Abstract: | A higher-order compact scheme on the nine point 2-D stencil is developed
for the steady stream-function vorticity form of the incompressible Navier-Stokes (NS) equations in spherical polar coordinates, which was used earlier only for the cartesian and cylindrical geometries. The steady, incompressible, viscous and axially symmetric flow past a sphere is used as a model problem. The non-linearity in the N-S
equations is handled in a comprehensive manner avoiding complications in calculations. The scheme is combined with the multigrid method to enhance the convergence
rate. The solutions are obtained over a non-uniform grid generated using the transformation r = eξ while maintaining a uniform grid in the computational plane. The
superiority of the higher order compact scheme is clearly illustrated in comparison
with upwind scheme and defect correction technique at high Reynolds numbers by
taking a large domain. This is a pioneering effort, because for the first time, the fourth
order accurate solutions for the problem of viscous flow past a sphere are presented
here. The drag coefficient and surface pressures are calculated and compared with
available experimental and theoretical results. It is observed that these values simulated over coarser grids using the present scheme are more accurate when compared to
other conventional schemes. It has also been observed that the flow separation initially
occurred at Re=21. |