Exact Solutions of Navier Stokes

Question 1

In which types of flow does the nonlinear term vec{u}.gradvec{u} vanish?

Answer 1

Couette and Poiseuille flow

Question 2

Which types of flow, for which the nonlinear term vec{u}.gradvec{u} doesn’t vanish, can we find exact solution of Navier Stokes for?

Answer 2

Stagnation point flow, flow in convergent and divergent channels and flow over a porous wall.