Numerical Investigation of Laminar Forced Convection of Shear-Thinning Fluids Through Alternating Dual Orifices

A numerical investigation is conducted to study two-dimensional laminar forced convection of shear-thinning fluids flowing through a pipe equipped with alternating dual orifices under isothermal wall conditions analysed over a wide range of pipe Reynolds number, (1 ≤ Re ≤ 100) for a fixed orifice plate thickness ratio, (γ = 1/16) and two orifice-to-pipe diameter ratio, (β = 0.2 and 0.8).The rheological behaviour of the fluid is described using the shear-thinning fluids with the power-law index (n) varying from 0.2 to 1, encompassing strongly shear-thinning to Newtonian fluids.The flow and heat transfer characteristics are analysed in terms of pressure coefficient, streamline patterns, velocity contours, centreline velocity, and local Nusselt number.The results indicate that the formation of vena contracta downstream of the upstream orifice is independent of the presence of the second orifice but is strongly influenced by the orifice diameter ratio.Conversely, the occurrence of vena contracta downstream of the second orifice depends on the diameter ratio.While the downstream flow structure resembles that of a single-orifice configuration, the inter-orifice region exhibits a unique flow pattern characterized by a donut-shaped vortex near the wall and a jet-like core flow.The extent of vortex formation increases with increasing Reynolds number and power-law index for Pr = 0.7, highlighting the combined influence of inertia and shearthinning behaviour on the thermo-hydrodynamic performance.