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|Title:||CFD models of transitional flows|
|Authors:||Di Pasquale, Davide|
|Presented at:||University of Leicester|
|Abstract:||In favour of the more widely investigated laminar and turbulent regimes, the study of the transitional flow regime has received a lower research effort. The important effect of laminar-turbulent transition is not included in the majority of today’s engineering CFD simulations. This thesis deals with the problem of modelling a low Reynolds number zero pressure gradient boundary layers in an incompressible flow without any heat-transfer effects. The zero-pressure gradient transitional boundary layer is one of the canonical shear flows important in many applications and of large theoretical interest. An overview of the more widely used approaches to model transition in Computational Fluid Dynamics (CFD), has shown the challenge of modelling transition by CFD. The approaches are compared to one another, highlighting their respective advantages and drawbacks. This work then progress to document some of the precautions that are required to interpret and use the European Research Community on Flow, Turbulence and Combustion (ERCOFTAC) dataset to calibrate CFD codes. Finally, this work implements and tests the transition model of Suzen and Huang and the laminar kinetic energy transition method by Walter and Leylek in the in-house computational fluid dynamics scheme Cosmic. Cosmic is a finite-volume in-house CFD code written in FORTRAN90. It is a multi-block Navier-Stokes solver, which uses MPI(Message Passing Interface) and is capable of handling complex geometries. The test cases are simple flat plate experiments. The test cases are used to test the predicting capabilities of two different transitions model, under various stream turbulence intensity, Reynolds number variations. After having investigated both models it is possible to state that the laminar kinetic energy method is more reliable with respect to the intermittency transport method when the flow-field is subjected to a lower free-stream turbulence intensity case, but both models have shown similar behaviour in case of higher free-stream turbulence intensity.|
|Rights:||Copyright © the author. All rights reserved.|
|Appears in Collections:||Theses, Dept. of Engineering|
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