Version: 6.5.0
Functions
NonCoincidentDEC

Functions

 ParaMEDMEM::NonCoincidentDEC::NonCoincidentDEC (ProcessorGroup &, ProcessorGroup &)
virtual ParaMEDMEM::NonCoincidentDEC::~NonCoincidentDEC ()
void ParaMEDMEM::NonCoincidentDEC::synchronize ()
void ParaMEDMEM::NonCoincidentDEC::recvData ()
void ParaMEDMEM::NonCoincidentDEC::sendData ()

Detailed Description

Overview

NonCoincidentDEC enables nonconservative remapping of fields between two parallel codes. The computation is possible for 3D meshes and 2D meshes. It is not available for 3D surfaces. The computation enables fast parallel localization, and is based on a point in element search, followed by a field evaluation at the point location. Thus, it is typically faster than the InterpKernelDEC which gives a conservativeremapping. It is particularly true for the initialisation phase (synchronize) which is very computationnaly intensive in InterpKernelDEC.

In the present version, only fields lying on elements are considered. The value is estimated by locating the barycenter of the target side cell in a source cell and sending the value of this source cell as the value of the target cell.

NonCoincident_small.png
Example showing the transfer from a field based on a quadrangular mesh to a triangular mesh. The triangle barycenters are computed and located in the quadrangles. In a P0-P0 interpolation, the value on the quadrangle is then applied to the triangles whose barycenter lies within.
A typical use of NonCoincidentDEC encompasses two distinct phases :

The following code excerpt illutrates a typical use of the NonCoincidentDEC class.

...
NonCoincidentDEC dec(groupA, groupB);
dec.attachLocalField(field);
dec.synchronize();
if (groupA.containsMyRank())
dec.recvData();
else if (groupB.containsMyRank())
dec.sendData();
...

Computing the field on the receiving side can be expressed in terms of a matrix-vector product : $ \phi_t=W.\phi_s$, with $ \phi_t $ the field on the target side and $ \phi_s $ the field on the source side. In the P0-P0 case, this matrix is a plain rectangular matrix with one non-zero element per row (with value 1). For instance, in the above figure, the matrix is :

\[ \begin{tabular}{|cccc|} 1 & 0 & 0 & 0\\ 0 & 0 & 1 & 0\\ 1 & 0 & 0 & 0\\ 0 & 0 & 1 & 0\\ \end{tabular} \]

Function Documentation

ParaMEDMEM::NonCoincidentDEC::NonCoincidentDEC ( ProcessorGroup &  source_group,
ProcessorGroup &  target_group 
)

Constructor of a non coincident DEC with a source group on which lies a field lying on a mesh and a target group on which lies a mesh.

Parameters
source_groupProcessorGroup on the source side
target_groupProcessorGroup on the target side
ParaMEDMEM::NonCoincidentDEC::~NonCoincidentDEC ( )
virtual
void ParaMEDMEM::NonCoincidentDEC::synchronize ( )
virtual

Synchronization process. Calling this method synchronizes the topologies so that the target side gets the information which enable it to fetch the field value from the source side. A typical call is :

  NonCoincidentDEC dec(source_group,target_group);
  dec.attachLocalField(field);
  dec.synchronize();

Implements ParaMEDMEM::DEC.

References MEDMEM::MESH::getBarycenter(), MEDMEM::MESH::getNumberOfElements(), MEDMEM::GMESH::getSpaceDimension(), MEDMEM::FIELD< T, INTERLACING_TAG >::getValue(), and ParaMEDMEM::medmemMeshToFVMMesh().

void ParaMEDMEM::NonCoincidentDEC::recvData ( )

This method is called on the target group in order to trigger the retrieveal of field data. It must be called synchronously with a sendData() call on the source group.

void ParaMEDMEM::NonCoincidentDEC::sendData ( )

This method is called on the source group in order to send field data. It must be called synchronously with a recvData() call on the target group.

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