The velocity profile of a fully developed laminar flow in a straight circular pipe, as shown in the figure, is given by the expression. $$$u\left( r \right) = {{ - {R^2}} \over {4\mu }}\left( {{{dp} \over {dx}}} \right)\left( {1 - {{{r^2}} \over {{R^2}}}} \right)$$$
Where $${{dp} \over {dx}}$$ is a constant.

The average velocity of fluid in the pipe is

Water at $${25^0}C$$ is flowing through a $$1.0km$$ long $$G.I.$$ pipe of $$200mm$$ diameter at the rate of $$0.07$$ $${m^3}/s.$$ If value of Darcy friction factor for this pipe is $$0.02$$ and density of water is $$1000\,\,kg/{m^3}$$, the pumping power (in $$kW$$) required to maintain the flow is

Consider steady-state heat conduction across the thickness in a plane composite wall as shown in fig exposed to convection conditions on both sides.

Assuming negligible contact resistance between the wall surfaces, the interface temp $$T(C)$$ of the two walls will be

A coolant fluid at $${30^ \circ }C$$ flows over a heated flat plate maintained at a constant temperature of $${100^ \circ }C$$. The boundary layer temp distribution at a given location on the plate may be approximated as $$T=30+70exp(-y),$$ where $$y$$ (in $$m$$) is the distance normal to the plate and $$T$$ is in $$^ \circ C.$$ If thermal conductivity of the fluid is $$1.0W/mk,$$ the local convective heat transfer (in $$W/{m^2}K$$) at that location will be