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Effect of humps and indentations on boundary-layer transition of compressible flows using the AHLNS methodology

Franco, Juan and Hein, Stefan and Valero, Eusebio (2018) Effect of humps and indentations on boundary-layer transition of compressible flows using the AHLNS methodology. In: 7th European Conference on Computational Fluid Dynamics (ECFD 7). 7th European Conference on Computational Fluid Dynamics (ECFD 7), 11-15 June 2018, Glasgow, UK.

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Official URL: http://www.eccm-ecfd2018.org/admin/files/fileabstract/a1821.pdf

Abstract

The presence of surface irregularities like humps or indentations can cause regions of localized strong streamwise gradients in the basic flow quantities. These large gradients can significantly modify the linear mechanisms that lead to laminar-turbulent transition in wall-bounded flows (e.g. Tollmien-Schlichting waves). Standard methodolo- gies like LST (Local Stability Theory) or PSE (Parabolized Stability Equations) can be applied in regions far from the surface irregularities where the streamwise variations are small. However, their formulations are not suited for handling the presence of such large streamwise gradients. The Adaptive Harmonic Linearized Navier-Stokes (AHLNS) equations can handle these large streamwise gradients by using a fully-elliptic system of equations as in DNS (Direct Numerical Simulation). Moreover, as in PSE a wave-like character of the instabilities is assumed, leading to a significant reduction in the number of streamwise grid points required compared with DNS computations. In the present study, smooth humps/indentations with height/depth comparable with the local boundary-layer displacement thickness are investigated. The effect of the hump/indentation on the spatial evolution of convective instabilities, in terms of N-factors, is presented. It is shown that the shape of the surface irregularity plays an important role in the growth of convective instabilities.

Item URL in elib:https://elib.dlr.de/123888/
Document Type:Conference or Workshop Item (Speech)
Title:Effect of humps and indentations on boundary-layer transition of compressible flows using the AHLNS methodology
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Franco, JuanJuan.Franco (at) dlr.deUNSPECIFIED
Hein, Stefanstefan.hein (at) dlr.deUNSPECIFIED
Valero, EusebioUniversidad Politécnica de MadridUNSPECIFIED
Date:June 2018
Journal or Publication Title:7th European Conference on Computational Fluid Dynamics (ECFD 7)
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Laminar-Turbulent Transition, Surface Irregularities, Stability, AHLNS
Event Title:7th European Conference on Computational Fluid Dynamics (ECFD 7)
Event Location:Glasgow, UK
Event Type:international Conference
Event Dates:11-15 June 2018
Organizer:ECCOMAS
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > High Speed Configurations, GO
Deposited By: Franco, Juan
Deposited On:29 Nov 2018 10:07
Last Modified:23 Feb 2019 11:51

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