3.3 Selected Applications
Many projects performed with AVBP have already been described in the
``Modelling'' chapter 2. The present section only
presents some additional specific examples involving issues related to
numerical techniques and AVBP.
3.3.1 Bio-medical blood flow simulations (JB. Mossa,
F. Nicoud, T. Schönfeld)
Flow simulations in the field of bio-medical applications represent a new
activity explored in 2000
[Nicoud, 2001].
The new integral boundary conditions presented above, have been successfully
applied for the blood flow simulations in cardio-vascular systems such as
the thorax aorta shown in Fig. 3.2.
Figure 3.2: Surface grid of thorax aorta (left) and velocity vectors indicating
a recirculation zone.
3.3.2 Development of a two-phase flow Euler / Euler LES solver
(A. Kaufmann,
JB. Mossa, F. Ducros, B. Cuenot)
The capacities of AVBP for gaseous reacting flows are now sufficiently clear
to recognize that a step must be taken to move to two-phase flows. The choice
CERFACS has been to address this problem from a novel point of view: instead
of using a Lagrangian formulation for droplets and coupling it to the gas
equations, it was decided to write a full Euler Euler code. This involves
first a number of numerical challenges linked to the coupld resolution of the
two phase set of equations. A beta-version of the code resolving the basic
Eulerian/Eulerian compressible transport equations for particles laden flows
has been written in AVBP and tested in 2001, mainly to check numerical
stability issues. Many points have been discussed with O. Simonin (IMFT/EDF).
A more elaborated implementation has been started motivated by an enhanced
interest expressed by industry. The related work will be the basis of the
PRC combustion in collaboration with ONERA-Toulouse: during this program,
Euler / Lagrange (at ONERA) and Euler / Euler formulations (at CERFACS)
will be tested for LES in AVBP. This will also allow comparisons between both
approaches.
3.3.3 LESFOIL -- Unsteady computations over an airfoil
(F. Ducros)
The European LESFOIL project has ended in 2000. During this project many
problems have been investigated: numerical stability for complex geometry
simulation, cross comparisons between wall-resolved and wall-functions for
LES and between structured and unstructured solvers. Most of the results
confirm pioneering results previously obtained at CERFACS
[Weber, 2000]
In particular, it is shown that the use of wall-functions (developed in
both the AVBP and NSMB solvers) yields acceptable results concerning flow
separation, but reveals strong difficulties to deal with transition near
the leading edge.
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