Discussion Forum

Hallo everyone,
in order to calculate the thermal conductivity and heat capacity i need to calculate the crystallization rate first:
Cp(a,T)=a*Cp_melt(T)+(1-a)*Cp_solid (the thermal conductivity is calculated equivalent)
Cp=thermal conductivity; a=crystallization rate; T=Temperature

Therefore alpha (=crystallization rate) can be calculated as time differential form with the following equation:
da/dt=K(T)*G(alpha)

Now there are two additional boundaries:
1) Due to an itterative melting and cooling process the material is locally molten several times. Meanes that the cristallization rate alpha needs to be set to zero if the current Temperature T hits the melting Temperature (T>T_melt).
2) Additionally the material can only start to crystallize if it has been molten in the process history. Means only if the TempHistory>T_melt the equation must be activated

So i tried to set up an ODE node in my model which should calculate alpha for the mentioned boundaries. The MaxTemperature (tracked through the Temperatur history) is also calculate in a seperate ODE and will be used in the ODE to set one boundary condition in the alpha ODE:

if(TempHistory>T_melt&&T<T_melt,d(da,t)-nojac(K(T)*G(alpha),da-nojac(0)
if(da<T_melt,alpha-nojac(alpha),alpha-nojac(0))

--->TempHistory=max Temp over the history; da=differential value alpha per timestep; T_melt=melting-Temperatur

For a better understanding i attached a screenshot.
Now i have been searching for my mistake for one week now. I would be happy about any hints, ideas why this doesn't work! am i doing something wrong?

regards
Florian