부산대학교 도서관

The flow of a UCM (Upper Convected Maxwell) fluid through a linear array of cylinders is numerically simulated using a finite-difference method, with a Cartesian mesh and the staggered variable arrangement to investigate the Deborah number effects on the flow behind the cylinders. The volume penalization method, one of the immersed boundary methods, represents solid bodies, and the periodic boundary condition is used to describe an infinite array of cylinders. The governing equations consist of the stream function-vorticity formulation of the momentum equation and the constitutive equations of the UCM fluid. Deborah number (De) is defined as the ratio of a characteristic relaxation time of the fluid to a characteristic time of the flow. As the Deborah number increases, the elastic forces become more significant, and three types of flow patterns are observed: the extension of shear layers with vortex shedding, the laminar-like flow with suppression of vortex shedding, and the reappearance of the vortical flow. In addition, in a similar fashion of magnetic reconnection in magnetohydrodynamics, the reconnection of the elastic stress is observed.