Active control of compressible supersonic wall-bounded flow using direct numerical simulations with spanwise velocity modulation at the walls using PyFR - presented by Prof. Dr. Holger Foysi

Active control of compressible supersonic wall-bounded flow using direct numerical simulations with spanwise velocity modulation at the walls using PyFR

Prof. Dr. Holger Foysi

HF
Slide at 02:17
STABILIZING EFFECT OF COMPRESSIBILITY? Reduced turbulent shear layer growth rate with increasing convective Mach number (e.g. Bradshaw '77) stabilisation of the flow in the supersonic regime (Sarkar '95) Decreased turbulent production, associated with decrease in pressure fluctuations and pressure-strain terms (Vreman '97, Sarkar et al. '96, Freund et al. 2000, Pantano et al. 2002) In supersonic channel flow increased anisotropy regarding turbulent stresses is observed (Huang et al (1995), Foysi et al. (2004)) One reason is the strong decrease in the pressure-strain correlation Non-locality of pressure fluctuations - pressure gradient at each point determined by momentum transfer of larger surrounding "vortex" influencing it. (determined by two-point correlation) Point sees effective density, smaller than local density - Green's function analysis. Smoothing of gradients in high Mat isotropic turbulence (Foysi (2005)) UNIVERSITÄT SIEGEN Holger Foysi
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References
  • 1.
    P. Bradshaw (1977) Compressible Turbulent Shear Layers. Annual Review of Fluid Mechanics
  • 2.
    S. Sarkar (1995) The stabilizing effect of compressibility in turbulent shear flow. Journal of Fluid Mechanics
  • 3.
    B. E. R. T. VREMAN et al. (1997) Large-eddy simulation of the turbulent mixing layer. Journal of Fluid Mechanics
  • 4.
    S. Sarkar (1997) On Density and Pressure Fluctuations in Uniformly Sheared Compressible Flow. Fluid Mechanics and Its Applications
  • 5.
    J. B. FREUND et al. (2000) Compressibility effects in a turbulent annular mixing layer. Part 1. Turbulence and growth rate. Journal of Fluid Mechanics
  • 6.
    C. PANTANO and S. SARKAR (2002) A study of compressibility effects in the high-speed turbulent shear layer using direct simulation. Journal of Fluid Mechanics
  • 7.
    P. G. Huang et al. (1995) Compressible turbulent channel flows: DNS results and modelling. Journal of Fluid Mechanics
  • 8.
    H. FOYSI et al. (2004) Compressibility effects and turbulence scalings in supersonic channel flow. Journal of Fluid Mechanics
  • 9.
    H. Foysi et al. (2005) ON THE MICRO-STRUCTURE OF THE SCALAR FIELD IN COMPRESSIBLE FORCED ISOTROPIC TURBULENCE AND SUPERSONIC CHANNEL FLOW.
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Summary (AI generated)

The discussion began by mentioning that research on reduced rubble and chilly growth was done by Bradshaw in 1977, with increasing convective Mach number. The flow stabilization in the supersonic regime was also studied by Soccer, who had worked together with the speaker in San Diego. Turbulent production was found to decrease along with pressure fluctuations, which is an important quantity in compressible flow. Numerous authors such as Freeman, Sarkar, Fraud, and Pantano have researched this topic.

In supersonic channel flows, there is an increase in anisotropy regarding turbulent stresses, where the stream of stress increases, while the other stresses decrease. The speaker explained that one of the reasons for this is the strong decrease in the pressure strain coalition. The pressure gradient at each point is determined by the momentum transfer of the largest rounding, which is called the vortex region. The speaker explained that this region could be determined using two-point correlations and that it affects pressure fluctuations. The speaker also mentioned that this effective density mapping could be used to show compressive results under incompressible ones.

The pressure strain coalition is an important quantity not only in fresh air flows but also in wall-bounded flow shows. The speaker also discussed how this coalition relates to other types of flows, such as isotropic and psychotropic turbulence. In the speaker's PhD research, gradients with most were examined, and different key quantities transporting patients of the invariants to see how that developed.