CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   how I can set the interface correctilly (http://www.cfd-online.com/Forums/cfx/90523-how-i-can-set-interface-correctilly.html)

happy July 13, 2011 04:29

how I can set the interface correctilly
 
Hi all,,
first of all, I need the interface because I model fluid and solid domain in my simulation. I have four walls of the chamber and fluid. I model conjugate heat conduction into the walls, and I did not set any of the interface region as boundary conditions. simply my geometry is chamber with opening top and heat source placed at the centre of the chamber floor, moreover, each wall have corner vertical gap and the chamber placed again inside big room with cieling.
As I read in documentation and in ANSYS website that when one does not set/identify any interface region as specific boundary condition and use it so that GGI is enough to make interface works ( means allow heat to transfer for example).
my equations, is that correct:D..:o?
another question, is it important to set another comnditions at teh interface such as HTC or heat flux??
f so , how??
let me give you example, in my case the temperature inside the chamber is variable so to set heat transfer coefficient I should to insert the outside temperature To and HTC ( variable). so my question is is acceptableto insert the both as expression,, please see below,,
qw=hc(To-Tw) ( no constant value in previous equation)
hc=qw/(To-Tw)
so I'm going to specify To&Tw as expression which depend on specific region at my model.
qw is avialable variable which I can specify easliy.
Please, I need some advices to know the right way to get heat transfer withing the walls ans even floor of the chamber.

I'm looking for hear from you as soon as possible:rolleyes:.

Regards

ghorrocks July 13, 2011 19:45

At a solid/fluid boundary you usually do not have to define anything. The HTC, heat fluxes and all that stuff are calculated out of the simulation.

happy July 14, 2011 22:07

question
 
hi again

so I did not need to specify the nonoverlap condition, especially, the heat transfer???

please I'm looking for advices

regards

ghorrocks July 15, 2011 06:24

No. At the non-overlap condition it needs to be told what to do with it - hence you have options to set HTC, wall conditions etc.

happy July 15, 2011 21:58

so why you told me first time I did not need to specify any thing????
please, if you not sure dont reply to my threads again,,
anyway, thanks

ghorrocks July 16, 2011 07:02

I admit I did not read your initial post very closely - it is quite difficult to understand and I do not have the time to go into every post in detail in the forum. So I answered the question I saw. If I missed the point of your first post I am sorry.

When an interface is joined properly there is nothing to define. For most interfaces this is case. It is only when the interface can have non-overlap areas that you have to define things.

But note if you are going to be pedantic, there are also things which may need to be defined on a joined interface, such as surface emissivities or surface source terms. But usually nothing needs to be defined.

happy July 16, 2011 22:39

hi again

1-what do mean the non-overlap areas exactly?
2-what the different between this and the locations of the interface?
3-can please advise me to write expression of heat flux or htc at the solid/fluid interface.

help me as soon as possible!!!!!!!!!!



regards

ghorrocks July 17, 2011 06:25

1 Attachment(s)
Here's a quick drawing. The red line is the interface between two domains.

Attachment 8439

You set HTC and all other parameters exactly the same as for a normal wall, just it is applied to the non-overlap region.


All times are GMT -4. The time now is 16:51.