Steady and Unsteady Dynamics of Magneto-Nanofluidic Flow in a Bottom-Heated Top-Cooled Recto-Triangular Thermal System

This work numerically explores the evolution flow features during the journey through unsteady to steady dynamics in a magneto-nanofluidic thermal system of recto-triangular shape. This system, which is partially heated using the triangular surface and employs a top-cooling configuration, features an upper rectangular and a lower triangular part. The study addresses laminar flow for various Rayleigh numbers (Ra) up to 105 considering uniform magnetic fields at different inclination angles and utilizing a 0.1% nanoparticle concentration (fixed) CuO-water nanofluid along with a finite element-based solver. The results reveal the formation of multi-vortical structures with varying numbers of circulation cells. The most important observation is the transformation of cells from a four-cell configuration to a one-cell configuration, and finally to a two-cell configuration as Ra changes from 103 to 104 to 105 without a magnetic field. The one-cell structure sustains over a narrow range of Ra and is sensitive to the Hartmann number (Ha). The inclined magnetic fields have a severe impact on the flow structure. Starting from a quiescent state and progressing through the unsteady flow stages, the system rapidly reaches a steady state under different temperature differences (simulated by Ra), except for a few exceptions of Ra and Ha values. The analysis of the unsteady stages of flow development provides deeper insights into the dynamics of multi-cellular flows.