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How to access to field point data

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Old   August 9, 2012, 10:40
Default How to access to field point data
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Jian Zhong
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Dear foamers,

I can have access to coordinate of point by:
mesh.points(), and field cell data by U.mesh().C()[].

But now my problem is that how to access and change the corresponding field point data if I choose some interested coordinate?

Many thanks,
Jian
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Old   August 10, 2012, 14:25
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Arne Stahlmann
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The values are always stored "in the cells" or at the boundaries, i.e. there is no value assignment for points. These only give the coordinates of the cells.

If you are interested in manipulating the (cell) values at a location x,y,z of interest, you could e.g. have a look at mesh.findCell(), Extracting cell index from x y z coordinates , which gives you the position in the field (cell index) you want to manipulate.

Greetings,
Arne
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Old   August 11, 2012, 06:35
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Quote:
Originally Posted by Arnoldinho View Post
The values are always stored "in the cells" or at the boundaries, i.e. there is no value assignment for points. These only give the coordinates of the cells.

If you are interested in manipulating the (cell) values at a location x,y,z of interest, you could e.g. have a look at mesh.findCell(), Extracting cell index from x y z coordinates , which gives you the position in the field (cell index) you want to manipulate.

Greetings,
Arne
Dear Arne,

Many thanks. After I have changed the field data of some cells (first layer of inlet as zero), the case can not run in parallel. Do you know how to solve the problem?

My best regards,
Jian
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Old   August 11, 2012, 07:11
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Arne Stahlmann
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You did not give the entire error you get from your run, so I'm not sure what's the problem.
But you have to keep in mind that if running in parallel, every single processor builds up its own mesh, i.e. face and point labels refer to the single processor meshes and are different from the global mesh labels!

Arne
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Old   August 11, 2012, 16:47
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Jian Zhong
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Quote:
Originally Posted by Arnoldinho View Post
You did not give the entire error you get from your run, so I'm not sure what's the problem.
But you have to keep in mind that if running in parallel, every single processor builds up its own mesh, i.e. face and point labels refer to the single processor meshes and are different from the global mesh labels!

Arne
Dear Arne,

Actually, I first select the first layer cell IDs near the inlet and outlet after searching the whole cells. Then I modified the corresponding cell values. It can run directly in one cpu, but can not run in parallel. Do you have any code or documents about parallel running?

My best regards,
Jian
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Old   August 14, 2012, 03:32
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Arne Stahlmann
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Hi Jian,

I am still not sure what the problem is. Did you check whether you modified the right cells, e.g. by having a look at the specific processorX folders in ParaView and giving the cells e.g. large numbers?
I am afraid I have no further documents about parallel coding, but my field/cell modifications so far work in parallel with no problem.
One hint: if you are just modifying the boundary-next cells, you could use
Code:
const label patchi = mesh.boundaryMesh().findPatchID("inlet");
U.boundaryField()[patchi] == whatever you want
which saves you the time-consuming searching for single cells.

Greetings,
Arne
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Old   May 21, 2015, 05:35
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Fei Fan
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Quote:
Originally Posted by Arnoldinho View Post
Hi Jian,

I am still not sure what the problem is. Did you check whether you modified the right cells, e.g. by having a look at the specific processorX folders in ParaView and giving the cells e.g. large numbers?
I am afraid I have no further documents about parallel coding, but my field/cell modifications so far work in parallel with no problem.
One hint: if you are just modifying the boundary-next cells, you could use
Code:
const label patchi = mesh.boundaryMesh().findPatchID("inlet");
U.boundaryField()[patchi] == whatever you want
which saves you the time-consuming searching for single cells.

Greetings,
Arne
Hi Arnoldinho:
I'm so sorry to trobule you and dig that old topic. I have a problem to access the points coorinadte of the assign face. for example i want to get the nodes coordinate of mesh.BoundaryField()[patchID][I], how i can do that? Thank you.
Greeting
Fan Fei
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