convert pointScalarField to volScalarField

saralen · December 4, 2017, 09:51

Hi All,

I'm new to OpenFOAM and I'm trying to convert a pointScalarField to a volScalarField. How can I do?

Thanks a lot for your help.
Sara

alexeym · December 4, 2017, 10:21

Hi,

You can iterate over volScalarField and use interpolatePointToCell function ( https://cpp.openfoam.org/v5/namespac...ec0038ef8cdd46).

saralen · December 4, 2017, 11:00

Thanks for your answer alexeym!
Sara

saralen · December 6, 2017, 09:58

Can I also ask you for a description of a volScalarField 's "structure" ?

About the interpolateToPointCell function, I found it requests the following input : geometric field and a label index, isn't it?
To convert the pointScalarField in a volScalarField I'm going to do a "for loop" on the label index....could it be correct?
Anyway I can't understand if I'm wrong because I can't find the structure of a volScalarField in the user guide...

Thanks

alexeym · December 6, 2017, 12:39

Yes, you can (and you actually did

).

If we oversimplify, volScalarField is a list of scalar values one for each cell of a mesh, pointScalarField is a list of scalar values, one for each point of the mesh (and both are specialisation of GeometricField type, see volFieldsFwd.H and pointFields.H).

So, yes, you iterate over volume field with for loop or forAll macro, and pass label index and point field into interpolatePointToCell function. Function looks up faces of the cell, then for each face it looks up vertices of the face, takes values at these points and returns average (see https://cpp.openfoam.org/v5/interpol...8C_source.html). You take returned value and assign it to cell with above mentioned index.

Yet, depending on the nature of your data, maybe you could select another weighting strategy (rather than number of vertices of a given cell).

December 4, 2017, 09:51	convert pointScalarField to volScalarField	#1
saralen New Member Sara Lenzi Join Date: Jun 2017 Location: Italy Posts: 8 Rep Power: 8	Hi All, I'm new to OpenFOAM and I'm trying to convert a pointScalarField to a volScalarField. How can I do? Thanks a lot for your help. Sara

December 4, 2017, 10:21		#2
alexeym Senior Member Alexey Matveichev Join Date: Aug 2011 Location: Nancy, France Posts: 1,930 Rep Power: 38	Hi, You can iterate over volScalarField and use interpolatePointToCell function ( https://cpp.openfoam.org/v5/namespac...ec0038ef8cdd46). saralen likes this.

December 6, 2017, 09:58		#4
saralen New Member Sara Lenzi Join Date: Jun 2017 Location: Italy Posts: 8 Rep Power: 8	Can I also ask you for a description of a volScalarField 's "structure" ? About the interpolateToPointCell function, I found it requests the following input : geometric field and a label index, isn't it? To convert the pointScalarField in a volScalarField I'm going to do a "for loop" on the label index....could it be correct? Anyway I can't understand if I'm wrong because I can't find the structure of a volScalarField in the user guide... Thanks Last edited by saralen; December 7, 2017 at 08:33.

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December 4, 2017, 11:00		#3
saralen New Member Sara Lenzi Join Date: Jun 2017 Location: Italy Posts: 8 Rep Power: 8	Thanks for your answer alexeym! Sara

December 6, 2017, 12:39		#5
alexeym Senior Member Alexey Matveichev Join Date: Aug 2011 Location: Nancy, France Posts: 1,930 Rep Power: 38	Yes, you can (and you actually did ). If we oversimplify, volScalarField is a list of scalar values one for each cell of a mesh, pointScalarField is a list of scalar values, one for each point of the mesh (and both are specialisation of GeometricField type, see volFieldsFwd.H and pointFields.H). So, yes, you iterate over volume field with for loop or forAll macro, and pass label index and point field into interpolatePointToCell function. Function looks up faces of the cell, then for each face it looks up vertices of the face, takes values at these points and returns average (see https://cpp.openfoam.org/v5/interpol...8C_source.html). You take returned value and assign it to cell with above mentioned index. Yet, depending on the nature of your data, maybe you could select another weighting strategy (rather than number of vertices of a given cell).