A dimensionless group called the Reynolds number is defined for flow in a pipe or tube where V is the average velocity in the pipe, is the fluid density,  is the fluid viscosity, D is the tube...

A dimensionless group called the Reynolds number is defined for flow in a pipe or tube

where V is the average velocity in the pipe, is the fluid density,  is the fluid viscosity, D is the tube diameter. The second form of the group indicates that it is a ratio of the convective (turbulent) momentum flux to the molecular (viscous) momentum flux, or the ratio of inertial forces (which are destabilizing) to viscous forces (which are stabilizing). When viscous forces dominate over inertial forces, the flow is laminar and fluid elements flow in smooth, straight streamlines, whereas when inertial forces dominate, the flow is unstable and the flow pattern break up into random fluctuating eddies. It is found that laminar flow in a pipe occurs as long as the value of the Reynolds number is less than 2000. Calculate the maximum velocity and the corresponding flow rate (in cm3 /s) at which laminar flow of water is possible in tubes with the following diameters:

D =0:25; 0:5; 1:0; 2:0; 4:0; 6:0; 10:0 in: