[EZS]

Hello everyone

I'm using OpenFOAM-6 with chtMultiRegionFoam to run transient simulations.
The case is basically a pipe with a specific inlet and outlet geometry. The simulation runs perfectly fine, but I need help with runtime post-processing the results.

I need to calculate the average temperature and pressure at multiple locations along the pipe. Therefore I used a function object in the controlDict to calculate the area average like this:

avgPlane
{
	type			surfaceFieldValue;
	libs			("libfieldFunctionObjects.so");
	region			fluid;
	writeControl		runTime;
	writeInterval		0.005;
	writeFields		false;
	regionType		sampledSurface;
	name			"surf000";
	operation		areaAverage;
	sampledSurfaceDict
	{
		type		plane;
		planeType	pointAndNormal;
		pointAndNormalDict
		{
			basePoint	(0 0 0.5);
			normalVector	(0 0 1);
		}
	}
	fields			(T p Uz k);
}

This works as intended, but now I want to calculate the mass flow average. According to the documentation I can achieve this with the following changes:

	operation	weightedAverage;
	weightField	phi;

The weightedAverage is not compatible with the sampledSurface though. There are 3 different values for regionType to choose from:

1. sampledSurface this doesn't work, because you "Cannot use weightField for a sampledSurface".
2. faceZone. I created a faceZone using searchableSurfaceToFaceZone, but OpenFOAM is "Unable to process internal faces for volume field T".
3. patch. As far as I understand I cannot create a patch at any location, as this would influence the mesh, right?

I have looked through many threads in this forum and didn't find a solution to my problem. Here wyldckat suggests to use a baffle, but this would also influence my mesh.
Can anyone help me to calculate a mass flow average at an arbitrary location?

[EZS]

Can anyone help me here? I still have not found a solution.

[olesen]

Originally Posted by EZS

Can anyone help me here? I still have not found a solution.

If you can move to a different version, the weightField with a sampled surface should work more recent versions, such as OpenFOAM-v2106 or the upcoming OpenFOAM-v2112. They also support multiple weight fields - for example (rho U) to have mass-weighted.

Direct weighting with a surface field (phi) will only work for a small subset of sampled surfaces - faceZone, patch - where it is possible to reliably map their values to a corresponding sample surface face.

[EZS]

Thank you for your answer! I will check if I can move my project from OF6 to OFv2106.

[olesen]

Originally Posted by EZS

Thank you for your answer! I will check if I can move my project from OF6 to OFv2106.

Probably about a week or so until the December release (OpenFOAM-v2112).

[chc]

Were you able to create your zone to find the average mass flow using this method? If so do you mind sharing your process?

[EZS]

Unfortunately, I didn't have time to try it. I'm currently not working on any OpenFoam projects.