Richardson Extrapolation to check time and space convergence
 

Hi,

I have been given a problem and to check the convergence I have been told that to check the time and space convergence I need to use a standard Richardson extrapolation method so that I don't have to refine the mesh or use smaller time steps.

I did a bit of research and from what I found to use Richardson extrapolation you need to know the step sizes (either the mesh size or the time steps) ..So I am a bit confused on how I can test the convergence of my problem using this method and without refining the mesh or reducing the time step.... Any hints would be very much appreciated.

Thanks a lot in advance!