Ph.D Research
PhD Research
Title
An Investigation into Methods to aid the Simulation of Turbulent Separation Control
Abstract
The reduction of drag on commercial aircraft is an active field of
study especially with environmental pressures to reduce the carbon
emissions associated with climate change. To this end, the
AEROMEMS-II project was commissioned by the EU with a view to
investigate methods for reducing drag by using MEMS devices for
controlling separation. One method for investigating flow control
devices is to use the field of Computational Fluid Dynamics (CFD) to
simulate the flow interactions produced in flow control applications
and assess their effect.
Simulating such flows can be computationally expensive so a number
of methods have been investigated here to assess their use in flow
control simulation applications. The first of these is the Immersed
Boundary Method (IBM) which allows complex geometries to be
simulated using simple cartesian grid CFD codes. IBMs are found to
reduce requirements whilst maintaining flow resolution and
accuracy.
Next is the use of turbulence modelling with wall functions to
reduce the need for fine grids near any solid surfaces. This method
is found to work well and can allow the grid spacing near the wall
to be 100 times coarser than with no wall functions applied.
Finally, Detached Eddy Simulation (DES) has been considered as a
method for allowing unsteady flow control structures to be simulated
without being damped by conventional turbulence modelling. Each of
these methods is presented, implemented and validated against known
flow cases to assess their abilities fully.
All three methods have then been applied together to a known
experimental turbulent flow-control set-up at the University of
Lille (fellow partners in the AEROMEMS-II project) in order to
assess the feasibility of using all of these methods together to
simulate flow control. All three of these methods are seen to work
well together although not always with the same effect.
References
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- Spalart, P., Jou, W., Strelets, M. & Allmaras, S. (1997) "Comments on the feasibility of LES for wings & on a hybrid RANS/LES approach" First AFOSR International conference on DNS/LES
- Bernard, A., Foucaut, J.M., Dupont, P. and Stanislas, M. (2003) "Decelerating Boundary Layer: A new scaling and mixing length model" AIAA Journal 41(2): 248-255