Master of Engineering Science
Mechanical and Materials Engineering
The present numerical work is an attempt towards modelling of freely decaying homogeneous isotropic turbulence with its application in experimental modelling of the effect of incident turbulence on flow around 2D and 3D bluff-bodies. Both steady, Reynolds Averaged Navier Stokes (RANS) and unsteady, Large Eddy Simulation (LES), 3-D numerical computational fluid dynamics (CFD) techniques have been employed to characterise the inviscid decay of large-scale turbulence in terms of the characteristic r.m.s turbulent velocity fluctuations ( ) and the local integral length scale (Lu). The large-scale turbulent properties extracted from the current numerical simulations are inter-related and are shown to behave predominantly as Saffman turbulence, which states Lu3 ≈ constant. The other focus from the current study was on modelling inlet conditions for bluff-bodies in a freestream flow. A set of three-correlation equations are formulated based on the large-scale turbulent properties that are effective in estimating the initial and local freestream turbulence conditions. The set of prediction equations can be deemed useful for researchers developing wind-tunnel models in the presence of freestream turbulence. Additionally, the set of equations is also reliable in determining appropriate near-constant turbulent conditions based on the upstream inlet conditions. The current study aims at designing the region of constant turbulent properties of a desired magnitude that can be helpful for boundary layer and heat transfer studies over a bluff-body.
Sarkar, Dwaipayan, "A numerical tool for predicting the spatial decay of freestream turbulence." (2018). Electronic Thesis and Dissertation Repository. 5331.