ポーラス状の外側部をもつ円柱まわりの流れの数値シミュレーション

The flow past a circular cylinder surrounded by a porous body was numerically investigated using a 2D-DNS code for various porosity Ct. We find strange wake structures of the cylinder-porous body. The wake flows are classified into three regimes. Regime I (Ct <1.0) : Karman vortex street from the inside solid cylinder is clearly formed. A pair of separated shear layers from the outside porous body surround the inside vortex street and form the vortex street in the far downstream. Regime II (1.5 < Ct < 10) : The inside Karman vortex street disappears. Regime III (15 < Ct ) : The Karman vortex street from the outside porous body is dominant. In this report, the characteristics of three wake structures are investigated in detail.