Question

Tutorial 4 turbulence modelling Define the time averaged velocity component as used in turbulent flows 1. 2. Define the term turbulence intensity 3. Apply time averaging to the Boundary Layer equation and comment or the new term(s) and what they represent. Given a flow with a turbulence intensity of 0.5%, a length scale of 0.0125m and a flow speed of 120m/s - calculate k and epsilon for the inlet boundary assuming C(mu) -0.09 List in order of accuracy and describe the differences between, LES DES, potential flow, RANS, and DNS. 5.

Answer 1

"Turbulence intensity: It is defined as the Turbulence intensity is a scale characterizing turbulence expressed as a percent An idealized flow of air with absolutely no functions flow of air with absolutely no fluctuations in air speed (or) direction would have a ""Turbulence intensity Value of 0% Turbulence intensity, also often referred to as turbulence level is defined as I = u prime/v prime where u prime is the root-mean-square of the turbulent velocity fluctuations v prime = mean velocity (Reynold's averaged) Time averaged velocity component as used in turbulent flow? A time - averaged method to obtain quantitative measurements in turbulent flow by phase flow encoding NMR imaging is introduced with this method time averaged velocity profiles and turbulence intensities can be determined. Time - averaged velocity profile for pipe flow of water driven by a constant pressure gradient at Reynolds number from 1200 to 9400 were visualized. A precise correlation "