Possible bug in twoWayMPI giveData / getData

Dear,

I have noticed some weird behavior when transferring data between LIGGGHTS and OpenFOAM.

I have adjusted one of the solvers to modify some custom atom properties in OpenFOAM and then sending those modified properties back to LIGGGHTS to be transported there together with the particles. So basically, in every CFD time step, I do the following:

// getting data from LIGGGHTS
particleCloud_.dataExchangeM().getData(partFieldName_, "scalar-atom", partField_);
// modifications to partField
for(int index = 0; index < particleCloud_.numberOfParticles(); ++index) partField_[index][0] = ...;
// sending modified data back to LIGGGHTS
particleCloud_.dataExchangeM().giveData(partFieldName_, "scalar-atom", partField_);


However, the values that are received by LIGGGHTS are not the same as those that I send via giveData.
To make sure that this is not related to a bug in my own code, I also tested it by adjusting the commToDEM function in the LaEuScalarTemp forceModel. More specifically, I added a few giveData/getData commands immediately after each other and the first element of the heat flux is printed after each giveData/getData call:

particleCloud_.dataExchangeM().giveData(partHeatFluxName_, "scalar-atom", partHeatFlux_);
Info << "gave partHeatFlux_[0][0] = " << partHeatFlux_[0][0] << endl;
particleCloud_.dataExchangeM().getData(partHeatFluxName_, "scalar-atom", partHeatFlux_);
Info << "got partHeatFlux_[0][0] = " << partHeatFlux_[0][0] << endl;
particleCloud_.dataExchangeM().giveData(partHeatFluxName_, "scalar-atom", partHeatFlux_);
Info << "gave partHeatFlux_[0][0] = " << partHeatFlux_[0][0] << endl;
particleCloud_.dataExchangeM().getData(partHeatFluxName_, "scalar-atom", partHeatFlux_);
Info << "got partHeatFlux_[0][0] = " << partHeatFlux_[0][0] << endl;
particleCloud_.dataExchangeM().giveData(partHeatFluxName_, "scalar-atom", partHeatFlux_);
Info << "gave partHeatFlux_[0][0] = " << partHeatFlux_[0][0] << endl;
particleCloud_.dataExchangeM().getData(partHeatFluxName_, "scalar-atom", partHeatFlux_);
Info << "got partHeatFlux_[0][0] = " << partHeatFlux_[0][0] << endl;


By doing so, the output of the packedBedTemp tutorial in the first time step is as below. Clearly, although the first giveData seems to work properly, it messes up after 2 calls. I noticed that the values are often off by a factor equal to the number of processors used by the simulations, although this is not always the case for my own code.

gave partHeatFlux_[0][0] = -1.20515
got partHeatFlux_[0][0] = -1.20515
gave partHeatFlux_[0][0] = -1.20515
got partHeatFlux_[0][0] = -2.41031
gave partHeatFlux_[0][0] = -2.41031
got partHeatFlux_[0][0] = -4.82061
gave partHeatFlux_[0][0] = -4.82061
got partHeatFlux_[0][0] = -9.64123


Has somebody experienced the same issue? Is this a bug or am I doing something wrong?

Thanks,
Laurien