粘弾性流体中での円柱の抗力特性

抄録

Drag forces on a circular cylinder placed in a rotating cylindrical annulus filled with a viscoelastic wormlike micellar fluid are measured using a load cell. The flow patterns are extracted from the PIV (particle image velocimetry) measurements of the flow fields around the circular cylinder. In viscoelastic fluids, shear waves can be propagated, and the viscoelastic Mach number M is defined as the ratio of the speed of an object in a fluid to the speed of shear waves in the fluid. In this study, the effect of viscoelastic Mach number on the drag characteristics of the circular cylinder is investigated. The results show that when the viscoelastic Mach number M > 1, an increase of drag over that expected from the growth rate at viscoelastic Mach numbers M < 1 is observed. From the results of PIV measurements, a dead water region is observed, which is formed symmetrically around the circular cylinder when M < 1 and behind the circular cylinder when M > 1. It plays an important role in the drag increase on a circular cylinder.