Question

In a closed pipe of radius R, fluid (having some viscosity) is flowing laminarly. Which point along a cross section will have maximum speed?

(a) Centre

(b) Near the wall of pipe

(c) R/2 from centre

(d) All points will have same speed

Answer 1

The correct option is (a) Centre

The best explanation: We know that the shear strain rate is v/l, where v is velocity of layer and l is distance of that layer from layer having zero speed                                                                                                                               Here, the layer in contact with pipe wall will have zero speed.                                                                        Therefore, the velocity will increase as one goes away from the wall and will be maximum at centre.