fluid is flowing upward through a 1cm diameter pipe at 0.15m/s find the necessary power per unit length to drive the flow through the pipe.
flux of momentum out - flux of momentum in= forces acting on the CV (tau( downward) and F_y( upward))
force x velocity = power.
The Attempt at a Solution
I found all the forces acting on the CV:
and F subscript y
I ignored the weight as it might already be contained in the Force y which pushes the flow upward and also because I have no idea what the mass of the water would be here.
in this case mom in= mom out => tau( shear stress)*A=F_y
tau= 0.03006 Pa
=> F_y*U( velocity)=1.17809*10^-5 J/S