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dieselFoam: Summation of total droplet momentum in a Cell

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Old   July 17, 2010, 21:11
Default dieselFoam: Summation of total droplet momentum in a Cell
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Hello,

Can someone share their experience on how can total momentum of droplets in a cell be calculated and stored in a a variable. I am new to C++ language and I really need someone's experience in creating a new variables in dieselFoam.

Thanks,
Nir
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Old   July 17, 2010, 23:15
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Quote:
Originally Posted by N. A. View Post
Hello,

Can someone share their experience on how can total momentum of droplets in a cell be calculated and stored in a a variable. I am new to C++ language and I really need someone's experience in creating a new variables in dieselFoam.

Thanks,
Nir
You can do it like this

volVectorField moment
(
IOobject
(
"moment",
runTime.timeName(),
mesh,
IOobject::NO_READ,
IOobject::NO_WRITE
),
mesh,
dimensionedVector("moment", dimensionSet(1, -2, -2, 0, 0),vector::zero)
);

spray::iterator mol(dieselSpray.begin());

for (mol = dieselSpray.begin(); mol != dieselSpray.end(); ++mol)
{
label cellI=mol().cell();
moment[cellI]+=mol().m()*mol().U();
}

Junwei
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Old   July 17, 2010, 23:52
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Hi Junwei,

Thanks. Is this addition to be made in dieselFoam.C of the solver dieselFoam or should be added in one of the files in the ../src/dieselSpray.. directory.

Thanks,
Nir
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Old   July 18, 2010, 04:21
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Quote:
Originally Posted by N. A. View Post
Hi Junwei,

Thanks. Is this addition to be made in dieselFoam.C of the solver dieselFoam or should be added in one of the files in the ../src/dieselSpray.. directory.

Thanks,
Nir
I think you can do it in dieselFoam.

Junwei
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Old   August 26, 2010, 12:58
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Hi Junwei,

I wish to add a variable in the lagrangian equations and solve for it. Just as we solve for x,d, m, T, etc for particle properties, I am trying to solve for distorted surface area for each particle and wish to calculate each time-step.

Do you know how another variable be added into lagrangian variables and solve for it.

Any ifnormation will be very helpful.

Thanks,
Nir
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Old   August 26, 2010, 21:37
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Hi Nir
You can add a variable into parcel class in /src/lagrangian/dieselSpray/parcel/
1) add variable
2) add read and write access function to this variable
3) add IO operation in parcelIO.C

You can alter the variable like the following code
cloudObject is the particle cloud. yourVariable is your variable name you defined.
for
(
spray::iterator particle = cloudObject.begin();
particle != cloudObject.end();
++particle
)
{
particle().yourVariable()=.... // do as you like.
}

Regards, Junwei
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Old   September 14, 2010, 09:37
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What a nice topic!

Last edited by Palminchi; September 20, 2010 at 07:48.
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Old   September 20, 2010, 07:43
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Dear su_junwei,

As far as I understand, if you are multiplying m()*U(), the dimmension of the vector when you defined it before should be (1 1 -1), shouldn't it?
Please, confirm if this is something I don't understand or something I can't see when you make the iterator programming.

And other question is, with the iterator, could I obtain the momentum flux of the droplets(which is m*U^2) ? And do you know how I could obtain the gas momentum?

Best regards and thank you very much,
Palma.
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