A NEW APPROACH TO THE CALCULATION OF THE VARIATION OF THE MIXING LENGTH OVER THE PIPE DIAMETER

Abstract

Despite the approximate nature of the Prandtl concept of the mixing length, it remains one of the most easy and useful method in the prediction of the velocity distribution. It had been successfully used in the prediction of the velocity distribution in many practical problems (i. e. in pneumatic conveying). Since Prandtl's assumption on the mixing length L/r=0,14--0,08(1-y/r)² -0,06(1-y/r)⁴ is not suitable for Re number lower than 10⁵, a new approach is developed, which is also valid for Re lower than 10⁵, for both smooth and rough pipes.