Experimental and Numerical Study of Flow over Rectangular Cavity

Abstract

This study investigates shear-thinning non-Newtonian fluid flow over a rectangular cavity using both experimental and numerical approaches. Small concentrations, varying between 0.25% and 1.0% of polyacrylamide (PAM) with high molecular weight, were used to form the non-Newtonian solution. In the experimental phase, Particle Image Velocimetry (PIV) was employed to obtain time-averaged velocity fields and recirculation characteristics. These experimental findings were compared with numerical simulations using Computational Fluid Dynamics (CFD) in which the fluid behavior was characterized using the Carreau rheological model. Excellent agreement was achieved between experimental and numerical results for velocity vectors, streamwise and transverse velocity contours, and vorticity distributions across Reynolds numbers ranging from 5 to 50. The structural flow changes within and in the vicinity of the rectangular cavity resulting from increasing Reynolds numbers are analyzed in detail, with particular emphasis on how the shearthinning properties influence vortex formation, recirculation zones, and velocity gradients.