Global stability analysis of a boundary layer with surface indentations

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Title: Global stability analysis of a boundary layer with surface indentations
Authors: Appel, T
Mughal, MS
Ashworth, R
Item Type: Conference Paper
Abstract: In the quest for laminar flow control on aircraft wings, quantifying the impact of structural deformation on laminar-turbulent transition remains a challenge. The purpose of this work is to numerically investigate the stability of two-dimensional incompressible boundary layers developing on a flat-plate geometry with indented surfaces of different depths. These surface indentations generate laminar separation bubbles, known to have strong destabilizing effects on Tollmien-Schlichting disturbances. The parallel efficiency of the developed computational tool based on state-of-the-art numerical libraries allows rapid parametric studies within the usually expensive global stability analysis framework. Using an incompressible linearized Navier-Stokes formulation, we use the perfectly matched layer method to absorb waves at the inflow and outflow boundaries. Forced receptivity analysis is performed in order to investigate the effect of the indentation region on the convecting Tollmien-Schlichting waves. Furthermore, the likelihood of global temporal mechanisms arising is investigated through BiGlobal stability analysis. The deepest surface indentation, which features a peak-reversed flow velocity of 9 % in the laminar separation bubble, leads to significant levels of Tollmien-Schlichting amplification. It is also characterized by two temporally unstable modes, namely a dominant, localized stationary mode as well as a traveling Kelvin-Helmholtz mode.
Issue Date: 17-Jun-2019
Date of Acceptance: 15-Jun-2019
Publisher: American Institute of Aeronautics and Astronautics
Journal / Book Title: AIAA Aviation 2019 Forum
Copyright Statement: © 2019 by Airbus Operations Ltd. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.
Sponsor/Funder: Innovate UK
Commission of the European Communities
Funder's Grant Number: 113022
Conference Name: AIAA Aviation 2019 Forum
Publication Status: Published
Start Date: 2019-06-17
Finish Date: 2019-06-21
Conference Place: Dallas, Texas
Online Publication Date: 2019-06-15
Appears in Collections:Mathematics
Applied Mathematics and Mathematical Physics
Faculty of Natural Sciences

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