# 8th European PostgraduateFluid Dynamics Conference

## 6th – 9th July 2016Warsaw, Poland

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# Quasi-laminar theory for relaminarization in a highly accelerated high-Re turbulent boundary layer

Rajesh Ranjan1, S M Deshpande1, Roddam Narasimha1
1Jawaharlal Nehru Centre for Advanced Scientific Research
The phenomenon of relaminarization is observed in many flow situations, including an initially turbulent boundary layer subjected to strong favourable pressure gradient (FPG). Available turbulence models have hitherto been unsuccessful in correctly predicting the boundary layer parameters for such flows. Narasimha Sreenivasan (1973) proposed quasi-laminar theory (QLT) based on a two-layer model to explain the later stages of relaminarization.

Recent work by Bourassa Thomas (2009) reports a detailed study of relaminarizing flow, where all the flow quantities of interest are measured at relatively high Reynolds number ($Re_{\theta }$ = 4600 upstream of FPG) and high FPG (acceleration parameter $K$=4.5 $\times 10^{-6}$).In the present work, the equations of QLT for both the layers were solved exactly for the this flow. In the later stages of relaminarization, QLT provides a much superior match with the experimental results than the results with a turbulent boundary layer
Keywords: Turbulence, Applied fluid dynamics, Computational methods