# Functionally time-dependent boundary conditions

**URL:** <https://calculix.discourse.group/t/functionally-time-dependent-boundary-conditions/957>\
**Category:** Uncategorized\
**Created:** [January 21, 2022, 12:59pm UTC](https://calculix.discourse.group/t/functionally-time-dependent-boundary-conditions/957 "2022-01-21T12:59:20Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ttyUSB0](https://avatars.discourse-cdn.com/v4/letter/t/4af34b/32.png) [@ttyUSB0](https://calculix.discourse.group/u/ttyUSB0)\
**Post date:** [January 21, 2022, 12:59pm UTC](https://calculix.discourse.group/t/functionally-time-dependent-boundary-conditions/957/1 "2022-01-21T12:59:20Z")

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Hello!

Is CalculiX able to set functionally time-dependent boundary conditions?

I need to define irradiated heat power to faces of object as a function of time…

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**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [January 21, 2022, 1:11pm UTC](https://calculix.discourse.group/t/functionally-time-dependent-boundary-conditions/957/2 "2022-01-21T13:11:02Z")

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What you are looking for is called amplitude in CalculiX. You can define it this way:

```auto
*AMPLITUDE, NAME=amplitude_name
time, value, time, value, ...

```

Then call it in radiative heat flux definition like that:

`*RADIATE, AMPLITUDE=amplitude_name`

if you want to scale the sink temperature. Or like that:

`*RADIATE, RADIATION AMPLITUDE=amplitude_name`

if you want to scale the emissivity.

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<div class="post-metadata">

**Author:** ![ttyUSB0](https://avatars.discourse-cdn.com/v4/letter/t/4af34b/32.png) [@ttyUSB0](https://calculix.discourse.group/u/ttyUSB0)\
**Post date:** [January 21, 2022, 2:01pm UTC](https://calculix.discourse.group/t/functionally-time-dependent-boundary-conditions/957/3 "2022-01-21T14:01:22Z")

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Thank you, Calc\_em!  
I definitely need to read the manual…