High Performance Pre- and Post-Processing Equipment for Direct Numerical Simulations (DNS) and Large-Eddy-Simulations of Transitional and Turbulent Flows

1998 ◽  
Author(s):  
Hermann F. Fasel
Keyword(s):  
Numerical Simulations ◽  
Turbulent Flows ◽  
High Performance ◽  
Direct Numerical Simulations ◽  
Large Eddy Simulations ◽  
Post Processing ◽  
Processing Equipment ◽  
Large Eddy

Assessment of the validity of RANS knock prediction using the resonance theory

2019 ◽  
Vol 21 (4) ◽  
pp. 610-621 ◽  
Author(s):  
Corinna Netzer ◽  
Lars Seidel ◽  
Frédéric Ravet ◽  
Fabian Mauss
Keyword(s):  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Large Eddy Simulations ◽  
Navier Stokes ◽  
Post Processing ◽  
Resonance Theory ◽  
Auto Ignition ◽  
Engine Knock ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes

Following the resonance theory by Bradley and co-workers, engine knock is a consequence of an auto-ignition in the developing detonation regime. Their detonation diagram was developed using direct numerical simulations and was applied in the literature to engine knock assessment using large eddy simulations. In this work, it is analyzed if the detonation diagram can be applied for post-processing and evaluation of predicted auto-ignitions in Reynolds-averaged Navier–Stokes simulations even though the Reynolds-averaged Navier–Stokes approach cannot resolve the fine structures resolved in direct numerical simulations and large eddy simulations that lead to the prediction of a developing detonation. For this purpose, an engine operating point at the knock limit spark advance is simulated using Reynolds-averaged Navier–Stokes and large eddy simulations. The combustion is predicted using the G-equation and the well-stirred reactor model in the unburnt gases based on a detailed gasoline surrogate reaction scheme. All the predicted ignition kernels are evaluated using the resonance theory in a post-processing step. According to the different turbulence models, the predicted pressure rise rates and gradients differ. However, the predicted ignition kernel sizes and imposed gas velocities by the auto-ignition event are similar, which suggests that the auto-ignitions predicted by Reynolds-averaged Navier–Stokes simulations can be given a meaningful interpretation within the detonation diagram.

Numerical Simulation of Free-Surface Turbulence

1994 ◽  
Vol 47 (6S) ◽  
pp. S163-S165
Author(s):  
Douglas G. Dommermuth ◽  
Rebecca C. Y. Mui
Keyword(s):  
Numerical Simulation ◽  
Numerical Modeling ◽  
Free Surface ◽  
Numerical Simulations ◽  
Free Surface Flows ◽  
Direct Numerical Simulations ◽  
Large Eddy Simulations ◽  
Surface Flows ◽  
Large Eddy ◽  
Free Surface Turbulence

Direct numerical simulations and large-eddy simulations of turbulent free-surface flows are currently being performed to investigate the roughening of the surface, and the scattering, radiation, and dissipation of waves by turbulence. The numerical simulation of turbulent free-surface flows is briefly reviewed. The numerical, modeling, and hardware issues are discussed.

Parallel Computing: New Power Aids Understanding of Turbulent Flows

2002 ◽  
Author(s):  
Richard H. Pletcher ◽  
Joon S. Lee ◽  
Ning Meng ◽  
Ravikanth Avancha
Keyword(s):  
Turbulent Flows ◽  
First Principles ◽  
High Performance ◽  
Parallel Systems ◽  
Large Eddy Simulations ◽  
Complex Flows ◽  
Complete Understanding ◽  
Significant Challenge ◽  
Eddy Simulation ◽  
Large Eddy

Accurate predictions of turbulent flows occurring in many engineering and environmental applications remain a significant challenge. However, increasing computer power, particularly high performance parallel systems, is enabling more and more complex flows to be solved from first or nearly first principles through direct numerical and large eddy simulation. Such technologies can contribute greatly not only by enabling more accurate predictions but also by revealing details of physics that can contribute to a more complete understanding of turbulence. Several examples where large eddy simulations have provided new details including how rotation and buoyancy alter the structure of turbulence are described.

scholarly journals Unravelling turbulence near walls

2009 ◽  
Vol 630 ◽  
pp. 1-4 ◽  
Author(s):  
IVAN MARUSIC
Keyword(s):  
Laminar Flow ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Turbulent Flows ◽  
Direct Numerical Simulations ◽  
Aircraft Wing ◽  
Physical Mechanisms ◽  
Drag And Lift

Turbulent flows near walls have been the focus of intense study since their first description by Ludwig Prandtl over 100 years ago. They are critical in determining the drag and lift of an aircraft wing for example. Key challenges are to understand the physical mechanisms causing the transition from smooth, laminar flow to turbulent flow and how the turbulence is then maintained. Recent direct numerical simulations have contributed significantly towards this understanding.

scholarly journals Towards practical large-eddy simulations of complex turbulent flows

2009 ◽  
pp. 755-758
Author(s):  
J. Boudet ◽  
A. Cahuzac ◽  
P. Borgnat ◽  
E. Lévêque ◽  
F. Toschi
Keyword(s):  
Turbulent Flows ◽  
Large Eddy Simulations ◽  
Large Eddy
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