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How to extract Cp values at inlet

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Old   August 8, 2006, 03:29
Default If I declare a variable like:
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Dihao Tang
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If I declare a variable like:

const fvPatchVectorField& Up =
lookupPatchField<volvectorfield,>("U");

I get Up value from inlet. But it seems like there is no such declaration for heat capacity Cp so that I can also obtain its values at inlet. My question is how I can get Cp values(inlet)? Thanks!
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Old   August 8, 2006, 07:59
Default Sorry, here the question chang
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Sorry, here the question changes. If I use janafThermo, the Cp is computed by a function about T. In the code of specieThermo.H, I found:

inline scalar Cp(const scalar T) const;

I guess this Cp is computed from T, right? So how do I access Cp(const scalar T)? Thanks!
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Old   August 8, 2006, 09:46
Default Here's how I figured it out.
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Fabian Peng Karrholm
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Here's how I figured it out.

Go to the solves directory, /OpenFOAM-1.3/applications/solvers

Surely, some of the solvers use Cp(T), so let's see if one does with this command:

grep Cp * -RI

Oh, it turns out, alot of them also use Cpu time, so lets remove those hits:

grep Cp * -RI | grep -v Cpu

Ahh, the solve dieselEngineFoam uses Cp (which sounds natural), so if you go to combustion/dieselEngineFoam/hEqn.H

you'll see an example of how it's used in the code. the chemistryModel chemistry is defined in createFields.H of the same solver.

/Fabian
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Old   August 9, 2006, 01:43
Default Thanks for your information. B
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Thanks for your information. By the way, I'm using sonicTurbFoam which doesn't have anything to do with combustion. Is there other possibility to get Cp(T)?

If dieselEngineFoam is helpful to my case, but I don't know how to import this chemistry stuff into my code due to my poor C++ knowledge. Could you advise me more, if I want to access Cp(T)? Thank you for your help!
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Old   August 9, 2006, 02:31
Default you have to instance an approp
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stefan
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you have to instance an appropiate (see http://foam.sourceforge.net/doc/Doxygen/html/d2/d3e/classFoam_1_1basicThermo.htm l#a16) 'thermo' object which has a member function 'Cp'

example:

autoPtr<hthermo> thermo
(
hThermo::New(mesh)
);

The class hThermo comes with the following member function:
tmp<scalarfield> Cp (const scalarField &T, const label patchi)

hth
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Old   August 9, 2006, 02:48
Default Thanks! I know what you meant
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Thanks! I know what you meant here. But this Cp is scalarField, I also tried this before, what I got is the Cp values at inlet. I want to use the scalar Cp which I think is defined in specieThermo.H:

inline scalar Cp(const scalar T) const;

Is there any way to get this Cp? Thanks again!
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Old   August 10, 2006, 02:35
Default I am aware of that this is a C
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Dihao Tang
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I am aware of that this is a C++ problem: given the class template, how to access its member? It is kind of hard for me to handle due to my poor C++ skill. Can somebody show me how to manage to do that? Thanks!
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Old   August 10, 2006, 08:41
Default I tried my way to define an ob
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I tried my way to define an object whose type is specieThermo<class>, that is what I did so far:

first include "specieThermo.H", and declare an object:
specieThermo<scalar> test(scalar);

I expected the object "test" has the member Cp(T). But it doesn't behave the way I hoped. The error message is:

error: request for member 'Cp' in 'Foam::test', which is of non-class type 'Foam::specieThermo<double> ()(Foam::scalar)'

Then I tried to output the object "test" to see what I can get. Then the warning showed up:

warning: the address of 'Foam::specieThermo<double> Foam::testing(Foam::scalar)', will always evaluate as 'true'

What does that mean? I think I did something wrong. So what mistake I did? Please give me some information. Thank you!
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Old   August 14, 2006, 03:17
Default I found that there is an examp
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Dihao Tang
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I found that there is an example about how to define thermo type in equilibriumFlameT.C, which is:

typedef specieThermo<janafthermo<perfectgas> > thermo;

I think that is the thermo type I need to input when I declare an object specieThermo<thermo> test(thermo); So I guess the next step would be declare a thermo object in order to access Cp(T) value. The format is in my opinion:

test(objectOfThermo).Cp(T);

Am I right? But I don't understand how to create this objectOfThermo and the mechanism behind this. I just guess objectOfThermo should be related to "thermophysicalProperties". I'm very eager to know if I am on the right way, please give some tips! Thanks!
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