Symmetrically oscillating viscous flow over an elliptic cylinder

The paper deals with the problem of two-dimensional oscillating viscous flow past an elliptic cylinder. The flow is considered incompressible and two-dimensional, and the free-stream oscillations are harmonic. These oscillations are only allowed in the magnitude of the free-stream velocity, which is always parallel to one of the elliptic section axes. The resulting flow field is symmetrical about either the major or minor axis of the ellipse. The parameters involved are the cylinder axis ratio, Reynolds number and the oscillation frequency. The major-minor axis ratio of the elliptic cylinder ranges between 0·5 and 0·8, the Reynolds number ranges between 500 and 10³, and the frequency parameter ranges between π/4 and π/2. Present calculations are performed within the range of sufficiently large oscillation amplitude to induce separation. The time variation of the flow field is presented in the form of streamline patterns as well as the surface pressure distribution. The time variation of the drag coefficients is also presented and compared with the inviscid flow solution. The results show that the force coefficient predicted for the case of viscous flow approaches that of potential flow as the Reynolds number and frequency increase.