- Modified the DG advection term so we can now integrate by parts twice when performing multi-phase simulations. - Removed an unnecessary multiplication by u_nl_div_q.
- Modified the DG advection term so we can now integrate by parts twice when performing multi-phase simulations.
- Removed an unnecessary multiplication by u_nl_div_q.

FluidityProject/multifluids,FluidityProject/multifluids,FluidityProject/multifluids,FluidityProject/multifluids