HYDROTHERMAL BEHAVIOR OF FLUID FLOW AND HEAT TRANSFER THROUGH A BENDING SQUARE CHANNEL

The numerous applications in medical fields as well as in industrial areas have drawn substantial attention of the researchers to study the fluid flow and heat transfer (HT) through a bent duct. The present paper demonstrates a spectral-based numerical study of 2D flow in a bent square geometry for various curvature ratios. The numerical calculation has been conducted over Dn, and the curvature ranges from 0.001 to 0.5. The horizontal walls are thermally different where the bottom wall is heated while the ceiling wall cooled, the vertical walls being thermally insulated. After an extensive investigation, we found two branching structures of the solution, each consisting of two branches with 2- to 8-vortex solutions for small and medium curvatures while three branches of solution structure for large curvature. The instability of the flow is then calculated by performing time-evolution (TEv) analysis and by sketching the phase-space (PS) of the solutions. This study also demonstrates that the HT is significantly boosted with the effect of secondary flows (SF) and the increasing secondary vortices boost heat transfer more effectively than other physically realizable solutions.