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Step function in a time-dependent problem

Posted Jan 15, 2019, 9:55 a.m. EST 2 Replies

Marco Balmer
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Hello everyone,

I am trying to implement a step function in my time-dependent problem where I want to lower the temperature of a constant temperature boundary from 40°C to 20°C after 10min (600s) of running the model. However, I always get the error "Failed to find consistent initial values. Last time step is not converged." Running the model without the step function works.

The details of my step function are: Location 600, From 0, To 1. Implemented into the constant temperature boundary like this: T0 = 40 - (20*step1(t)) [degC]

Thanks for your help!

2 Replies Last Post Jan 17, 2019, 12:52 p.m. EST
Edgar J. Kaiser Certified Consultant
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Posted: 6 years ago Jan 15, 2019, 12:23 p.m. EST

Hi Marco,

you need to take care to smooth the step sufficiently and to make sure that the timestepping resolves the smoothed function. You may need to introduce manual time stepping for that.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi Marco, you need to take care to smooth the step sufficiently and to make sure that the timestepping resolves the smoothed function. You may need to introduce manual time stepping for that. Cheers Edgar
Marco Balmer
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Posted: 6 years ago Jan 17, 2019, 12:52 p.m. EST

Hi Edgar,

Thanks for your reply! How exactly do I implement the smoothing into my model?

Cheers Marco

Hi Edgar, Thanks for your reply! How exactly do I implement the smoothing into my model? Cheers Marco

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