The inlet effect on the drag factor of a sphere in a tube (Q1073667)

The creeping motion around a sphere situated axisymmetrically near the entrance of a semi-infinite circular cylindrical tube is analyzed using infinite series solutions for the velocity components, pressure and the stream function. Truncating the infinite series, the corresponding coefficients in the series are determined by a collocation technique. The drag factor and the stress distribution on the surface of the sphere are calculated for the sphere in motion in quiescent fluid and for the flow with uniform velocity at the entrance past a rigidly held sphere. The results indicate that a sphere near the entrance which has a uniform entrance velocity profile will suffer larger drag than that in an infinite tube. The convergence of the collocation technique is tested by numerical calculation. It is shown that the technique has good convergence properties.