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Variable thickness

Posted Dec 18, 2016, 9:48 a.m. EST Heat Transfer & Phase Change, Geometry, Materials, Parameters, Variables, & Functions, Studies & Solvers Version 5.2a 3 Replies

Glenn Pennings
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Hello helpers,

Currently i working on a simulations of a wall section.
In this case its simplified and only existing of a brick outside wall, insulation layer and gypsum on the inside.

In order to full my needs, i would like to vary the thickness of the insulation layer (in between the other layer) to see what exactly happens regarding temperatures on certain locations and the heat fluxes.

How can i set this up in Comsol 5.2a?

For info; currently im also using an interpolation for the outside temperature

With kind regards,

Glenn

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3 Replies Last Post Dec 19, 2016, 1:07 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 8 years ago Dec 18, 2016, 10:09 a.m. EST
Hi

if you have 3 "materials" make three domains, with a Parameter (from Definition Parameter) defining the middle isolation thickness, brick, isolation, gypsum.
Then add a Parametric Sweep before your main solver node and define a range for the parameter.

Your geometry will be adapted for each solver run and you can then plot whatever you want as a function of your parameter = isolation thickness.
Up to you, in your equations, to define which other vales of the wall thickness to vary/ adapt i.e. constant wall thickness, constant brick thickness ...

Check the COMSOL site videos on Parametric Sweep Solvers

--
Good luck
Ivar
Hi if you have 3 "materials" make three domains, with a Parameter (from Definition Parameter) defining the middle isolation thickness, brick, isolation, gypsum. Then add a Parametric Sweep before your main solver node and define a range for the parameter. Your geometry will be adapted for each solver run and you can then plot whatever you want as a function of your parameter = isolation thickness. Up to you, in your equations, to define which other vales of the wall thickness to vary/ adapt i.e. constant wall thickness, constant brick thickness ... Check the COMSOL site videos on Parametric Sweep Solvers -- Good luck Ivar
Glenn Pennings
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Posted: 8 years ago Dec 19, 2016, 9:23 a.m. EST
Thank you very much Ivar
I managed to do it.

However, i end up with a follow up question.
Added, i computed the outgoing heat flux during the year for different Tinsul (insulation thickness).
Now i would like to calculate the surface under the graph (so the total heat flux in the year) and set the up against the Tinsul. So on the y-axis the total heat flux in the year and x-axis the Tinsul. For the total heat flux only the positive numbers some be taken into account (i need to neglect the inward heat flux what occurs when the outside temperature is higher then the inside temperature). How can i set this up easliy?

Thanks on beforehand
Thank you very much Ivar I managed to do it. However, i end up with a follow up question. Added, i computed the outgoing heat flux during the year for different Tinsul (insulation thickness). Now i would like to calculate the surface under the graph (so the total heat flux in the year) and set the up against the Tinsul. So on the y-axis the total heat flux in the year and x-axis the Tinsul. For the total heat flux only the positive numbers some be taken into account (i need to neglect the inward heat flux what occurs when the outside temperature is higher then the inside temperature). How can i set this up easliy? Thanks on beforehand

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Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 8 years ago Dec 19, 2016, 1:07 p.m. EST
Hi

in COMSOL you have many "operators", also time-integration ones (see the help or the doc), you can also make a Derived Variable and dump the results into a table and then apply operations there too.

In your case, if you want only the positive heat flux part you need to use an explicit time integration and multiply your variable (integrated over the correct boundary) by the Boolean expression timeintegration_of( your_var*(your_var>0) )


another way is to define a global variable (see and search the BLOG for time integration) to directly integrate your heat flux (the positive part of)

--
Good luck
Ivar
Hi in COMSOL you have many "operators", also time-integration ones (see the help or the doc), you can also make a Derived Variable and dump the results into a table and then apply operations there too. In your case, if you want only the positive heat flux part you need to use an explicit time integration and multiply your variable (integrated over the correct boundary) by the Boolean expression timeintegration_of( your_var*(your_var>0) ) another way is to define a global variable (see and search the BLOG for time integration) to directly integrate your heat flux (the positive part of) -- Good luck Ivar

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