solid_rotation

# Define solid rotation velocity field:
tau      = 100*secinmyr        # 100-Myr convection overturn period in seconds
v0       = 2*np.pi/tau         # angular velocity (in rad/sec)
xh       = xx-0.5*h            # x-distances to hor middle of mesh (on xx mesh)
zh       = zz-0.5*h            # z-distances to vert middle of mesh (on xx mesh)
vx       = -v0*zh              # define solid rotation velocity field: v=vo*r:
vz       = v0*xh