha$会促进流动的二维性，而更高的$Ri$会增强三维性。 识别出三种尾流不稳定性模式（模式A、B和C）。 方向2在$Ha=0$，$Ri=5$时表现出最低的平均阻力系数，而在$Ha=0$，$Ri=0$时观察到最高的平均升力系数。 方位3实现了最高的传热速率，平均努塞尔数为$21.05$在$Ha=25$，$Ri=5$，并且在各种$Ha$和$Ri$条件下始终优于其他方位的传热性能。 这些发现突显了尾流动力学与传热之间的强耦合关系，为优化实际应用中的磁流体动力学流动提供了见解。