Large Eddy Simulation Of A Transition Process In
Separated-reattached Flows
Author(s)
Z. Yang
Abstract
Transition from laminar to turbulence in separated-reattached flow occurs
frequently and plays a very important role in engineering. Hence, accurately
predicting transition is crucial since the transition location has a significant
impact on aerodynamics performance and a thorough understanding of the
transition process can greatly help to control it, e.g. to delay the turbulent phase
where laminar flow characteristics are desirable (low friction drag) or to
accelerate it where high mixing of turbulent flow are of interest (in a combustor).
However, it is very difficult to predict transition using conventional Reynolds-
Averaged-Navier-Stokes (RANS) approach and the transition process is not fully
understood. Nevertheless significant progress has been made with the simulation
tools such as Large Eddy Simulation (LES) which has shown improved
predictive capabilities over RANS and can predict transition process accurately.
This paper presents briefly LES formalism and followed by its applications to
predict/understand the transition process and unsteady behaviour of the free
shear layer in separated-reattached flow.
Keywords: transition, separated-reattached flow, LES, RANS, shear layer,
unsteady, turbulence.
1 Introduction
Separated flows are common and play an important role in many engineering
applications from cooling of small electronic devices to airfoil and turbomachinery
design. If a separated flow reattaches downstream a separation bubble
is formed and its characteristics are a crucial aspect of the engineering design
process. Three types of separation bubble are possible depending on the state of
Keywords
transition, separated-reattached flow, LES, RANS, shear layer,
unsteady, turbulence
Related Book
Other papers in this volume
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