Thermal analysis in Optistruct - Gap elements

Mateusz L

Hi,
I have a problem with heat transfer in Optistruct - I have  solid elements connected with shell elements using Gap elements, heat source is temperature on solid elements and there is two cases:
1. gap elements work properly when there is only conduction heat transfer between those two components

2. gap elements do not work properly when I add convection between ambient and shell elements.

 

Do anyone have an idea what is wrong and could help me solve this issue?

Altair Forum User

HI @Mateusz L

 

I don't think convection needs a medium to transfer like conduction and that is why you don't see any results. 

Mateusz L

Thanks for Your answer, I had a break and now I came back to this issue.
 

I'm afraid I didn't explained it well.

The thing is that between shell and solid part I need a medium so I'm using gap elements. 
When I run analysis as a result I see solid part have temperature like hot side e.g. 500 C and shell elements (part 1) have an ambient temperature e.g.25 C
It looks like gap elements do not transfer conduction between them.



When I don't consider convection gap elements transfer heat and both parts (1 and 2 ) have hot side temperature.

Hope now situation is clear. Do anyone have an idea how to solve it?

Altair Forum User

Hi,

 

I have it clear in my head now. I will check with experts and will get back to you. 

Mateusz L

Hi, do you have any information about a problem? 

Lucia R

Hi!

I am working in a similar problem, do you have any solution?

Adriano A. Koga

gap elements or using freeze contact between 2 surfaces will provide conductive heat transfer accross the parts.

For convection you would need to add a special convection group in the shell side, and define a ambient temperature and convective coefficient. There's a tutorial in OS Help for this kind of problems (convection). Contacts and gaps i don't recall having a tutorial for thermal.

Lucia R

I want to transfer heat from a hot surface to a cold surface using convection.

I have created a convection surface for both surfaces (hot and cold) and a node between the surfaces. Then, I have changed both surfaces type to slave and I selected the node between them as TA1 in the CONV card.

The calculations run until the end without errors but the results are not the expected because there isnt any heat transfer between both surfaces.

Do you know what i am doing wrong?

Thanks for your help!

 

Adriano A. Koga

as this is natural convection i believe you will have only heat transfer between your surfaces individually to the ambient.

if i'm not mistaken, in order to transfer from one to the other, i believe you would need to have forced convection, thus CFD would be needed (TFSTI).