[firedrake] how to set up random initial conditions?

Hello, I was thinking of taking my Quasi-Geostrophic demo that I recently submitted and change the initial conditions to be a random field. Then we can see the evolution of freely evolving 2D turbulence. Unfortunately, I am not sure how to pick random initial conditions in firedrake. I found issue 514 that suggested doing the following: import numpy as np perm_array = np.random.randn(Nx, Ny, Nz) I guess this works if you have a regular mesh. But if I have an irregular mesh then is there a way to define this for the mesh? Cheers, Francis