Hi, i have modelled a thermal system in simscape: the unit includes a polymer casing inside which there is a heater, heat spreader and a fluid sample in that order. i wish to validate this model by hand calculations such as finding the time constant. However i do not know how to find the time constant of such a system. Any ideas/suggestions ? the individual elements covering the fluid sample are also masses that store heat. If i keep the heater input at zero and start the simulation keeping the fluid temperature at 100 C with all other componenets at 25 C then i get resulting temperature profile which asymptotically reaches 25 C. How can i be sure that such a model is correct ? Is there any other calculation verification possible ? thanks for the help.. and please let me know if u need further explanation of the unit. I really need to prove that my Simscape model is correct before i can move on.. thanks ..