I note from the online HELP that "For the Navier-Stokes equations the HLLC Riemann solver (Toro et al. (1994)) is applied while for the shallow water equations the Roe's scheme (Roe (1981)) is applied."

Where can I make this selection, i.e., selecting Navier-Stokes equations?

I need to do this because "It is only possible to specify a contribution to the vertical momentum equation when the Navier-Stokes equations is used for calculating the flow" as otherwise it only allows for specifying the u and v velocity, and not the w velocity.

Thank you.