DNS and LES for investigating transition and transition control

Fasel, Hermann F.; Meitz, Hubert L.; Bachman, C. R.

doi:10.2514/6.1997-1820

Cited by 10 publications

(4 citation statements)

References 21 publications

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“…Second, if properly implemented, the wall vorticity can be calculated with the full spatial and temporal accuracy of the numerical scheme. This approach has been successfully applied to simulations of transition 8, 9, 10] as well as turbulent ows for a simple geometry 11,12]. When the geometry becomes more complex (such as the ow over a curved wall), the transition processes and turbulence production mechanisms are more complicated.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of the turbulent flow over a Stratford ramp

Zhang

Fasel

1999

14th Computational Fluid Dynamics Conference

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A numerical method is presented for Direct Numerical Simulations (DNS) of a turbulent boundary layer ow over a curved wall. The incompressible, unsteady Navier-Stokes equations in vorticityvelocity formulation and curvilinear coordinates are solved using compact di erences of fourth order accuracy and a fourth-order Runge-Kutta method. The resulting DNS code with a curved wall capability is compatible in code structure with a Cartesian version of Meitz and Fasel 3], from which the new code was developed. The computational eciency is also comparable to the Cartesian version. Employing this new code the turbulent boundary layer ow on a Stratford ramp was simulated. It was found that (1) a boundary layer with both strong adverse pressure gradient and curvature can be maintained close to separation over an extended distance of the Stratford ramp; and (2) the ow displays strong non-equilibrium e ects, and thus would require more advanced turbulence models for Reynolds Averaged Navier-Stokes calculations. The present numerical results agree well with experimental measurements from Elsberry et al. 15]. Research Associate. Member AIAA. y Professor, Aerospace and Mechanical Engineering. Member AIAA.

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Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of the turbulent flow over a Stratford ramp

Zhang

Fasel

1999

14th Computational Fluid Dynamics Conference

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“…The LES version of our code is discussed by Fasel et al [12]. This code was originally developed for transitional and turbulent boundary layers with adverse pressure gradient.…”

Section: Large-eddy Simulationmentioning

confidence: 99%

Numerical investigation of forced transitional wall jets

Wernz

Easel

1997

28th Fluid Dynamics Conference

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Direct numerical simulations (DNS) based on the incompressible Navier-Stokes equations are employed to investigate secondary instability mechanisms in a forced transitional wall jet. Our simulations indicate that in addition to a commonly known two-dimensional subharmonic resonance associated with the outer free shear layer region of the wall jet, three-dimensional fundamental and subharmonic resonances associated with the nearwall boundary layer region may play a role in the transition process as well. For example, twodimensional vortical structures in the near-wall region can be weakened enough through moderate three-dimensional forcing that ejection of vortex pairs from the wall into the ambient fluid is prevented. Similar observations have been made in large-eddy simulations (LES) of a bypass transition process where (random in time) large amplitude three-dimensional forcing is applied. Vortical structures with a strong spanwise coherence are observed in the outer region of the wall jet, but the near-wall region remains predominantly three-dimensional.

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“…Also, the code used for our Large-Eddy Simulations using the Smagorinsky model has been tested for numerous flow configurations ( see e.g. Fasel et al, 1997). However, the code extensions required for our URANS calculations and the new FSM needed to undergo a series of benchmark calculations.…”

Section: Validation Of the New Fsmmentioning

confidence: 99%

Control of Separation Using Pulsed Wall Jets: Numerical Investigations Using DNS and LES

Fasel¹

2000

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DNS and LES for investigating transition and transition control

Cited by 10 publications

References 21 publications

Direct numerical simulations of the turbulent flow over a Stratford ramp

Direct numerical simulations of the turbulent flow over a Stratford ramp

Numerical investigation of forced transitional wall jets

Control of Separation Using Pulsed Wall Jets: Numerical Investigations Using DNS and LES

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