Hi

I am trying to use two different time steps on different parts of the same grid (dense and coarse) to redurce the run time. I am using the adams bashforth time marching scheme to do it. It works fine but there are small errors introduced in the solution for a high frequence gust on an airfoil test case. does any body have any suggesstion about how to do this efficiently.

Thanks in advance

You need to be more specific about the schemes you use and how you match the two grid regions.The grid interfaces can give rise to parasite waves which might introduce oscillations in the solution,if not properly handled.