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Turbulent Flows

DNS for turbulent flow structure and improved RANS modelling

 

Wall jet

Turbulent wall jet structure

 Credit: Iffi Naqavi, James Tyacke and Paul Tucker

 

Jet in cross flow

 

Jet in cross-flow showing coherent structures

 Credit: Iffi Naqavi

 

Direct numerical simulation (DNS) is used to investigate flow and heat transfer. It provides detailed flow physics in the form of mean flow field, Reynolds stresses, turbulent kinetic energy and their budgets. It can also be used to fine-tune turbulence models.

 

Wall jet (top)

A fast moving stream issuing from a narrow slot along a wall in a quiescent medium forms a wall jet. The outer shear layer and near wall flow transition to turbulence. The wall turbulence interacts with the free shear layer turbulence.

Wall jets are used in gas turbine blade cooling, combustion chamber cooling, flow control on airfoils.

 

 Jet in cross flow (bottom)

The interaction of a jet with a cross stream flow results in a complex interaction, which determines the mixing and heat transfer near solid walls. At moderate Reynolds number (Re~6000) high resolution DNS reveals large scale flow structures responsible for flow mixing.

Jets in a cross flow are widely used in thin film cooling of gas turbine blades and combustion chambers.