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Effect of Mach number on the structure of turbulent spots

Effect of Mach number on the structure of turbulent spots
Effect of Mach number on the structure of turbulent spots
Direct numerical simulations have been performed to study the dynamics of isolated turbulent spots in compressible isothermal-wall boundary layers. Results of a bypass transition scenario at Mach 2, 4 and 6 are presented. At all Mach numbers the evolved spots have a leading-edge overhang, followed by a turbulent core and a calmed region at the rear interface. The spots have an upstream-pointing arrowhead shape when visualized by near-wall slices, but a downstream-pointing arrowhead in slices away front the wall. The lateral spreading of the spot decreases substantially with the Mach number, consistent with a growth mechanism based on the instability of lateral shear layers. Evidence for a supersonic (Mach) mode substructure is found in the Mach 6 case, where coherent spanwise structures are observed under the spot overhang region.
boundary-layer-flow, simulation, transition, laminar
0022-1120
225-234
Krishnan, L.
4eb5cfc3-d3e2-474d-a63b-e1f80de54bf6
Sandham, N.D.
0024d8cd-c788-4811-a470-57934fbdcf97
Krishnan, L.
4eb5cfc3-d3e2-474d-a63b-e1f80de54bf6
Sandham, N.D.
0024d8cd-c788-4811-a470-57934fbdcf97

Krishnan, L. and Sandham, N.D. (2006) Effect of Mach number on the structure of turbulent spots. Journal of Fluid Mechanics, 566, 225-234. (doi:10.1017/S0022112006002412).

Record type: Article

Abstract

Direct numerical simulations have been performed to study the dynamics of isolated turbulent spots in compressible isothermal-wall boundary layers. Results of a bypass transition scenario at Mach 2, 4 and 6 are presented. At all Mach numbers the evolved spots have a leading-edge overhang, followed by a turbulent core and a calmed region at the rear interface. The spots have an upstream-pointing arrowhead shape when visualized by near-wall slices, but a downstream-pointing arrowhead in slices away front the wall. The lateral spreading of the spot decreases substantially with the Mach number, consistent with a growth mechanism based on the instability of lateral shear layers. Evidence for a supersonic (Mach) mode substructure is found in the Mach 6 case, where coherent spanwise structures are observed under the spot overhang region.

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More information

Published date: 2006
Keywords: boundary-layer-flow, simulation, transition, laminar
Organisations: Aerodynamics & Flight Mechanics

Identifiers

Local EPrints ID: 43016
URI: http://eprints.soton.ac.uk/id/eprint/43016
ISSN: 0022-1120
PURE UUID: a4b8cd7c-118a-4d1c-a325-490f94ddfeff
ORCID for N.D. Sandham: ORCID iD orcid.org/0000-0002-5107-0944

Catalogue record

Date deposited: 08 Jan 2007
Last modified: 16 Mar 2024 03:03

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Contributors

Author: L. Krishnan
Author: N.D. Sandham ORCID iD

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