On Laminar Wakes Behind a Circular Cylinder in Stratified Fluids

Abstract

Finite-difference techniques based on boundary-fitted coordinates have been developed to study the flow of a stably stratified viscous fluid past a circular cylinder. A time-dependent approach is used and an implicit solution is applied in the implementation of vorticity-stream function formulation. All field equations are approximated using central differences and solved simultaneously at each time step by the SOR iteration. Results show that the stratification tends to retard the vortex shedding from the two sides of the cylinder and to narrow down the wake behind the cylinder. With increasing stratification, the drag exerted by the fluid on the cylinder at first decreases and then increases. These solutions also indicate that the periodic configurations of the oscillatory character of the wake flow decrease with the increase of stratification.