Numerical investigation of the unsteady fluid force induced in the annular diffuser by the oscillating inner cylinder

A numerical simulation technique with the moving grid system has been developed for the flow analysis of the boundary oscillating problem. This technique is applied to flow simulations in an annular diffuser with an oscillating inner cylinder. Two- and three-dimensional analyses have been examined and the unsteady flow-induced forces have been estimated. A negative damping force which may promote vibrations can be also predicted in some conditions.