THE HYDRODYNAMIC DAMPING FORCE ON A CYLINDER IN OSCILLATORY, VERY HIGH-REYNOLDS-NUMBER FLOWS

The time-dependent, attached, oscillatory, turbulent boundary-layer fl ow over a smooth circular cylinder is modelled. The problem is reduced to the solution of a number of analogous flat-plate problems, a techn ique that is applicable if the fluid particle amplitude is small compa red with the diameter of the cylinder. Each flat-plate problem is trea ted using an algebraic, two-layer, mixing-length turbulence model, mod ified to simulate effects at transitional Reynolds numbers, these modi fications being made with reference to existing results for flat plate s obtained experimentally and by direct numerical simulation. The drag (damping) force in phase with the flow velocity is obtained from the surface shear stress and boundary-layer displacement thickness distrib utions. This force is of practical importance in offshore engineering at very high Reynolds numbers, where there is a lack of experimental, theoretical or numerical data. (C) 1996 Elsevier Science Ltd.