A question about KAPPA example

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1

Dear Users,

According to the available KAPPA example for calculating thermal conductivity using heat flux, at the end part of the code there are these lines:

variable scale equal $sdt/$t/t/vol variable k11 equal trap(f_JJ[3])*{scale}
variable k22 equal trap(f_JJ[4]){scale} variable k33 equal trap(f_JJ[5])*{scale}

my question is, when we are trying to calculate the “scale” variable, why we divide it by volume instead of multiplying it to volume? According to Geen-Kubo formula, we should multiply it to volume.

Sincerely,
Ali Y.Nobakht

in.heatflux (1.77 KB)

2

Question been asked before. look in the archives at:
http://lammps.sandia.gov/threads/msg35477.html

Carlos

3

Thank you for your response, but the “1/Volume” term is considered once in these lines:

variable Jx equal c_flux[1]/vol
variable Jy equal c_flux[2]/vol
variable Jz equal c_flux[3]/vol

if I am wrong, could you please provide some explanation for this?

Best Regards,
Ali

4

Question been asked before. look in the archives at:
http://lammps.sandia.gov/threads/msg35477.html

Sounds like deja-vu? That’s because you either did not READ the whole thread or you did not THINK about its meaning. You have a problem with a V showing in the numerator in the GK but not in the lammps script (denominator instead). But the GK assumes a flux J that includes the 1/V within (lammps does not include such a term in the calculation) and the flux appears quadratic in the GK formula. Now V*(1/V)^2 = 1/V and 2+2=4 and water boils at 100C at ambient conditions and …
Carlos