Inviscid Flow - Reynolds Number

Reynolds Number

The assumption of inviscid flow is generally valid where viscous forces are small in comparison to inertial forces. Such flow situations can be identified as flows with a Reynolds number much greater than one. The assumption that viscous forces are negligible can be used to simplify the Navier-Stokes solution to the Euler equations.

The Euler equation governing inviscid flow is:

which is admittedly the Newton's second law applied on a flowing infinitesimal volume element. In the steady-state case, combined with the continuity equation of mass, can be solved using potential flow theory.