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Heat generation in concrete

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Hi,

I am trying to model the heat generation in a concrete piece. To do so I have used the Heat Transfer model in COMSOL 4.1 and the Heat Source to input the heat generation as a general source.

The function I use to describe the heat generation is function of the chemical affinity (aff), which in turn is a function of the hydration degree evolution in time (xi(t)), of the form:

q = L * aff(xi) * exp(-Ea/RT);
aff(xi) = a * xi(t)^b * (1-xi(t))^c;
xi(t) = 1/m * (t-0.01);

where L, a, b, c, Ea/RT and m are constants

I have tried to describe both xi(t) and aff(xi) trough analytical functions in the "global definitions" section but when I call xi(t) while defyning aff(xi) it does not work.

I have also tried to only define xi(t) as an analytical function and then directly describe the aff(xi) in the Heat Source model, but I do not know if this is well done because the results are not good and it says that the unities are wrong.

Maybe I am doing something wrong and maybe there is an easier way to do this...
If anyone could help me I would be very greatfull.

Thank you and have a nice evening,

Ana Gaspar

0 Replies Last Post 11 mag 2011, 09:54 GMT-4
COMSOL Moderator

Hello Ana Gaspar

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