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Hi,

I´d like to solve a simple problem but I came across issues. My time dependent heat source isn´t simulated correctly.

I´m simulating a wall with two layers with different external temperatures on the different sufaces. On the colder surface I´m adding a heat source on the surface (~60 [W/m²]). This heat source should be active when the wall (~35 cm thick) is more or less in a steady state and from there a heating duration of 8 [h] is planned.

For the heat source I´ve tried different definitions:

if(t < 576000,0,if(t > 604800,0,60)) 60rect1 where rect1 is a rectangular window 60pw1 where pw1 is a piecewise function with the conditions

From To Value 0 576000 0 160 h 576000 604800 1 160 h - 168 h 604800 800000 0 168 h - end of the simulation

Sometimes the animation player shows, that my source is neglected. The problem is sometimes solved by changing the time step control from "free" to "intermediate" and using adaptive mesh control.

The problem with the simulation is that the heat flux in X-direction is way smaller than it should be on the surface as well as the time when the heat source is active doesn´t fit. In the attached graph the error is more easy to be seen.

I apprechiate all help and every tip that could lead to a solution.

Best regards

Sebastian