Recovering pressure from the velocity field is easy. The discrete weak equation for the pressure gradient is, ( g i , ∇ ∇ p ) = − − ( g i , ( u ⋅ ⋅ ∇ ∇ ) u j ) − − ν ν ( ∇ ∇ g i : ∇ ∇ u j ) + ( g i , f I )