Question

Which of these assumptions are made for parabolizing Navier-Stokes equations?

(a) Viscous terms are neglected

(b) Viscous terms with derivatives in the stream-wise direction are neglected

(c) Derivatives in the stream-wise direction are neglected

(d) Viscous terms in the stream-wise direction are neglected

The question was posed to me in class test.

My question is based upon Mathematical Behaviour of PDE topic in portion Mathematical Behaviour of Partial Differential Equations of Computational Fluid Dynamics

Answer 1

Correct answer is (b) Viscous terms with derivatives in the stream-wise direction are neglected

The explanation: Parabolized Navier-Stokes equations can be used for supersonic flows over sharp-nosed cones. In this case, the flow field does not involve any reversed or separated flows. So, the derivatives of the viscous terms in the stream-wise direction are neglected and the equations are parabolized.