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-   -   How to probe all points on a patch? (http://www.cfd-online.com/Forums/openfoam-solving/91940-how-probe-all-points-patch.html)

strikeraj August 26, 2011 23:28

How to probe all points on a patch?
 
Hi

I am trying to run a transient flow over 3D airfoil case and I would like to record the surface pressure on the airfoil for the whole computation time frame.

However, it seems that it expects only vectors within probeLocations. Is there any way to have it probe all the points on the surface of a patch?

I tried

Code:

probeLocations
(
patches
(
WALL
)
);

but it does not work

any ideas??

Thanks a lot

gschaider August 27, 2011 10:40

Quote:

Originally Posted by strikeraj (Post 321852)
Hi

I am trying to run a transient flow over 3D airfoil case and I would like to record the surface pressure on the airfoil for the whole computation time frame.

However, it seems that it expects only vectors within probeLocations. Is there any way to have it probe all the points on the surface of a patch?

I tried

Code:

probeLocations
(
patches
(
WALL
)
);

but it does not work

any ideas??

Thanks a lot

What you want is a sampledSurface (type: patch). Have a look at the example dictionary that comes with the sample utility. There is also a functionObject that comes with OF that uses that mechanism

strikeraj September 18, 2011 22:06

Quote:

Originally Posted by gschaider (Post 321910)
What you want is a sampledSurface (type: patch). Have a look at the example dictionary that comes with the sample utility. There is also a functionObject that comes with OF that uses that mechanism

Hi

Thanks for your reply. But just I found out that the sample utility is for post-processing only. I am wishing to write out the pressure on a boundary surface for every time step without the need to write all variables for all time steps.
Is there an utility that can do this?

Thanks,
Tom

gschaider September 19, 2011 05:28

Quote:

Originally Posted by strikeraj (Post 324598)
Hi

Thanks for your reply. But just I found out that the sample utility is for post-processing only. I am wishing to write out the pressure on a boundary surface for every time step without the need to write all variables for all time steps.
Is there an utility that can do this?

Thanks,
Tom

All the functionality of the sample utility exists in two functionObjects. "set" and "surface" are the names, I think

strikeraj September 19, 2011 08:13

Quote:

Originally Posted by gschaider (Post 324629)
All the functionality of the sample utility exists in two functionObjects. "set" and "surface" are the names, I think

Hi

Thank you for you reply. I manage to get sample utility to work, just it does not work the way I thought it would.

I have a transient simulation for lets say 100k time steps. I cannot afford to save all the data for every single one. I am probably writing for every 1000 time steps. However, I need the surface pressure data for every time step on the wall boundary. I tried probing but it does not work with patch and sample utility is only a post-processing tool to extract surface data from the complete result.

Thanks,
Tom

gschaider September 19, 2011 10:45

Quote:

Originally Posted by strikeraj (Post 324654)
Hi

Thank you for you reply. I manage to get sample utility to work, just it does not work the way I thought it would.

I have a transient simulation for lets say 100k time steps. I cannot afford to save all the data for every single one. I am probably writing for every 1000 time steps. However, I need the surface pressure data for every time step on the wall boundary. I tried probing but it does not work with patch and sample utility is only a post-processing tool to extract surface data from the complete result.

Thanks,
Tom

The functionObjects do exactly what you want: sample the data during the run (without extra data hitting the disk)

strikeraj September 20, 2011 09:54

Quote:

Originally Posted by gschaider (Post 324682)
The functionObjects do exactly what you want: sample the data during the run (without extra data hitting the disk)

Hi

Thank you for your reply. I tried searching a bit but failed to find out exactly how functionObjects work. Do you know which tutorial uses it or where I can find an explanation on how to set it up? Is it compatible with 2.0.1?

Thanks,
Tom

gschaider September 20, 2011 12:51

Quote:

Originally Posted by strikeraj (Post 324859)
Hi

Thank you for your reply. I tried searching a bit but failed to find out exactly how functionObjects work. Do you know which tutorial uses it or where I can find an explanation on how to set it up? Is it compatible with 2.0.1?

Thanks,
Tom

Have a look at the sloshingTank2D-tutorial. The controlDict

strikeraj September 20, 2011 16:53

Quote:

Originally Posted by gschaider (Post 324899)
Have a look at the sloshingTank2D-tutorial. The controlDict

Thank you so much for your help sir. That works like a charm.

sandy April 10, 2012 02:48

Who know what is the different use between the probe and sample?

amin144 April 24, 2012 14:45

Quote:

Originally Posted by sandy (Post 353876)
Who know what is the different use between the probe and sample?

Sample write data which you want in a special location that you marked
sample write data of each step in a folder

if you have transient case, you need data in a special location during time
probe give you a file which contain data of a locations during all time steps ( you have one file for ecah point contain all time steps in probe , not many files for each time step like sample )


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