Guilin Sun
Ansys Employee

As long as you can get the result you want, this method should work.

As you know, this method uses the fundamental definition to get the group velocity. and the time monitor should be located where there is only one mode, since the group velocity is associated with a single mode. Otherwise it may lose its physical meaning. You can use mode expansion monitor, or port to decopose the modes at that location and see if there are other modes there.

Since it is from the fundamental definition, you will need to know if anything violates the assumption for the definition. You may need to simulate longer, use the proper last section of the time signal.