Time Step Problem in NS equations code
 

Hi everyone,

This is my first post in this site.
I am trying to simulate compressible(supersonic) flow laminar boundary layer on a flat plate as given in CFD JD Anderson last chapter problem except that i am solving through Finite Volume Method rather than FDM used in the book.
I am using Van Leer Flux Splitting for Inviscid flux discretisation,
Central differencing for gradient calculation and euler explicit scheme for time integration.I have considered isothermal wall on the bottom.

1. Now the problem is I am using dimensional equations and Re no. is found out to be more than 10^7. But it should be less than 5*10^5 for laminar flow on flat plate. I am able to generate a boundary layer though. Help me with this!!!!
2. Time step dt is found to be zero in every iteration and i am able to generate boundary layer. How is this even possible. Even if i increase the accuracy of time step it's still showing zero. CFL no. used is 0.2 and I have used Sutherland's law for updating viscosity. Pls help how to overcome this problem.

Thank You.