The Incremental Unknowns - a multilevel scheme for
the simulation of turbulent channel flows
In numerical simulation of complex flows,
it is important to identify different length scales of the
flow and treat them differently. In this report, we introduce
a new multilevel scheme for simulating turbulent channel
flows. Two different versions of the scheme, namely the spectral and finite
difference versions, are presented.
The spectral version of the scheme
is based on a spectral-Galerkin formulation which provides
a natural decomposition of the flow into small and large wavelength parts,
and which leads to linear systems that can be solved with quasi-optimal
In the finite difference version,
the ``Incremental Unknown'' (IU) is used to separate the length scales.
Preliminary numerical results indicate that the
scheme is well suited for turbulence computations and provides
results which are comparable to that by Direct Numerical Simulation but with
significantly less CPU time.
Min Chen (firstname.lastname@example.org)