[iggor]

Hi everybody,
I'm a new OF user and i face some problem with thermophysical properties modification. Let me expose the context : i'd like to run a compressible solver in a channel (perfect gas, sutherland transport etc.) and, for some reasons, i'd like to check it with a liquid (water) wich is in fact really weakly compressible. It seems that OF has some internal database for thermophysical properties so i wonder if there is a way to modify only the thermophysicalproperties file which, for the moment, is implemented with air (as you could find it in the tuto 'rhoPorouSimplefoam') and replace it by water which should have intrinsic properties for an incompressible behavior but resolve with a compressible solver ?
Hope this is clear,
Thanks for you help,

[iggor]

I thought it was quite easy, maybe not it seems ...
Ideas are welcome !
Have a nice WE !!

[wizard1301]

You have to edit the constant/thermophysicalProperties file in your case dir with the themophysical properties of water.

[iggor]

Thanks,
My problem is that i haven't found the syntaxe defining water propoerties in the constant/thermophysicalProperties file while it is well explained for gaseous component in the documentation (and there is also a lot of exemples in tuto).

[wizard1301]

Sorry, probably I didn't understand, what do you mean for water?
You say you want to solve with a standard compressible gas solver (perfect gas, etc..). Right? You have to set Reynolds Mach Prandtl numbers for your simulation to describe a flow of water in certain geometry.

[iggor]

To clarify :
- Considering for example the tuto rhoporousSimplefoam, it treats with air (gas) and a compressible solver. All I want to do is to compute it with liquid (water) instead of air with exactly the same compressible solver.

- I tought it was possible to modify it into the constant/thermophysicalProperties file but I haven't found the syntaxe for defining water.

- Is there a database for liquids in OpenFoam (it seems but very few doc about it) and how refer to it in the constant/thermophysicalProperties ?

- I know the physic of my problem but I cannot translate it into OpenFoam language, it is quite frustating !!

Thanx for your help,

[wizard1301]

Another question to clarify
Do you want to treat liquid water as a perfect gas, right?
In that case you have to specify in the thermoPhysical file
the property of water (cp, gas costant, ...)
Take a look at
http://www.opencfd.co.uk/openfoam/do...calModels.html


Antonio

[Davoche]

In fact, the Perfect gas hypothesis is not applicable, it calculates the density according to the pressure and temperature variation. It will not bypass the compressible behavior of your 'fluid'

[iggor]

Yes, indeed ...
My idea is to use the H2O.H liquid water properties instead of thermoType<blabla><PerfectGas> in the thermoPhysical file should be able to link rho with (p,T).
But, when i set this in this file :

liquidComponents
(
H2O
);
liquidProperties
{
H2O H2O defaultCoeffs;
};

Then, Openfoam returns me an error 'Thermotype undefined'. So thermoType, wich seems to be for gas definition only seems to be mandatory for using the constant/thermophysicalProperties files. A little bit confuse now ...

[chiven]

hi, iggor, how about the progress of thermophysicalproperties file of water? I also meet this problem. Would you please post your experience about it? thanks.

[schmidt_d]

Along a different line of thinking, have you looked at sonicLiquidFoam? It assumes a linear variation of pressure and density, with a constant compressibility. The only tricky part is I think the derivation assumes spatially constant phi.
-David

[chiven]

Dear David,
Thank you for the comments. sonicLiquidFoam only deals with the liquid as Barotropic fluid, in which the pressure and density are supposed to satisfy a linear relation. It doesn't consider the thermophiscial model of the liquid. I am not sure its suitability for my case which is shown in "http://www.cfd-online.com/Forums/ope...oyantfoam.html."
Anyway, it is a very good suggestion.

[chiven]

Sorry, I make a mistake.

[az1362f]

hi

I want to use a diesel fuel with density of 840 kg/m3 and nitrogen (N2) as a chamber gas.
how can I set this two parameters?
I checked C7H16 files (.C & .H) but I don't know some parameters,for example rho_(61.38396836, 0.26211, 540.2, 0.28141),I checked html document but it does not describe these parameters:

NSRDSfunc5 (scalar a, scalar b, scalar c, scalar d)

any body can describe them and say how can I get the description of another input parameters like
pv_(87.829, -6996.4, -9.8802, 7.2099e-06, 2),
hl_(540.20, 499121.791545248, 0.38795, 0, 0, 0),
cp_(540.20, 6.11976102401216, 3137.69909384855, 182.274175063868, -254.530511150515),etc.

can I set chamber gas by changing N2 and O2 files in 0 directory in dieselfoam tutorial directory?
how can I describe a chamber gas with a defined properties like density viscosity,etc?

please help me
regard

[chiven]

Hi, John, please see this thread:

http://www.cfd-online.com/Forums/ope...-openfoam.html

good luck.

Chiven

[LarsPT]

Dear all,

I think my problem is exactly what is discussed in here. I want to simulate Rayleigh-Benard convection of silicon oil in a cubic cavity in order to compare it to experimental data.

Did anyone found a solution to replace air by silicon oil or even any other fluid? I searched the forum for hours but
did not find an proper solution.

A work around might be to use the air as fluid an scale the cavity and temperature differences to reach similar
values for the Ra number. But I am not sure whether it is completely similar.
Thanks in advance!
Lars