Flow through Curved Pipes

If the pipe is not straight, the velocity distribution over the section is altered and the direction of flow of fluid is continuously changing. The frictional losses are therefore somewhat greater than for a straight pipe of the same length. If the radius of the pipe divided by the radius of the bend is less than about 0.002 however, the effects of the curvature are negligible.

It has been found that stable streamline flow persists at higher values of the Reynolds number in coiled pipes. Thus for instance, when the ratio of the diameter of the pipe to the diameter of the coil is 1 to 15, the transition occurs at a Reynolds number of about 8000.