initialize pressure gradient

jiejie · June 30, 2011, 08:55

Dear Foamers

I am try to setup a Gaussian vortex case, which has a given velocity field and pressure gradient field. I am able to write a app to initialize the velocity across the flow domain by looping through each individual cells. However, I am having problem to initialize the pressure gradient as it requires more than one cell. Would anyone have some suggestions on how to implement this?

Thank you.

nimasam · June 30, 2011, 10:25

my suggestion :
1) add to createFields.H
volVectorField dpdx
(
IOobject
(
"dpdx",
runTime.timeName(),
mesh,
IOobject::MUST_READ,
IOobject::AUTO_WRITE
),
mesh
);

2) add file dpdx with dimension of (p/length) in folder 0

3) use funkySetFields from openFoam wiki to initialize the field

jiejie · June 30, 2011, 10:36

Hi nimasam

It requires more cell points to calculate the pressure gradient but not sure how to convert pressure gradient to pressure?

I came across the funkyFields but never used it before. Would you be able to elaborate a bit more on it?

Thanks for the reply.

nimasam · June 30, 2011, 10:46

i can't understand, whats ur mean ?

jiejie · June 30, 2011, 10:49

Quote:

Originally Posted by nimasam

i can't understand, whats ur mean ?

Sorry for the confusion. What I mean is you need more than one cell to calculate the pressure gradient. Is it possible to calculate the pressure at each cell if I know the pressure gradient? This is because I need to initialize the pressure field but I only have the information of the pressure gradient.

nimasam · June 30, 2011, 10:59

im not sure! it would be compilicated but maybe you can look at streamFunction and use similar method!

June 30, 2011, 08:55	initialize pressure gradient	#1
jiejie Senior Member Jie Join Date: Jan 2010 Location: Australia Posts: 134 Rep Power: 16	Dear Foamers I am try to setup a Gaussian vortex case, which has a given velocity field and pressure gradient field. I am able to write a app to initialize the velocity across the flow domain by looping through each individual cells. However, I am having problem to initialize the pressure gradient as it requires more than one cell. Would anyone have some suggestions on how to implement this? Thank you.

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June 30, 2011, 10:25		#2
nimasam Senior Member Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,267 Blog Entries: 1 Rep Power: 25	my suggestion : 1) add to createFields.H volVectorField dpdx ( IOobject ( "dpdx", runTime.timeName(), mesh, IOobject::MUST_READ, IOobject::AUTO_WRITE ), mesh ); 2) add file dpdx with dimension of (p/length) in folder 0 3) use funkySetFields from openFoam wiki to initialize the field

June 30, 2011, 10:36		#3
jiejie Senior Member Jie Join Date: Jan 2010 Location: Australia Posts: 134 Rep Power: 16	Hi nimasam It requires more cell points to calculate the pressure gradient but not sure how to convert pressure gradient to pressure? I came across the funkyFields but never used it before. Would you be able to elaborate a bit more on it? Thanks for the reply.

June 30, 2011, 10:46		#4
nimasam Senior Member Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,267 Blog Entries: 1 Rep Power: 25	i can't understand, whats ur mean ?

June 30, 2011, 10:59		#6
nimasam Senior Member Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,267 Blog Entries: 1 Rep Power: 25	im not sure! it would be compilicated but maybe you can look at streamFunction and use similar method!