Numerical investigation of wake dynamics and heat transfer in MHD flows around confined triangular prisms

TL;DR

This paper numerically explores how magnetic fields, obstacle orientation, and mixed convection influence wake behavior and heat transfer in MHD flows around confined triangular prisms, revealing key effects of these parameters on flow stability and thermal performance.

Contribution

It provides new insights into the combined effects of magnetic fields and obstacle orientation on wake dynamics and heat transfer in 3D MHD flows, using detailed numerical simulations.

Findings

Increasing Hartmann number promotes flow two-dimensionality.

Higher Richardson number enhances three-dimensional wake structures.

Orientation 3 yields the highest heat transfer rate with an average Nusselt number of 21.05.

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.