In fully developed laminar flow in the circular pipe, the head loss due to friction is directly proportional to ....... (Mean velocity/square of the mean velocity)

A fluid is said to be Newtonian fluid when the shear stress is

The velocity components in the $$x$$ and $$y$$ directions are given by $$u = \lambda x{y^3} - {x^2}y,$$ $$v = x{y^2} - {3 \over 4}{y^4}.$$ The value of $$\lambda $$ for a possible flow field involving an incompressible fluid is

A counter flow heat exchanger is to heat air entering at $${400^ \circ }C$$ with a flow rate of $$6$$ $$kg/s$$ by the exhaust gas entering at $${800^ \circ }C$$ with a flow rate of $$4$$ $$kg/s$$. The overall heat transfer coefficient is $${100^ \circ }C$$ $$W/\left( {{m^2}K} \right)$$ and the outlet temperature of the air is $${551.5^ \circ }C.$$ Specific heat at constant pressure for both air and the exhaust gas can be taken as $$1100$$ $$J/(kgK).$$ Calculate the heat transfer area needed and the number of transfer units.