Hi,
I have built a 2D model of a SAW delay line device in the time domain, where I set up a voltage pulse on one set of IDTs, which creates a surface wave that travels across the surface and is detected by the other set of IDTs. This works and gives me the results that I expect with my set up. I designed this for a frequency of 20MHz and had placed the IDTs reasonable close together. When looking at the potential plot over time, I can see the surface wave travelling across the surface.
I then took the same model (copied it) and adjust it for a different frequency, 5MHz which alters the dimensions. I built the model in a way where the dimensions of the domains were dependant on the frequency so they adjusted automatically with one change. Additionally, I change one of the dimension to have a greater distance between the IDTs.
This updated model now reponds differently, instead of a surface wave moving across the boundary of the domain, I now have bulk wave that travels through the bulk of the domain and then reflects causing a different response at my output IDTs.
Currently I'm thinking perhaps it could be due to the meshing, as I think I am using the same mesh parameters for the both, and for a 5 MHz design this is probably finer than needed. Resulting in a greater simulation time.