Following your last message, please see my answers below:
1. The material for both geometries is asphalt. They have different densities and therefore different thermal conductivity and specific heat capacities. Four values of thermal conductivities at four different temperatures are used for both geometries. These measurements are completed in the laboratory for the specific asphalt mixtures used in the model.
2. T1=20C is applied to the whole volume of geometry 1. I have changed however lately on how I apply T2. In my latest simulation model geometry 2 has different temperatures on all its external surfaces. On this way I have much better match with my experimental results. It was happened in reality. The mix had different temperatures on its surfaces. So T2 is applied now on faces.
What dies it mean to patch initial temperatures? Could you explain more. I do not think I am doing this and is maybe where the problem is.
3. Yes, I want to find change of temperature with respect to time. Is it wrong to use initially steady state? I use steady state to apply T1 and T2 and then run transient analysis.
4. Steps in total 17:
Step time: 1 has End time:1s
Step time: 2 has End time:10s
Step time: 3 has End time:20s
Step time: 4 has End time:40s
Step time: 5 has End time:60s
Step time: 6 has End time:80s
Step time: 7 has End time:100s
Step time: 8 has End time:150s
Step time: 9 has End time:200s
Step time: 10 has End time:250s
Step time: 11 has End time00s
Step time: 12 has End time50s
Step time: 13 has End time:400s
Step time: 14 has End time:420s
Step time: 15 has End time:440s
Step time: 16 has End time:460s
Step time: 17 has End time:480s
5. Convection and radiation is applied at the top surface of the geometry assembly shown in my last figure. Emissivity for radiation to ambient is equal to 0.967 with ambient temperature set at 21.5C as in the whole simulation model. Film coefficient value for convection is chosen from Ansys itself values (Stagnant Air - simplified Case).
Many thanks for your help. I hope the above helps to better understand how the model is built.