Rotational flows in electrically conducting and non-conducting fluids

Concerning rotational flows, the validity of a boundary condition used in the numerical computation of viscous flow problems is examined and the behavior of a swirling flow through tubes of varying radius is studied, treating the fluid as inviscid. In a fluid region weakly affected by the body force, a slip wall can be used to approximate a realistic no-slip solid surface if the Reynolds number is reasonably large. In a region where the body force has a strong effect, a no-slip wall may never be replaced by a slip wall even if the Reynolds number is extremely high. The problem of swirling flow through tubes with abrupt contraction or expansion is solved using the method of matching up- and down-stream solutions. There is no restriction on the rotational speed of the flow in this analytical method. In all solved cases, the secondary flows and wave patterns are displayed at various Rossby numbers.