Plane channel flow
The following documents are related to the generation of a time-series
of flow fields in turbulent plane channel flow, i.e. the
pressure-driven flow between two parallel walls of infinite
extension. Our simulations reach a friction-velocity based Reynolds
number of up to Retau=590. In general our box size is 2pih×pih in the wall-parallel plane, where 2h is the distance
between the walls. The simulation code is based upon sources kindly
provided by J. Jiménez and A. Pinelli of U. Politécnica Madrid,
Spain.
- A plane channel flow transition experiment. An abstract is
available in
html. The
main document is in pdf format.
- A detailed description (in German) of the parallelism of our DNS
code is given in this application for computing time:
"Projektbeschreibung zum Grossprojektantrag fuer den Parallelrechner
T3E des ZIB". An abstract (in English) is available in
html. The
main document is in pdf format.
- Is there a need for de-aliasing in a Chebyshev pseudo-spectral
method? A priori, yes, but in practice this issue is often not
discussed. We take a look at this issue, with an abstract in
html
and the main document as pdf.
- Here is a description of how the initial fields for our series
were generated; abstract in
html
and main document as
pdf.
- The series of flow fields itself is documented here: parameters,
statistics, computational details and visualizations.
- The main document as
pdf.
- Some images of instantaneous data in wall-parallel planes at
Retau=590 and at very high resolution are available in
png
format.
- For the above case, there is an animation of the buffer-layer
streaks. i.e. iso-surfaces of velocity fluctuations at u'+=±4
in the layer where 0 <= y+ <= 50. MPEG format
(2.2MB),
GIF
format (17MB).
- The corresponding animation of log-layer streaks shows
iso-surfaces of velocity fluctuations at u'+=±3
in the layer where 50 <= y+ <= 300. MPEG format
(3MB),
GIF
format (17MB) (or, alternatively, the corresponding sequence
recorded near the opposite wall:
MPEG,
GIF).
- Analogously, there is an animation of the so-called swirling strength [11], which helps to visualize what
one commonly understands as vortices by not reacting in regions
of pure shear. More specifically, we visualize iso-surfaces of
lambdaci2, where lambdaci is the imaginary part of
the complex conjugate pair of eigenvalues of the velocity gradient
tensor ui,j in regions where its discriminant is
positive. The value shown corresponds to approx. 10% of the
maximum. In the movie - in
MPEG format at
900x675 pixels (15MB) - one can clearly distinguish and follow
cane-vortices, hairpins at all stages and clusters of hairpins (or
hairpin packets).
markus.uhlmann AT kit.edu
