I want to model the contact between rough surfaces, and capture the interface contact length accurately to model electrical contact resistance. I've been reading different approaches for doing similar multiscale modeling, but different papers have used different approaches (RVE, UEL etc.) to construct a small-scale model that includes the rough asperities and pass the values to a larger-scale model for computational efficiency. 

I'm not exactly sure which of the 2 would be more suitable for this purpose. Posting here in the rare case that someone has some prior experience with multiscale modeling.