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Using temperature to modify viscosity

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Old   July 19, 2022, 09:46
Exclamation Using temperature to modify viscosity
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Hi! I'm rather new to OpenFoam, and I'm trying to use temperature to define viscosity. What I'd like is for viscosity to remain "normal" (I'm using a polynomial model for it) while temperature is below a certain value. But when temperature is over it, I want the viscosity to be 100 or 1000 times higher so that it acts sort of as a solid particle.

I've tried multiple things I've seen in this forum with no success. I've created a modified polynomial transport file, but whatever I've done to try to modify it to do what I want, it complains when I compile.

The last thing I tried is:
template<class Thermo, int PolySize>
Foam:olynomialSplitTransport<Thermo, PolySize>:olynomialSplitTransport
(
const dictionary& dict
)
:
/* if (Thermo.T()).value() > 293) */
Thermo(dict),
{
if (T.field() > 293)
{
// temperature over soldification temperature
muCoeffs_
(
dict.subDict("transport").lookup
(
"muCoeffs<" + Foam::name(PolySize) + '>'
)
),
kappaCoeffs_
(
dict.subDict("transport").lookup
(
"kappaCoeffs<" + Foam::name(PolySize) + '>'
)
);
}
else
{
// solidification due to temperature below solidification temperature
// here i should change the definition of viscosity so it is 100 o 1000x higher
muCoeffs_
(
dict.subDict("transport").lookup
(
"muCoeffs<" + Foam::name(PolySize) + '>'
)
),
kappaCoeffs_
(
dict.subDict("transport").lookup
(
"kappaCoeffs<" + Foam::name(PolySize) + '>'
)
);
}
}

{}

But I get the following error when compiling:
In file included from lnInclude/polynomialSplitTransport.H:218,
from lnInclude/thermoPhysicsTypes.H:54,
from lnInclude/reactionTypes.H:35,
from reaction/reactions/makeReactions.C:26:
lnInclude/polynomialSplitTransport.C: In constructor ‘Foam:olynomialSplitTransport<Thermo, PolySize>:olynomialSplitTransport(const Foam::dictionary&)’:
lnInclude/polynomialSplitTransport.C:39:5: error: expected identifier before ‘{’ token
39 | {
| ^
lnInclude/polynomialSplitTransport.C:40:11: error: ‘T’ was not declared in this scope
40 | if (T.field() > 293)
| ^
lnInclude/polynomialSplitTransport.C: At global scope:
lnInclude/polynomialSplitTransport.C:78:1: error: expected unqualified-id before ‘{’ token
78 | {}
| ^
make: *** [/opt/openfoam7/wmake/rules/General/transform:26: Make/linux64GccDPInt32Opt/reaction/reactions/makeReactions.o] Error 1


I think if I'm able to "call" the temperature correctly it should work, but i dont know exactly how to call it as to use it in the condition of the if structure.
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