8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 1/25
Shock/boundary layer interactions
Turbulent compressible channel ows
F.S. Godeferd
Laboratoire de M ecanique des Fluides et d’AcoustiqueEcole Centrale de Lyon, France
Journ ee Calcul Intensif en Rh one Alpes
1
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 2/25
Contents
• Presentation of the UFAST project
•
Numerical method• Shock in a curved channel
• Shock reection
• Perspectives
2
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 3/25
An example of normal shock/boundary layer interaction
[Experiment at the University of Cambridge - Bruce & Babinsky ]
3
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 4/25
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 5/25
The UFAST project — 2006-2009
Unsteady eFfects of shock
wAve induced SeparaTion European STREP project18 academic and industrialpartners
• Experiments
• RANS, URANS
• LES
• Control
http://www.ufast.gda.pl
4
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 6/25
Motivation of the study
unsteady shock wave boundary layer interaction
• Aeronautical industry shock waves on wings/proles, nozzle ows and inlet ows
• Interaction unsteadiness initiated and/or generated by SWBLI; often destabilized bythe outer ow eld; response of shock wave and separation to periodic excitations
• Control methods : synthetic jets, electro-hydrodynamic actuators, stream-wise vortex
generators and transpiration ow
Can we reproduce the unsteady interaction with URANS ? Need of costly LES ?
5
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 7/25
LMFA: URANS using platform elsA (ONERA)
Unsteady Reynolds-Averaged Navier-Stokes Simulations Physical model
• mean ow → Reynolds-averaged Navier-Stokes equations
• turbulence → two-equation model k -L (turbulent kinetic energy, mixing length); orone-equation model Spalart-Allmaras for turbulent viscosity ν t .
• Sutherland viscosity law ν (T ) = ν 0T 0 + C T + C
T T 0
3 / 2
• Adiabatic walls
6
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 8/25
Numerical method
• Conservative nite volume method
• Roe uxes with limiters
• Implicit Euler timestepping
• Multi-blocks structured mesh
•
Parallel resolution
7
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 9/25
Initialization - Example: Channel ow with bump [expe. in Queens U. Belfast]
Uniform initialization → Euler → laminar Navier-Stokes → turbulent Navier-Stokes
• Subsonic freestream: Ma = 0 .783• Peak: Ma = 1 .365•
Normal shock
Animation
8
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 10/25
Performance
Location Architecture # proc. # cores cpu/pt/ite Mem/pt Static max
seconds bytes speedup
LMFA Opteron 280 2Ghz 2 4 2 . 3 10 − 6 347 3.9
P2CHPD Opteron 252 2.6Ghz x3550 16 6 . 5 10 − 7 510 10 a
IDRIS Nec SX8 1 1 6 . 7 10 − 7 394 1´ECL
α
-Server EV7 1.15Ghz 1 19 . 9 10 − 6
495 1
9
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 11/25
URANS of curved channel ow at Ma = 1 .45Polish Institute of Mechanics experiment
Inlet conditions: P=101kPa; T=290K. Turbulence: Tu=1%; L=1% channel height.Outlet conditions: pressure ratio specied in URANS to match experimental shocklocation
10
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 12/25
Splitted geometry with N = 8 procs; 4.5 × 106 grid points
• Bottom wall boundary layer resolution: y+ 2• Side walls: y+ 20
Need to test the dependence of the solution on various elements of the simulation
11
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 13/25
Details of ow in shock zone
The simulation allows a detailed investigation of the owMach contours, showing Ma = 1 .45 upstream the shock
12
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 14/25
Oil ow visualization URANS streaklines
Detachment/re-attachment length
13
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 15/25
URANS streamlines → access to 3D ow structure
14
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 16/25
Adjustment of shock position: dependence on geometry
1 degree opening of channel at the outlet
Mach number contours in a transverse wall for choked and unchoked geometries. The
curve shows the Mach number at mid-section in this plane.
15
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 17/25
Dependence on expression of uxes and outlet pressure
Effect of counterpressure. Effect of uxes scheme: Roe or Jameson.
16
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 18/25
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 19/25
Shock reection case: expe. TU Delft
18
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 20/25
19
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 21/25
URANS
Turbulence model: k − L
Mach number at two times and uctuations at point in shock region
20
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 22/25
Unphysical solution! Huge detachment and unsteadiness due to poorly performingturbulence model.
Reason: turbulence is strongly damped in incoming boundary layer.
21
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 23/25
URANS
Turbulence model: Spalart-Allmaras
More reasonable shock detachment but steady ow
22
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 24/25
Perspective: introduce explicit uctuations at inlet
BL uctuations are sufcient to trigger SWBLI unsteadiness
Synthetic uctuations injection
23
8/3/2019 F.S. Godeferd- Shock/boundary layer interactions: Turbulent compressible channel flows
http://slidepdf.com/reader/full/fs-godeferd-shockboundary-layer-interactions-turbulent-compressible-channel 25/25
Perspectives of UFAST project
• Control of experimental ows
• Simulations with control
• Large eddy simulations and hybrid RANS/LES methods
• Comparison experiment/simulation results and synthesis, with industry partners
• Database available on web: 2009
24