3 Unsteady Flow Calculations on Hybrid Grids -- The AVBP Project
This project covers the unsteady flow activities of the CFD team on
unstructured and hybrid grids. These studies are mainly based on the CERFACS
in-house solver AVBP, which is a parallel finite-volume CFD solver of the
compressible Navier-Stokes equations. Structured, unstructured or hybrid
grids are handled for 2-D, 3-D and axi-symmetric configurations. AVBP is
primarily used to solve problems in the fields of unsteady turbulence and
combustion. Through these activities the AVBP project is strongly interlinked
to the ``Modeling'' project of the CFD-group. Since the modelling aspects of
many of these projects have already been described in the ``Modeling''
chapter 2, this part focuses on numerical issues.
The success of the AVBP project was confirmed in 2000 and 2001 by several
facts of both academical and more applied nature resulting in several
publications in CFD journals
[Colin, 2000;
Colin, 2000a;
Schlüter, 2000]
and the PhD-thesis defenses of O. Colin
[Colin, 2000 PhD],
J. Schlüter [Schlüter, 2000 PhD]
and J.P. Légier [Légier, 2001 PhD].
The participation of CERFACS with AVBP to the turbulence summer program
at Stanford University represents a second major scientifical event
[Légier, 2000].
On the industrial side the current contract with Siemens KWU has ended in
2000 to an overall satisfaction of both partners, which has resulted in a
follow-on project of similar size in 2001. Discussions with SNECMA and
Turbomeca have lead to the selection of AVBP as the main LES code in the
PRC Combustion, a national program funded by DGA. This confirms the interest
in AVBP expressed by French gas turbine manufacturers to perform LES. Similar
discussions are underway with Institut Francais du Pétrole and PSA to use
AVBP for LES in piston engines.
Two-phase flows are now becoming one of the essential research topics for
AVBP. CERFACS shareholder EDF has manifested his interest through a Ph.D.
thesis conducted in the field of two-phase flows. The new PRC combustion
discussed above also focuses on LES for two-phase flows. On a more political
level, a decisio was made at ONERA to evaluate the capabilities of AVBP and
to collaborate on two-phase flows: the code was delivered and installed in
Toulouse and Chatillon in 2000. Finally, preliminary activities in the
challenging domain of bio-medical blood flow simulations (conducted in
collaboration with Toulouse University Hospital) has broadened the
application spectrum of the AVBP solver.
Current bilateral links to industry have been pursued with EADS Missiles
Division, SNECMA, SEP and Siemens KWU in Germany, while contacts with
Alstom Power in Switzerland have resulted in a PhD thesis started in 2001
and two additional PhD in the framework of the EC project Fuelchief accepted
in 2001. Therefore, the AVBP solver is now employed in multiple ongoing FP'5
European Programmes. Finally, the code is proposed as module of the hands-on
training course for final year master students in fluid mechanics at ENSEEIHT
engineering school in Toulouse.
These increasing activities have resulted in the beginning of four new Ph.D.
students at CERFACS in 2000 and six in 2001 together with the opening of a
first software support engineering position. In 2001, more than 25 people
were working full-time on AVBP, amongst them 15 PhD theses at CERFACS,
Institut Français du Pétrole, IMFT and Ecole Centrale Paris. The overall
code management and integration tasks are centralized at CERFACS.
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