[sabago]

Dear all!
I am new to OpenFOAM and I am trying to calculate a variable called vdrop = prefb*Hum+prefc (in vdrop.H) where prefb and prefc are constants defined in the constant folder and Hum is the concentration of the Humidity defined in diffusion. H as fvScalarMatrix HumEqn
(
(fvm::ddt(Hum)) == (fvm::laplacian(DH2Oeff, Hum))
);
HumEqn.solve();
where DH2Oeff is the effective diffusivity of water. The diffusion.H file runs fine but I get the following error when I turn on the vdrop.H. Any help will be much appreciated.

SANDRA

*Error starts here*
FOAM FATAL ERROR:
different mesh for fields vdrop and ((prefb*Hum)+prefc) during operatrion =

From function checkField(gf1, gf2, op)
in file /home/sandra/OpenFOAM/OpenFOAM-2.3.0/src/OpenFOAM/lnInclude/GeometricField.C at line 1122.

FOAM aborting

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::error::abort() at ??:?
#2
at ??:?
#3
at ??:?
#4 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#5
at ??:?
Aborted (core dumped)