管内移動球まわりの流れの数値解析

抄録

The flow around a sphere rising in a cylindrical pipe is numerically analyzed upon the axisymmetricity assumption. The sphere goes upward with constant velocity or with constant accerelation. The spherical coordinate mesh is attached to the sphere, however finite difference solution on the mesh is only auxiliary to a overset mesh method and does not affect on the cylindrical coorinate solution by HSMAC scheme. In the constant accerelation case whether the wall shear has its peak above or below the sphere depends upon whether the sphere velocity become larger than the background velocity or smaller than the latter. The qualitatively good agreement of sphere surface pressure is obtained with the existing experiment in the axisymmetric jet. Such assessment of the method predicts the applicability of the overset mesh method for calculation for the bubble or sedimendation of body in the pipe.