The traditional method for CFD in industry and universities
is Reynolds-Averaged Navier-Stokes (RANS). Ii is a fast
method and mostly rather accurate. However, in flows
involving large separation regions, wakes and transition it
is inaccurate. The reason is that all turbulence is modeled
with a turbulence model. For predicting aeroacoustic, RANS
is even more unreliable. For these flow, Large-Eddy
Simulation (LES) and Detached-Eddy Simulations (DES) is a
suitable option although it is much more expensive. But in
many industries (automotive, aerospace, gas turbines,
nuclear reactors, wind power) DES is used as an alternative
to RANS. In universities, extensive research has been
carried out during the last decade(s) on LES and DES.
 
Unfortunately, most engineers and many researchers have
limited knowledge of what a LES/DES CFD code is doing. The
object of this course is to close that knowledge gap. During
the course, the participants will learn and work with an
in-house LES/DES code called CALC-LES, written by the
lecturer. It is a finite volume code written in Fortran 77.
It includes two zero-equation SGS models (Smagorinsky and
WALE) and one two-equation model (the PANS model). The
convective terms in the momentum equations are discretized
using central differencing. Hybrid central/upwind is used
for the k and eps equations. The Crank-Nicolson scheme is
used for time discretization of all equations. The numerical
procedure is based on an implicit, fractional step technique
with a multigrid pressure Poisson solver [1] and a
non-staggered grid arrangement. CALC-LES is a single-block
structured code. It is not parallelized. However, it is very
fast. The hump flow (see below), requires less than 4
seconds/time step on a standard PC. For a converged
solutions, 7500+7500 time-steps are sufficient. The number
of cells is 312x120x32.