Pipe diameter and reynolds number. an oil is being pumped inside a 10.0-mm-diameter pipe at a reynolds number of 2100. the oil density is 855 kg/m3 and the viscosity is 2.1 × 10−2 pa · s. what is the velocity in the pipe? it is desired to maintain the same reynolds number of 2100 and the same velocity as in part (a) using a second fluid with a density of 925 kg/m3 and a viscosity of 1.5 × 10−2 pa · s. what pipe diameter should be used?