Average values on Boundary Conditions

helloworld11 · February 23, 2012, 12:21

Hi everyone,
I am quite new to OpenFoam world and I need some help. I would like to calculate average values of velocity and pressure on my boundary patches. Any idea how can I do it? Any help will be appreciated

bigphil · February 23, 2012, 13:00

Hi,

You could use the patchAverage and/or the patchIntegrate post processing OpenFOAM utilities.

For example, to calculate the average pressure on a patch called myInlet:

Code:

patchAverage p myInlet

Philip

helloworld11 · February 23, 2012, 13:09

Hello Philip,
Thank your for your answer. I just tied patchAverage p inlet for my case works fine.
But for the velocity values if type patchAverage U inlet, I get the error :

Only possible to average volScalarFields

Is there any way to over come that error?

bigphil · February 23, 2012, 13:16

helloworld11,

patchIntegrate and patchAverage only operate on volScalarFields, so if you decompose your velocity field into its components first using foamCalc, i.e.

Code:

foamCalc components U

Then you can run patchAverage on each component:

Code:

patchAverage Ux myInlet

You can also use foamCalc to do other things like calculate the magnitude of a volVectorField:

Code:

foamCalc mag U

If you type something like "foamCalc banana" it will give you all the options.

Philip

helloworld11 · February 23, 2012, 13:24

Philip,

I followed the instructions you gave and now I am able to get values. Thank you very much.

Vishsel · November 19, 2019, 01:12

Hi all,

Again i am initiating this old thread to find the average field values of two or three patches ..

Any command to measure the field average values of totally three patches ??

like three patches namely - inlet1,inlet2,inlet3 .. I need average value for three patches ..

Thanks in advance,
Vishsel

lumasci · March 22, 2023, 12:13

Quote:

Originally Posted by bigphil

Hi,

You could use the patchAverage and/or the patchIntegrate post processing OpenFOAM utilities.

For example, to calculate the average pressure on a patch called myInlet:

Code:

patchAverage p myInlet

Philip

Hi, how do you setup myInlet in 0/U or 0/p?
In my case, I want to create an 'artificial' patch in order to get a mapping of the velocity for this specific area.

Usually, I use paraview/cross section to achieve that, but in this case, the geometry is much more complex. Therefore, I want the value of the velocity in this patch.

February 23, 2012, 12:21	Average values on Boundary Conditions	#1
helloworld11 New Member Join Date: Feb 2012 Posts: 5 Rep Power: 14	Hi everyone, I am quite new to OpenFoam world and I need some help. I would like to calculate average values of velocity and pressure on my boundary patches. Any idea how can I do it? Any help will be appreciated

February 23, 2012, 13:00		#2
bigphil Super Moderator Philip Cardiff Join Date: Mar 2009 Location: Dublin, Ireland Posts: 1,097 Rep Power: 34	Hi, You could use the patchAverage and/or the patchIntegrate post processing OpenFOAM utilities. For example, to calculate the average pressure on a patch called myInlet: Code: patchAverage p myInlet Philip A CFD free user, Hamoon, lumasci and 1 others like this.

February 23, 2012, 13:16		#4
bigphil Super Moderator Philip Cardiff Join Date: Mar 2009 Location: Dublin, Ireland Posts: 1,097 Rep Power: 34	helloworld11, patchIntegrate and patchAverage only operate on volScalarFields, so if you decompose your velocity field into its components first using foamCalc, i.e. Code: foamCalc components U Then you can run patchAverage on each component: Code: patchAverage Ux myInlet You can also use foamCalc to do other things like calculate the magnitude of a volVectorField: Code: foamCalc mag U If you type something like "foamCalc banana" it will give you all the options. Philip reverseila likes this.

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February 23, 2012, 13:09		#3
helloworld11 New Member Join Date: Feb 2012 Posts: 5 Rep Power: 14	Hello Philip, Thank your for your answer. I just tied patchAverage p inlet for my case works fine. But for the velocity values if type patchAverage U inlet, I get the error : Only possible to average volScalarFields Is there any way to over come that error?

February 23, 2012, 13:24		#5
helloworld11 New Member Join Date: Feb 2012 Posts: 5 Rep Power: 14	Philip, I followed the instructions you gave and now I am able to get values. Thank you very much.

November 19, 2019, 01:12		#6
Vishsel Member Vishnu Join Date: May 2019 Location: Tamilnadu, India Posts: 55 Rep Power: 7	Hi all, Again i am initiating this old thread to find the average field values of two or three patches .. Any command to measure the field average values of totally three patches ?? like three patches namely - inlet1,inlet2,inlet3 .. I need average value for three patches .. Thanks in advance, Vishsel