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Old   October 14, 2009, 09:17
Default Incompatible dimensions for operation
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Pramod
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Hi friends,
I tried to combine solvers settlingFoam and bubbleFoam, I could compile successfully, bu when I ran my solver, which gives error, which states,
incompatible dimensions for operation
[alpha[0 0 -1 0 0 0 0] ] + [alpha[1 -3 -1 0 0 0 0] ]#0 Foam::error:rintStack(Foam::Ostream&) in "/home/baburao/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::error::abort() in "/home/baburao/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 void Foam::checkMethod<double>(Foam::fvMatrix<double> const&, Foam::fvMatrix<double> const&, char const*) in "/home/baburao/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/comsol"
#3 Foam::tmp<Foam::fvMatrix<double> > Foam:perator+<double>(Foam::tmp<Foam::fvMatrix<d ouble> > const&, Foam::tmp<Foam::fvMatrix<double> > const&) in "/home/baburao/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/comsol"
#4 main in "/home/baburao/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/comsol"
#5 __libc_start_main in "/lib/libc.so.6"
#6 _start at /build/buildd/glibc-2.9/csu/../sysdeps/x86_64/elf/start.S:116


From function checkMethod(const fvMatrix<Type>&, const fvMatrix<Type>&)
in file /home/baburao/OpenFOAM/OpenFOAM-1.5/src/finiteVolume/lnInclude/fvMatrix.C at line 1184.

FOAM aborting


Can anyone help with this errorsince I am very new to OpenFoam and C++,

Thanks in advance,

Anticipating for your kind reply,

Pramod
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Old   October 14, 2009, 09:25
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Sachin Kanetkar
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I guess there is problem with "rho" could u write the alphaEqn

Sachin
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Old   October 14, 2009, 10:06
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alphaEqn has been attached,

Thanks for your response Sachin

Pramod
Attached Files
File Type: h alphaEqn.H (1.2 KB, 81 views)
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Old   October 14, 2009, 11:43
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Laurence R. McGlashan
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You're obviously using the compressible formulation of 'phi', which includes the density, and that's why you have a dimensions mismatch.
Before 'sticking' codes together, make sure you know exactly what equations you are solving for. If you look at the difference between the alphaEqn in settlingFoam and bubbleFoam the reason it isn't working should be obvious.
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Old   October 14, 2009, 11:54
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yes , as I mentioned since I dont know C++ upto the mark , I tried to stick with the solvers. Sorry to tell this, can anyone help me regarding this,

Thanks in advance,
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Old   October 14, 2009, 12:02
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Laurence R. McGlashan
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This doesn't have anything to do with C++. I am assuming that you are solving:

fvm::ddt(alpha) + fvm::div(phi,alpha) + whatever

The problem you have is that your dimensions are different. alpha is dimensionless so the first term will have a dimension of s^{-1}. The second term has phi, which has dimensions of m^3 s^{-1}, and alpha which is dimensionless, so that term should also have dimensions of s^{-1}.

You are calculating phi using something akin to rho*U, which means your phi has different dimensions to the phi in the equation above.

Is your case compressible/incompressible?
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Old   October 14, 2009, 13:44
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Alberto Passalacqua
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In bubbleFoam the flux is volumetric:

phia = fvc::interpolate(Ua) & mesh.Sf();

in settlingFoam phi is created with compressibeCreatePhi.H in createFields.H

What is the purpose of combining these two codes?
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Old   October 15, 2009, 04:24
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Quote:
Originally Posted by l_r_mcglashan View Post
This doesn't have anything to do with C++. I am assuming that you are solving:

fvm::ddt(alpha) + fvm::div(phi,alpha) + whatever

The problem you have is that your dimensions are different. alpha is dimensionless so the first term will have a dimension of s^{-1}. The second term has phi, which has dimensions of m^3 s^{-1}, and alpha which is dimensionless, so that term should also have dimensions of s^{-1}.

You are calculating phi using something akin to rho*U, which means your phi has different dimensions to the phi in the equation above.

Is your case compressible/incompressible?
Firstly thank you very much for your patient response Laurence, its helping me

I am solving with incompressible fluids,
I am open for any suggesstion

Thank you
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Old   October 15, 2009, 05:00
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Quote:
Originally Posted by alberto View Post
In bubbleFoam the flux is volumetric:

phia = fvc::interpolate(Ua) & mesh.Sf();

in settlingFoam phi is created with compressibeCreatePhi.H in createFields.H

What is the purpose of combining these two codes?
Thanks alberto for your response, I am trying to combine the codes since my case has both setlingFoam n bubbleFoam involved,

Any suggestions are welcome,
Thank you
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