Development and Verification of CFD Program by Central Difference Calculus for Incompressible Fluid

(Effects of Unsteady Reynolds Stress)

Abstract

A method for predicting the coefficient of friction of pipes with smooth walls in turbulent flow was investigated without using the knowledge from experiments. As a result, the following was found. (1) It was necessary to secure a sufficient amount of turbulence that naturally occurred from the wall surface. For a shape such as a square cross section in which no unevenness existed on the wall surface of the calculation model, it was effective to rotate around the central axis to increase unevenness on the wall of the calculation model and to occur turbulence. (2) A method to control the strength of the turbulence was clarified. The coefficient of friction of pipes with smooth walls could be calculated by controlling the strength of the turbulence to minimize the pressure loss.