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Sinusoidal Boundary Temperature Condition

Posted 10 mar 2023, 17:40 GMT-5 Heat Transfer 5 Replies

Sarah Chen
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Hi, I'm trying to specify a time dependent sinusoidal temperature boundary condition. I've defined a function in the screenshot attached. However, when I run a time dependent solver, the temperature of the boundary I've defined comes out looking jagged and not steady as seen in the second screenshot. How do I fix this issue?

5 Replies Last Post 14 mar 2023, 02:59 GMT-4
Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago 11 mar 2023, 03:18 GMT-5

Sarah,

you probably need to adjust the time stepping. For periodic signals you should set manual time steps that resolve the waveform. The automatic time stepping ignores the periodicity of the waveform. This is about the time steps in the solver, not the time steps you set in the study step.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Sarah, you probably need to adjust the time stepping. For periodic signals you should set manual time steps that resolve the waveform. The automatic time stepping ignores the periodicity of the waveform. This is about the time steps in the solver, not the time steps you set in the study step. Cheers Edgar
Sarah Chen
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Posted: 3 years ago 13 mar 2023, 17:48 GMT-4

Hi Edgar, How do you set manual time steps? I've tried both of these (attached) in the time solver. Thanks, Sarah

Hi Edgar, How do you set manual time steps? I've tried both of these (attached) in the time solver. Thanks, Sarah

Attachments:

Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago 13 mar 2023, 18:22 GMT-4

Those are the settings in the study step.

You need to change the time stepping in the solver. That is in Solver Configurations -> Time Dependent Solver -> Time Stepping

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Those are the settings in the study step. You need to change the time stepping in the solver. That is in Solver Configurations -> Time Dependent Solver -> Time Stepping
Sarah Chen
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Posted: 3 years ago 13 mar 2023, 19:25 GMT-4

What exactly would you recommend I change in the time stepping? I've set steps taken by solver to manual but not sure what to put for the other inputs.

What exactly would you recommend I change in the time stepping? I've set steps taken by solver to manual but not sure what to put for the other inputs.
Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago 14 mar 2023, 02:59 GMT-4

You need to resolve the waveform. I would recommend to start with period/10, so for a 50 Hz waveform with a 20 ms period it would be 2 ms. Depending on your results you may relax that to a longer time step.

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
You need to resolve the waveform. I would recommend to start with period/10, so for a 50 Hz waveform with a 20 ms period it would be 2 ms. Depending on your results you may relax that to a longer time step.

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