The impulsively started flow over oblate spheroids

The problem of the impulsively started flow over an oblate spheroid is solved using the series truncation method in which the stream function and vorticity are expanded in terms of series of Legendre functions. The resulting time-dependent differential equations are solved using the Crank-Nicolson finite difference scheme. The parameters involved are the Reynolds number and the axis ratio. The range of Reynolds numbers considered is from 5 to 100 while the axis ratio is considered at values of A_r = 0.6 and 0.76. The time variation of the flow field is presented in the form of streamline and equi-vorticily patterns as well as pressure and surface vorticity distributions. The time development of the separation angle, wake length, and the frictional and total drag coefficients are also presented. The large time (steady) values of the drag coefficient for the special case of a sphere are compared with previously known data and the agreement is satisfactory.