Abstract
A numerical study of the mixing phenomenon by a rotating rigid flat plate inside a square enclosure is presented. The walls of the enclosure and the flat plate are impermeable. The flat plate is placed centrally with in the enclosure, it can rotate about its centroid axis and the thickness is negligible. The fluid is initially considered to be at rest at the initial concentration of the lower half of the enclosure as high concentration, while the upper half as low concentration. The influence of the non-dimensional length of the flat plate and frequency of the flat plate which is the function of the Reynolds number are numerically investigated. The governing equations are solved with finite difference method. It is observed that the numerical method can efficiently simulate the mixing phenomenon. From the results, it was found that the mixing of the concentration is more efficient by increasing the Reynolds number and the length of the flat plate and the shear force is increased with the Reynolds number increases.