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Time-dependent problem: noisy temperature boundary condition. Is it possible to change the noise magnitude in a sweep analysis?

Posted Feb 26, 2024, 9:26 a.m. EST Heat Transfer, Modeling Tools & Definitions 1 Reply

Maja Danovska
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Hello people,

Is it possible to sum to a triangular temperature profile, defined as a piecewise linear function in the range from zero to 6000 minutes, a random signal (describing a sort of noise) with a variable magnitude that maybe I can change in a sweep analysis? I tried everything but there is no possibility to generate a random signal in exactly the same period of the temperature profile.

What would you suggest to do?

Thanks in advance.

1 Reply Last Post Feb 26, 2024, 4:32 p.m. EST
Edgar J. Kaiser Certified Consultant
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Posted: 8 months ago Feb 26, 2024, 4:32 p.m. EST

Maja,

a noise signal is not periodic by its nature. In case you want to see which way a disturbance on the triangular ramp affects the model, you might try to superimpose some function that behaves less pathologic for a time dependent solver than noise. You might start with a superimposed sine wave and adjust the solver for it. Once it works you may modify the sine to make it more noise-like, e.g. by superimposing amplitude and frequency modulation to it. In any case you must choose a time stepping that resolves the superimposed function properly.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Maja, a noise signal is not periodic by its nature. In case you want to see which way a disturbance on the triangular ramp affects the model, you might try to superimpose some function that behaves less pathologic for a time dependent solver than noise. You might start with a superimposed sine wave and adjust the solver for it. Once it works you may modify the sine to make it more noise-like, e.g. by superimposing amplitude and frequency modulation to it. In any case you must choose a time stepping that resolves the superimposed function properly. Cheers Edgar

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