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Hello everyone,

I have a time-dependent problem in which there is a wall with a uniform temperature at time zero equl to 16 °C, after that, I apply a temperature pulse following a triangular temperature profile at one side, while the opposite side is kept at a constant temperature (equal to 16 °C). The triangular profile is defined with a piecewise linear function in the Definition section. The aim is to determine the heat flux (expressed in W/m2) at the opposite side of the solicitation. Usually, I get a solution in which the heat flux at the opposite side is zero at the beginning, then it follows a function approximately as e^(-ln(t^2)). The solver I am adopting is the Runge-Kutta one. Absolute tolerance is equal to 10^-5 and relative tolerance 10^-4.

So far there is no problem. I always get a solution. However, when I change temperature profile, that is, no more piecewise function but a function with a noise, I do not get any solution anymore. Instead of having a heat flux following e^(-ln(t^2)) I get weird trends.

Is there anyone that can help me? Should I configure the solver in a aspecific way since the boundary conditions is noisy?

I attach the COMSOL file at the external .txt file with the noisy triangular profile of the temperature.

Thanks for the help.