Model Reduction in Discrete Vortex Methods for 2D Unsteady Aerodynamic Flows

Suresh Babu, A. V., Ramesh, K. and Gopalarathnam, A. (2016) Model Reduction in Discrete Vortex Methods for 2D Unsteady Aerodynamic Flows. In: 34th AIAA Applied Aerodynamics Conference, Washington, D.C., USA, 13-17 Jun 2016, (doi:10.2514/6.2016-4163)

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Abstract

In this paper, we propose a method for model reduction in discrete-vortex methods. Discrete vortex methods have been successfully employed to model separated and unsteady airfoil flows. Earlier research revealed that a parameter called the Leading Edge Suction Parameter (LESP) can be used to model leading-edge vortex (LEV) shedding in unsteady flows. The LESP is a measure of suction developed at the leading edge, and whenever the LESP exceeds a critical value, a discrete vortex is released from the leading edge so as to keep the LESP at the critical value. Though the method was successful in predicting the forces on and the flow field around an airfoil in unsteady vortex-dominated flows,it was necessary to track a large number of discrete vortices in order to obtain the solution. The current study focuses on obtaining a model with a reduced number of leading-edge vortices, thus improving the computation time. Vortex shedding from the leading edge is modelled by a shear layer that comprises of a few discrete vortices, and a single concentrated vortex whose strength varies with time. The single vortex at the end of the shear layer accounts for the concentrated vortical structure that comprises several discrete vortex elements in conventional vortex methods. A merging algorithm is initiated when the edge of the shear layer starts rolling up. Suitable discrete vortices are identified using a kinematic criterion, and are merged to the growing vortex at every time step. The reduced order method is seen to bring down the number of discrete vortices shed from the leading edge significantly.

Item Type:Conference Proceedings
Additional Information:The authors wish to gratefully acknowledge the support of the U.S. Air Force Office of Scientific Research through grant FA 9550-13-1-0179 and program managers Dr. Douglas Smith and Dr. Ivett Leyva.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ramesh, Dr Kiran
Authors: Suresh Babu, A. V., Ramesh, K., and Gopalarathnam, A.
Subjects:T Technology > TL Motor vehicles. Aeronautics. Astronautics
College/School:College of Science and Engineering > School of Engineering > Aerospace Sciences
Copyright Holders:Copyright © 2016 Arun Vishnu Suresh Babu, Kiran Ramesh, and Ashok Gopalarathnam
First Published:First published in 34th AIAA Applied Aerodynamics Conference 2016
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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