what does mean by diffusion?
 

Sometimes we are saying that, this scheme is more diffusive, lets say Upwind schme is more diffusive. or implicit beyond CFL> 1 is more diffusive. What does mean by that? Is it more numerical diffusion? Pls reply thanks everybody for taking interest.

Re: what does mean by diffusion?
 

>Is it more numerical diffusion?

Yes.

Re: what does mean by diffusion?
 

It mean that the physical profile such as density, pressure become broaden even though the discontinuity is too narrow.