The source code
/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration |
\\ / A nd | Copyright (C) 2011-2015 OpenFOAM Foundation
\\/ M anipulation |
-------------------------------------------------------------------------------
License
This file is part of OpenFOAM.
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.
OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
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\*---------------------------------------------------------------------------*/
#include "fvCFD.H"
int main(int argc, char *argv[])
{
#include "setRootCase.H"
#include "createTime.H"
#include "createMesh.H"
// For a case being run in parallel, the domain is decomposed into several
// processor meshes. Each of them is run in a separate process and holds
// instances of objects like mesh, U or p just as in a single-threaded (serial)
// computation. These will have different sizes, of course, as they hold
// fewer elements than the whole, undecomposed, mesh.
// Pout is a stream to which each processor can write, unlike Info which only
// gets used by the head process (processor0)
Pout << "Hello from processor " << Pstream::myProcNo() << "! I am working on "
<< mesh.C().size() << " cells" << endl;
// To exchange information between processes, special OpenMPI routines need
// to be called.
// This goes over each cell in the subdomain and integrates their volume.
scalar meshVolume(0.);
forAll(mesh.V(),cellI)
meshVolume += mesh.V()[cellI];
// Add the values from all processes together
Pout << "Mesh volume on this processor: " << meshVolume << endl;
reduce(meshVolume, sumOp<scalar>());
Info << "Total mesh volume on all processors: " << meshVolume
// Note how the reudction operation may be done in place without defning
// a temporary variable, where appropriate.
<< " over " << returnReduce(mesh.C().size(), sumOp<label>()) << " cells" << endl;
// During the reduction stage, different operations may be carried out, summation,
// described by the sumOp template, being one of them.
// Other very useful operations are minOp and maxOp.
// Note how the type
// of the variable must be added to make an instance of the template, here
// this is done by adding <scalar> in front of the brackets.
// Custom reduction operations are easy to implement but need fluency in
// object-oriented programming in OpenFOAM, so we'll skip this for now.
// Spreading a value across all processors is done using a scatter operation.
Pstream::scatter(meshVolume);
Pout << "Mesh volume on this processor is now " << meshVolume << endl;
// It is often useful to check the distribution of something across all
// processors. This may be done using a list, with each element of it
// being written to by only one processor.
List<label> nInternalFaces (Pstream::nProcs()), nBoundaries (Pstream::nProcs());
nInternalFaces[Pstream::myProcNo()] = mesh.Cf().size();
nBoundaries[Pstream::myProcNo()] = mesh.boundary().size();
// The list may then be gathered on the head node as
Pstream::gatherList(nInternalFaces);
Pstream::gatherList(nBoundaries);
// Scattering a list is also possbile
Pstream::scatterList(nInternalFaces);
Pstream::scatterList(nBoundaries);
// It can also be useful to do things on the head node only
// (in this case this is meaningless since we are using Info, which already
// checks this and executes on the head node).
// Note how the gathered lists hold information for all processors now.
if (Pstream::master())
{
forAll(nInternalFaces,i)
Info << "Processor " << i << " has " << nInternalFaces[i]
<< " internal faces and " << nBoundaries[i] << " boundary patches" << endl;
}
// As the mesh is decomposed, interfaces between processors are turned
// into patches, meaning each subdomain sees a processor boundary as a
// boundary condition.
forAll(mesh.boundary(),patchI)
Pout << "Patch " << patchI << " named " << mesh.boundary()[patchI].name() << endl;
// When looking for processor patches, it is useful to check their type,
// similarly to how one can check if a patch is of empty type
forAll(mesh.boundary(),patchI)
{
const polyPatch& pp = mesh.boundaryMesh()[patchI];
if (isA<processorPolyPatch>(pp))
Pout << "Patch " << patchI << " named " << mesh.boundary()[patchI].name()
<< " is definitely a processor boundary!" << endl;
}
// ---
// this is an example implementation of the code from tutoral 2 which
// has been adjusted to run in parallel. Each difference is highlighted
// as a NOTE.
// It is conventional in OpenFOAM to move large parts of code to separate
// .H files to make the code of the solver itself more readable. This is not
// a standard C++ practice, as header files are normally associated with
// declarations rather than definitions.
// A very common include, apart from the setRootCase, createTime, and createMesh,
// which are generic, is createFields, which is often unique for each solver.
// Here we've moved all of the parts of the code dealing with setting up the fields
// and transport constants into this include file.
#include "createFields.H"
// pre-calculate geometric information using field expressions rather than
// cell-by-cell assignment.
const dimensionedVector originVector("x0", dimLength, vector(0.05,0.05,0.005));
volScalarField r (mag(mesh.C()-originVector));
// NOTE: we need to get a global value; convert from dimensionedScalar to scalar
const scalar rFarCell = returnReduce(max(r).value(), maxOp<scalar>());
scalar f (1.);
Info<< "\nStarting time loop\n" << endl;
while (runTime.loop())
{
Info<< "Time = " << runTime.timeName() << nl << endl;
// assign values to the field;
// sin function expects a dimensionless argument, hence need to convert
// current time using .value().
// r has dimensions of length, hence the small value being added to it
// needs to match that.
// Finally, the result has to match dimensions of pressure, which are
// m^2 / s^-2/
p = Foam::sin(2.*constant::mathematical::pi*f*runTime.time().value())
/ (r/rFarCell + dimensionedScalar("small", dimLength, 1e-12))
* dimensionedScalar("tmp", dimensionSet(0, 3, -2, 0, 0), 1.);
// NOTE: this is needed to update the values on the processor boundaries.
// If this is not done, the gradient operator will get confused around the
// processor patches.
p.correctBoundaryConditions();
// calculate velocity from gradient of pressure
U = fvc::grad(p)*dimensionedScalar("tmp", dimTime, 1.);
runTime.write();
}
Info<< "End\n" << endl;
return 0;
}
// ************************************************************************* //
The results
/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 6
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
Build : 6
Exec : ofTutorial5 -parallel
Date : Apr 06 2019
Time : 23:50:53
Host : "zhoudq-MacBookAir"
PID : 6003
I/O : uncollated
Case : /home/zhoudq/OpenFOAM/BasicOpenFOAMProgrammingTutorials/OFtutorial05_basicParallelComputing/testCase
nProcs : 4
Slaves :
3
(
"zhoudq-MacBookAir.6004"
"zhoudq-MacBookAir.6005"
"zhoudq-MacBookAir.6006"
)
Pstream initialized with:
floatTransfer : 0
nProcsSimpleSum : 0
commsType : nonBlocking
polling iterations : 0
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time
Create mesh for time = 0
[0] Hello from processor 0! I am working on 100 cells
[0] Mesh volume on this processor: 2.5e-05
[1] Hello from processor 1! I am working on 100 cells
[2] Hello from processor 2! I am working on 100 cells
[2] Mesh volume on this processor: 2.5e-05
[1] Mesh volume on this processor: 2.5e-05
[3] Hello from processor 3! I am working on 100 cells
[3] Mesh volume on this processor: 2.5e-05
Total mesh volume on all processors: 0.0001 over 400 cells
[0] Mesh volume on this processor is now 0.0001
[3] Mesh volume on this processor is now 0.0001
[2] Mesh volume on this processor is now 0.0001
[1] Mesh volume on this processor is now 0.0001
Processor 0 has 175 internal faces and 4 boundary patches
Processor 1 has 175 internal faces and 5 boundary patches
Processor 2 has 175 internal faces and 5 boundary patches
Processor 3 has 175 internal faces and 4 boundary patches
[0] Patch 0 named movingWall
[0] Patch 1 named fixedWalls
[0] Patch 2 named frontAndBack
[0] Patch 3 named procBoundary0to1
[0] Patch 3 named procBoundary0to1 is definitely a processor boundary!
Reading transportProperties
[1] Patch 0 named movingWall
[1] Patch 1 named fixedWalls
[3] Patch 0 named movingWall
[3] Patch 1 named fixedWalls
[2] Patch 0 named movingWall
[2] Patch 1 named fixedWalls
[2] Patch 2 named frontAndBack
[2] Patch 3 named procBoundary2to1
[2] Patch 4 named procBoundary2to3
[2] Patch 3 named procBoundary2to1 is definitely a processor boundary!
[2] Patch 4 named procBoundary2to3 is definitely a processor boundary!
[1] Patch 2 named frontAndBack
[3] Patch 2 named frontAndBack
[3] Patch 3 named procBoundary3to2
[3] Patch 3 named procBoundary3to2 is definitely a processor boundary!
[1] Patch 3 named procBoundary1to0
[1] Patch 4 named procBoundary1to2
[1] Patch 3 named procBoundary1to0 is definitely a processor boundary!
[1] Patch 4 named procBoundary1to2 is definitely a processor boundary!
Reading field p
Reading field U
Starting time loop
Time = 0.1
Time = 0.2
Time = 0.3
Time = 0.4
Time = 0.5
Time = 0.6
Time = 0.7
Time = 0.8
Time = 0.9
Time = 1
End
Finalising parallel run
