Transport Phenomena

4. (20 pts) Show that the normal component of the viscous stress Tnn on a solid surface is identical zero. For this, it is sufficient to prove it for a planar surface. Thus, define a solid surface perpendicular to the z-axis and show that Tax = 0 Note that this is a physically important boundary condition for the normal viscous stress on a solid surface. To see the general formulation of this problem (valid for any coordinate system), please read Problem 6-4 Deen (which you do not need to solve)