472ce5ace6
used in conjunction with the new loadBalancing option in constant/chemistryProperties:
loadBalancing on;
which enables per-cell CPU time caching used by the loadBalancer to redistribute
the mesh. Currently this option is only provided for chemistry integration but
the implementation is general and in future options will be provided to balance
other local cell loads, in particular Lagrangian particles.
The loadBalancer in enabled by specifying a distributor entry in
constant/dynamicMeshDict, e.g.
distributor
{
type loadBalancer;
libs ("libfvMeshDistributors.so");
multiConstraint true;
// How often to redistribute
redistributionInterval 10;
// Maximum fractional cell distribution imbalance
// before rebalancing
maxImbalance 0.1;
}
with which the mesh is checked for more than 10% load-imbalance every 10
time-steps and redistributed using a multi-constraint method, i.e. separate CPU
load weights are provided for each of the loads, currently that is the chemistry
integration load and the CPU time taken for the rest of the simulation,
transport equations solution etc.
The fvMeshDistributors::loadBalancer uses the distributor specified in
system/decomposeParDict to redistribute the mesh based on the cell CPU loads,
e.g. to use the Zoltan RCB method specify:
distributor zoltan;
libs ("libzoltanDecomp.so");
zoltanCoeffs
{
lb_method rcb;
}
Unfortunately only a few available redistribution methods support
multi-constraints: Zoltan::RCB, MeTiS, parMeTiS and xtraPuLP, of these only
Zoltan::RCB is currently available in OpenFOAM. Load-balancing is possible
without using a multi-constraint method (i.e. using any of the other
decomposition methods provided with OpenFOAM and Zoltan) by summing the various
CPU loads which is selected by setting:
multiConstraint false;
but the load-balancing is likely to be a lot less effective with this option.
Due to the licencing issues with parMeTiS interfacing to xtraPuLP might be the
best option for further work on load-balancing in OpenFOAM, or MeTiS could be
used in parallel by first agglomerating the distribution graph on the master
processor and redistributing the result; this pseudo-parallel option is already
provided for the Scotch method.
README for OpenFOAM-dev
- About OpenFOAM
- Copyright
- Download and installation instructions
- Documentation
- Source code documentation
- OpenFOAM C++ Style Guide
- Reporting bugs in OpenFOAM
- Contacting the OpenFOAM Foundation
#
About OpenFOAM
OpenFOAM is a free, open source computational fluid dynamics (CFD) software package released by the OpenFOAM Foundation. It has a large user base across most areas of engineering and science, from both commercial and academic organisations. OpenFOAM has an extensive range of features to solve anything from complex fluid flows involving chemical reactions, turbulence and heat transfer, to solid dynamics and electromagnetics.
Copyright
OpenFOAM is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version. See the file COPYING in this directory or
http://www.gnu.org/licenses/, for a description of the GNU General Public
License terms under which you can copy the files.