Large-eddy simulation of transition and turbulence in wall-bounded shear flow

203 Pages·2005·11.69 MB·English

by  Schlatter P.

Research Collection
Doctoral Thesis
Large-eddy simulation of transition and turbulence in wall-
bounded shear flow
Author(s):
Schlatter, Philipp Christian
Publication Date:
2005
Permanent Link:
https://doi.org/10.3929/ethz-a-004945776
Rights / License:
In Copyright - Non-Commercial Use Permitted
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ETH Library
LARGE-EDDY SIMULATION OF
TRANSITION AND TURBULENCE
IN WALL-BOUNDED SHEAR FLOW
Philipp Schlatter
Dissertation ETH No. 16000

Visualisation taken from a large-eddy simulation (LES) of spatial K-type
transition in plane channel flow. Shown are isosurfaces of the negative-λ
2
vortex-identification criterion. The two-dimensional wave disturbances
(yellow isosurfaces) at the inlet break down to turbulence through the
formation of Λ-vortices and hairpin vortices (red isosurfaces). A turbu-
lent spot (white) is formed which evolves into fully developed turbulent
channel flow further downstream (green). The colored bottom wall shows
the skin friction, the rear side wall displays the spanwise vorticity in the
valley plane.

Diss. ETH No. 16000
LARGE-EDDY SIMULATION OF
TRANSITION AND TURBULENCE IN
WALL-BOUNDED SHEAR FLOW
A dissertation submitted to the
SWISS FEDERAL INSTITUTE OF TECHNOLOGY
¨
ZURICH
for the degree of
Doctor of Technical Sciences
presented by
Philipp Christian Schlatter
Dipl. Ing. ETH (Swiss Federal Institute of Technology Zu¨rich)
born on May 21, 1975
citizen of Zu¨rich (ZH)
accepted on the recommendation of
Prof. Dr. L. Kleiser, examiner
Prof. Dr. N. D. Sandham, co-examiner
2005

Abstract
Large-eddy simulations (LES) of transitional and turbulent wall-
bounded incompressible flow have been performed. A special focus
has been on the reliable and efficient modelling of laminar-turbulent
transition in plane channel flow at low resolutions, for which several
subgrid-scale (SGS) models have been evaluated, including the approxi-
mate deconvolution model (ADM) and related approaches, classical and
high-pass filtered (HPF) eddy-viscosity models, and dynamic models.
The simulations have been performed in both the temporal and spatial
transition framework.
The results show that a direct modelling involving a relaxation reg-
ularisation (ADM-RT model) provides the most accurate results for
both transitional quantities and turbulent statistics. By use of three-
dimensional visualisation of instantaneous flow structures it is inves-
tigated how well the SGS models on coarse grids are able to predict
the physically relevant mechanisms at successive stages of transition:
Λ-vortices, rollup of shear layers, and hairpin vortices. The results
show that the ADM-RT model predicts similar transitional structures as
present in fully resolved direct numerical simulation (DNS) data, how-
ever using less than one percent of the numerical resolution of the latter.
Other SGS models are not capable of predicting these physical structures
at the chosen coarse resolution.
Additionally, the different SGS models have been examined in homo-
geneous isotropic turbulence. The models provide an accurate prediction
of the energy and dissipation spectra even for high Reynolds numbers.
A Fourier method based on a windowing approach to prescribe non-
periodic inflow and outflow boundary conditions has been formulated
and evaluated. Test cases involving a travelling vortex core and a spa-
tially developing jet have shown very good outflow damping properties.
The spectral accuracy of the underlying numerical scheme is retained.
The windowing approach has been compared to the well-established
fringe method.
Kurzfassung
Large-Eddy-Simulationen (LES) von transitionellen und turbulenten
wandbegrenzten inkompressiblen Stro¨mungen wurden durchgefu¨hrt.
Spezielle Beachtung fand dabei die verl¨assliche und effiziente Model-
lierung der laminar-turbulenten Transition in ebener Kanalstro¨mung
bei geringer Auflo¨sung. Es wurden verschiedene Turbulenzmodelle
untersucht, insbesondere das “Approximate Deconvolution Model”
(ADM) und verwandte Ansa¨tze, klassische und hochpassgefilterte
Wirbelviskosita¨tsmodelle (eddy-viscosity models), einschliesslich des
bekannten dynamischen Modells. Die Simulationen wurden sowohl
in ra¨umlicher als auch zeitlicher Betrachtungsweise der Transition
durchgefu¨hrt.
Die Resultate zeigen, dass eine direkte Modellierung basierend auf
einer Regularisierung mittels eines Relaxationsterms die genauesten Re-
sultate sowohl fu¨r transitionelle Gro¨ssen als auch fu¨r turbulente Statis-
tiken liefert. Dreidimensionale Visualisierungen zeigen ausserdem, ob
und wie die verschiedenen Modelle die charakteristischen Stufen der
Transition wiedergeben: Λ-Wirbel, Aufrollen der Scherschichten und
Haarnadelwirbel. Die Resultate zeigen weiter, dass das ADM-RT-Modell
sehr ¨ahnliche Strukturen wie die vollaufgelo¨sten Daten der direkten nu-
merischen Simulation (DNS) vorhersagt, obwohl weniger als ein Prozent
der Gitterauflo¨sung verwendet wurde. Andere Modelle waren hingegen
bei der gew¨ahlten niedrigen Auflo¨sung nicht in der Lage, diese Struk-
turen vorherzusagen.
Zusa¨tzlich wurden die verschiedenen Modelle auch in homogener
isotroper Turbulenz untersucht. Es zeigte sich, dass sie eine genaue
Voraussage der Energie- als auch der Dissipationsspektren auch fu¨r hohe
Reynoldszahlen erlauben.
Eine Fouriermethode basierend auf einem Windowing-Ansatz wurde
zur Aufpra¨gung von Ein- und Ausflussbedingungen formuliert und be-
wertet. Testf¨alle mit einem Wirbel und einem sich ra¨umlich entwi-
ckelnden Freistrahl (Jet) zeigten gute D¨ampfungseigenschaften am Aus-
flussrand. Die spektrale Genauigkeit des zugrundeliegenden numerischen
Verfahrens bleibt erhalten. Die Windowing-Methode wurde verglichen
mit der etablierten Fringe-Methode.
Acknowledgements
I would like to thank Prof. Leonhard Kleiser for supervising my research
at the Institute of Fluid Dynamics (IFD) of ETH Zu¨rich. His constant
support, deep understanding and interest in the fields of numerics, tran-
sition, and turbulence were of indispensable value and help. He also
made it possible for me to attend a number of international conferences,
an experience I do not want to miss.
I also like to thank Prof. Neil Sandham (University of Southhampton)
for agreeing to be co-examiner for my PhD thesis.
I am particularly grateful to Dr. Steffen Stolz (ETH) for his tireless
support and enormous patience in explaining me everything necessary
about numerics, turbulence, and large-eddy simulation, and for correct-
ing and improving my reports. Without his experienced advice and
constant interest this work could certainly not have been accomplished.
The support of Prof. Nikolaus Adams at the beginning of this re-
search project is also thankfully acknowledged.
Furthermore, I am indepted to Prof. Dan Henningson (KTH Stock-
holm) for giving me the possibility to spend a short period in Sweden to
continue our collaboration on bypass transition. In particular, I would
like to thank Dr. Luca Brandt (KTH) for alwayshelping me in case of any
questions about transition or stability. I also like to thank Dr. Benjamin
Rembold (ETH) and Mr. Jo¨rg Ziefle (ETH) for stimulating discussions
on, but not only on, fluid dynamics. Dr. Thorsten Bosse is acknowl-
edged to bear me during the three years as office mate at the Institute.
I also would like to thank Mr. Hans Peter Caprez (ETH) for providing a
reliable computer environment and for satisfying all my special requests.
I would also like to thank my friends for their support during the
good and also during the busy times of my PhD project.
This work was supported by the Swiss National Science Foundation
(SNF) and the Swiss National Supercomputing Centre (CSCS), Manno.
Calculations have been performed at CSCS.
Zu¨rich, March 2005 Philipp Schlatter