# Prescribe boundary temperature conditions in melt model

**URL:** <https://community.geodynamics.org/t/prescribe-boundary-temperature-conditions-in-melt-model/1696>\
**Category:** ASPECT\
**Created:** [February 17, 2021, 1:51pm UTC](https://community.geodynamics.org/t/prescribe-boundary-temperature-conditions-in-melt-model/1696 "2021-02-17T13:51:27Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Xie](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/xie/32/707_2.png) [@Xie](https://community.geodynamics.org/u/Xie)\
**Post date:** [February 17, 2021, 1:51pm UTC](https://community.geodynamics.org/t/prescribe-boundary-temperature-conditions-in-melt-model/1696/1 "2021-02-17T13:51:28Z")

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Hi all,

I am currently studying the melt model in ASPECT (e.g., global\_melt, Dannberg & Heister, 2016), and the content of this part is still new to me.

I’d like to :

1. Change the geometry to a spherical shell.

2. Prescribe the boundary temperature model as ‘dynamic core’

I want to know how to prescribe the temperature-related boundary conditions so that the upper (or surface) and lower (or bottom) temperatures of this geometry model correspond to the outer/inner temperature in the dynamic core. I think the key to this problem lies in how to set initial temperature boundary condition ?

Assuming I have,

```auto
set Adiabatic surface temperature = 1600

subsection Geometry model
  set Model name = spherical shell
  subsection Spherical shell
    set Inner radius = 1900e3
    set Outer radius = 3000e3
    set Opening angle = 90
  end
end

subsection Boundary temperature model
  set Model name = dynamic core
  subsection Dynamic core
    set Inner temperature = 2100
    set Outer temperature = 300 # 300K is the actual surface temperature.
    ...
  end
end

```

If the _subsection Initial temperature model_ similar to the one used in global\_melt is still used here, then how should I set this part ? or is there a better way ?

Best,

Xie

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<div class="post-metadata">

**Author:** ![bangerth](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/bangerth/32/52_2.png) [@bangerth](https://community.geodynamics.org/u/bangerth)\
**Post date:** [February 22, 2021, 7:15pm UTC](https://community.geodynamics.org/t/prescribe-boundary-temperature-conditions-in-melt-model/1696/2 "2021-02-22T19:15:40Z")

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Xie,  
I have to admit that I don’t quite understand your question ☹ The initial temperature is conceptually separate from the boundary temperature. You can choose them independently, and ASPECT makes no assumption about their relationship.

I assume you have read about the parameter that need to be set for the dynamic core plugin, and what they mean?

Best  
Wolfgang

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<div class="post-metadata">

**Author:** ![Xie](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/xie/32/707_2.png) [@Xie](https://community.geodynamics.org/u/Xie)\
**Post date:** [February 26, 2021, 3:41am UTC](https://community.geodynamics.org/t/prescribe-boundary-temperature-conditions-in-melt-model/1696/3 "2021-02-26T03:41:28Z")

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Sorry for the first post that confused you. Let me rephrase it, if I want to apply the dynamic core into a geometry of box. Then what I should do to make it happen? The purpose of doing so is to perform a more realistic simulation. I realize that I may have to modify the source code of dynamic core, especially the snippet (starting from line 657) about ’ calculate core mantle boundary heat flow’ in update function if I understand it correct.

Best,  
Xie