[maHein]

Hello,

I am implementing a solver for the conversion of VoF droplets to Lagrangian particles. Therefore I need to identify all enclosed VoF droplets in order to convert them to particles with equal size / mass / momentum. Beginning with a certain cell, I recursively iterate over every neighbouring cell until I find no more liquid cell (marker_ functions as a variable to distinguish between gas and liquid).

The recursive function looks like the following:

// cellI - label of starting cell
// volID - ID for the resulting enclosed VoF droplet
// marker_ - volScalarField to check for gas (= 0) and liquid (= 1)
// volumeID_ - volScalarField, where connecting liquid cells have the same ID
void checkRecursive(label cellI, const scalar& volID)
{
    // get neighbours of cellI
    const labelList& neighbours = mesh_.cellCells()[cellI];

    // loop over all neighbouring cells of cellI
    forAll(neighbours,i)
    {
        // neighbour cell ID
        label neighbourI = neighbours[i];

        // check if neighbour cell is liquid
        if (marker_[neighbourI] > 0.5)
        {
            // set volume ID
	    volumeID_[neighbourI] = volID;
            // reset marker to avoid infinite loop
	    marker_[neighbourI] = 0.0;

            // repeat check for all neighbours recursively
            checkConnection(neighbourI, volID);
        }
    }
}

This function works up to a certain point (after checking thousands and thousands of cells on large meshes) when suddenly a segmentation fault occurs. Although, up to this point all cell and neighboring labels look reasonable. It looks like OpenFOAM tries to access data which is not available / outside of the stored field ranges. How could that be possible? I am just looking for the neighbors of a given cell?

Does someone has any advise to get rid of that error?

Regards

Martin

[guin]

Originally Posted by maHein

Hello,

I am implementing a solver for the conversion of VoF droplets to Lagrangian particles. Therefore I need to identify all enclosed VoF droplets in order to convert them to particles with equal size / mass / momentum. Beginning with a certain cell, I recursively iterate over every neighbouring cell until I find no more liquid cell (marker_ functions as a variable to distinguish between gas and liquid).

The recursive function looks like the following:

// cellI - label of starting cell
// volID - ID for the resulting enclosed VoF droplet
// marker_ - volScalarField to check for gas (= 0) and liquid (= 1)
// volumeID_ - volScalarField, where connecting liquid cells have the same ID
void checkRecursive(label cellI, const scalar& volID)
{
    // get neighbours of cellI
    const labelList& neighbours = mesh_.cellCells()[cellI];

    // loop over all neighbouring cells of cellI
    forAll(neighbours,i)
    {
        // neighbour cell ID
        label neighbourI = neighbours[i];

        // check if neighbour cell is liquid
        if (marker_[neighbourI] > 0.5)
        {
            // set volume ID
	    volumeID_[neighbourI] = volID;
            // reset marker to avoid infinite loop
	    marker_[neighbourI] = 0.0;

            // repeat check for all neighbours recursively
            checkConnection(neighbourI, volID);
        }
    }
}

This function works up to a certain point (after checking thousands and thousands of cells on large meshes) when suddenly a segmentation fault occurs. Although, up to this point all cell and neighboring labels look reasonable. It looks like OpenFOAM tries to access data which is not available / outside of the stored field ranges. How could that be possible? I am just looking for the neighbors of a given cell?

Does someone has any advise to get rid of that error?

Regards

Martin

Quick question: does it crash when reaching a non-processor boundary?