English expression - not stacionary heat flux

[lesy1]

Hi,
I am doing an experiment. I am heating a sample and changing a temperature on one surface of the sample as a sine function of time. Measuring heat flux I am trying to predict heat response of the sample. After some sine cycles heat response is in every next sine cycle the same. How do you call such response? (If it had constant values it would be stationary, but in this case values repeat with periode 2*pi).
Regards

 

[RoyalCat]

You would say that the system has reached a steady state, in which it has a response periodic in time.

In physics, saying that a system has reached its steady state, means that you've given it enough time to settle down and for any transient responses to die out. If you drive the system with some input signal, it will eventually conform to follow that signal somewhat.

You'll see the term used extensively in the study of harmonic oscillators and electric circuits, though the steady state responses there become much more complicated then simply following the input signal. :)