Computation of inviscid flows: Various approximations

The Navier-Stokes equations describe the fluid motion in its utmost generality: the flow could be transient, three dimensional, rotational, and turbulent. In practice it is not possible to solve this system of equations corresponding to any given flow situation especially when the geometry is complex (for example the flow past a cylinder, sphere, or an airfoil of an aircraft). Because of tremendous growth in computing resources in recent years, it has been possible to try direct simulation of Navier-Stokes equations for a very simple geometry or try Reynolds averaged Navier-Stokes equations for a geometry of medium complexity. However, certain aspects of flow fields can be examined by simplifying the governing equations. These simplifying assumptions idealize the flow and are described in sequence. (Derived from text