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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS        
                   School of Computational Sciences	
                           (CSI 898-Sec 001) 
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          On the Numerical Simulation of High Reynolds-Number 
                      Inhomogeneous Flows 

                     Fernando F. Grinstein

      Laboratory for Computational Physics & Fluid Dynamics
           Naval Research Laboratory, Washington, DC 

The ability to predict practical complex flows is limited by the 
current state-of-the art of Sub Grid Scale (SGS) modeling, which 
invariably relies on the use of isotropic eddy-viscosity models. 
Turbulent flows of practical importance involve inherently 
three-dimensional unsteady features, often subjected to strong 
inhomogeneous effects and rapid deformation which can not be captured 
by isotropic models. Although other available SGS models outperform 
the isotropic eddy-viscosity model, their usefulness is limited due 
to their high computational cost, and it is therefore desirable to 
also explore the use of alternative non-conventional models. In 
ordinary Large Eddy Simulation (LES) approaches models are introduced 
for closure in the low-pass filtered Navier Stokes Equations (NSE). A 
promising LES approach is Monotonically Integrated LES (MILES), which 
involves solving the unfiltered NSE using high-resolution monotone 
algorithms; in this approach, implicit SGS models, provided by 
intrinsic non-linear high-frequency filters built into the convection 
discretization are coupled naturally to the resolvable scales of the 
flow. Mathematical and physical aspects of (implicit) SGS modeling 
through the use of non-linear flux-limiters are addressed using a 
formalism based on the modified equations. Analysis of the effectual 
SGS modeling using MILES is presented using databases of simulated 
free and wall-bounded flows, including homogeneous turbulence, 
transitional jets, and channel flows. Review of recent MILES of 
turbulent jets focuses on the newly acquired understanding on the 
dynamics and topology of coherent structures characterizing 
rectangular jet flows, and their effects on near jet entrainment and 
non-premixed combustion.

                        Monday , February 26, 2001
                                  4:30 pm
                        Room 206, Science & Tech. I

Refreshments will be served at 4:15 PM.
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Find the schedule at http://csi.gmu.edu/lcdm/seminar/schedule.html