The parallel inhouse research CFD CAA code NOISETTE



Institute for Mathematical Modelling (IMM) of Russian Academy of Science (RAS)

 Explicit highorder algorithms for unstructured 2D (triangular) and 3D (tetrahedral) meshes
 DNS of compressible viscous flows and aeroacoustics (DNC, NLDE)
 High efficiency on thousands of CPUs of a supercomputer even for small meshes
 Hybrid MPI+OpenMP parallelization
 Language: computational part  Fortran 90, infrastructure  C++

Authors: I. Abalakin, A. Gorobets, T. Kozubskaya, D. Kolmogorov, A. Duben, I. Borovskaya
Original sequential 2D version designed in IMM RAS together with INRIA, SophiaAntipolis, France
(Abalakin I. V., Kozubskaya T. K., A. Dervieux, C. Debiez)

Mathematical basis
 Euler Equations (EE)
 NavierStokes Equations (NSE)
 Nonlinear Disturbances Equations (NLDE)
 Linearized Euler Equations (LEE)
 Linearized NavierStokes Equations (NSE)

Numerical Techniques Implemented
Space Approximation
Multiparameter vertexcentered scheme (up to 6th order)
Time Integration
RungeKutta method, Lowstorage RungeKutta method (up to 4th order)
Linear Lowstorage RungeKutta method (arbitrarily high order)
Boundary Conditions
StegerWarming flux splitting based inflow and outflow BC
Characteristic BC
Nonreflecting (radiation and outflow, buffer zones)
Nonlocal transparent BC

Parallel performance

Parallel algorithm is based on a hybrid MPI+OpenMP approach which better fits modern architecture of a supercomputer with multicore nodes.
Following figures demonstrate high parallel efficiency even for a small problem.
The high order scheme with the large space stencil is used in the tests.

Supercomputer MVS 100000 (JSC RAS)
Mesh size is only ~10^{6} nodes

Supercomputer Lomonosov (MSU)
Mesh size 1.6*10^{7} nodes

Current applications
 Numerical experiments on acoustic liners (Jet engine noise reduction devices)
 Optimization of acoustic sensors for mobile robots
 Modeling of impedance tubes with resonator chambers
 Complex flows around obstacles considering acoustic effects
Development directions
 General objectoriented restructuring of the code (Gorobets, Kozubskaya)
 Implementation of turbulence models RANS, DES, LES (Abalakin, Kolmogorov)
 Implicit time integration algorithm (Abalakin, Kolmogorov)
 Parallel algorithm improvements (Gorobets)
 New types of boundary conditions  periodic BC, nonlocal BC, etc.
 Infrastructure extension


Publications:
 A.V.Gorobets, T.K.Kozubskaya, “Technology of parallelization of the explicit highaccuracy algorithms for CFD and CAA on nonstructured meshes”, Mathematical modeling, vol. 19, number 2, pp. 6886, 2007
 A.V. Gorobets, I.V. Abalakin, T.K. Kozubskaya, “Technology of parallelization for 2D and 3D CFD/CAA codes based on highaccuracy explicit methods on unstructured meshes”, Parallel CFD 2007, Antalya (Turkey), May 2007
 Abalakin I.V., Dervieux A., Kozubskaya T.K. "High Accuracy Finite Volume Method for Solving
Nonlinear Aeroacoustics Problems on Unstructured Meshes", Chinese Journal of Aeronautics,
Vol. 19, No 2, 2006.
 Tatiana K. Kozubskaya, "Validation and Verification in Computational Aeroacoustics:
from Linear to Nonlinear"  In A series of Handbooks on Theory and Engineering Applications of Computational Methods. Verification and Validation Methods for Challenging Multiphysics Problems, CIMNE, Barcelona (2006), pp. 187208

