Irodov Problem 1.336

The Reynold's number for flow in a tube within a circular tube is given by . Here Q is the volumetric flow rate i.e. volume of fluid flowing per sec. Hence, for this problem with pipe of reducing cross section it is given by . Since Q does not change along the tube for two points separated by a distance the ratios of the Reynold's number will be . The Reynold.s number will increase as the tube narrows.