Consider fully developed laminar flow of a very viscous fluid flowing through a tube of radius ro with uniform wall temperature, Ts. Far downstream, the energy equation reduces to a balance between radial conduction and
viscous dissipation, since the temperature no longer changes with
x. The energy equation becomes:
0=k.(1/r).d/dr(r dT/dr)+M.€ where €=(du/dr)^2
a) Solve for the temperature rise
T- Is
b) Determine the surface heat flux,
as" and the Nusselt number, N = hD/k
c) What do I - Ts and as reduce to with negligible viscous dissipation?