what after create my geometry

happy · November 19, 2010, 03:12

Hi ghorrocks
How R U today? I hope U fine and happy.
First of all, I try to simulate tornato chamber and I could draw my geometry, but I wonder how I treat with heat resouce regarding building it...firstly, I treat with it as surface but I could not make the correct sitting for it...I mean I want to set the kind of heat transfer by natural convection and radiations, but I can not get it.please, look at my picure care fully and ask me if U need extra information......
and see
http://www.cfd-online.com/Forums/ans...need-help.html
Do I need to use sub-domen to create my heat resouce and how I can set correctly my boundary conditions at it.

I am sorry because I have problem to attach my files.!!!!!!!!

Attachment 5497

Attachment 5498

Best Regards

ghorrocks · November 19, 2010, 04:46

How does the heat transfer and radiation act? Does it heat surfaces and that transfers to the fluid by natural convection? Then wall boundary patches are all that are required. Or does the heat transfer act on the fluid directly? In that case you might need sub-domains to provide a heat source. If the radiation acts on the fluid directly you might need to specify the radiation source and some features of the fluid which make it affected by radiation.

But you would have to describe what you are doing better for you to help you.

happy · November 19, 2010, 11:27

Hi, again...
Thanks for your reply and explanation.

Originally, I'm going to simulate a fire whirl phenomenon which has to be generate by this chamber, but firstly, I want to examine this phenomenon by using heat source instead of fire So. my heat source that U can see at bottom of the chamber is to introduce heat into it and by vortex, tornado can be created. Let me come back to heat source, which is an inlet boundary condition.
Which better I consider it as surface (specified region before generate the mesh) which has a different condition with regard to the rest of remained surface at the bottom of the chamber?
I mean about the heat source as surface that it is considered as a flat heater at a high constant temperatures and generate volumetric constant heat flux also transferred heat will affect fluid itself, the walls and floor. In addition it will be affected by boundary conditions of 4 slits that generate sort of vortex (angler velocity) which is so important to create whirling flow inside the chamber.
My B.Cs will be located on four slits, at heat source, floor, and at the top which is opened to the atmosphere.
My fluid is air and I need to simulate the swirling flow in order to have details about how temp. changes and velocity...and I want to present swirling flow by using streamlines.
Finally, I hope my description is perfect.

Thanks in advance.

ghorrocks · November 19, 2010, 18:04

You hopefully will be able to generate this simple flow (ie just the heat source on the bottom) with a high temperature or high heat flux applied to the bottom face. Note that most 2 equation turbulence models will almost certainly kill the tornado, you might be able to do it with SST but you will probably need a RSM model, or LES. RSM and LES models are not easy to do and are not recommended for beginners.

This is not a straight forward model to do. I hope you have some CFD experience, or lots of time to learn.

happy · November 19, 2010, 21:49

Hi

Thanks for your good input.
In reality, I need U to advise me which tutorials can give mr deep undrstand about these models LES, RSM.
I everyday work with ANSYSand learn deeply...
and another question, which is perfect to simulate my chamber by ANSYS-CFX or by ANSYS-FLUENT, where I'm going to simulate my system by both.

Finally, is it possible to gather natural convection and radiation into one heat source?
Please,help me by your avices which are always helpful.

Kind Regards.

ghorrocks · November 20, 2010, 07:07

There are no tutorials on RSM or LES. They are advanced topics - that's why I say not for beginners. Your best bet is to go to the library and get some textbooks on RSM and LES. They are the best place for ideas of how to run these models.

Both CFX and Fluent can do the model you propose. Use which ever you are happiest with.

Yes, heat sources can be combined.

happy · November 26, 2010, 04:22

Hi ghorrocks

Your recommenditions are so useful and I'm going to take them and need more

....So do not give me up and direct my thoughts please.

Best Regards.

November 19, 2010, 03:12	what after create my geometry	#1
happy Senior Member Safia Join Date: Oct 2010 Location: Australia Posts: 161 Rep Power: 16	Hi ghorrocks How R U today? I hope U fine and happy. First of all, I try to simulate tornato chamber and I could draw my geometry, but I wonder how I treat with heat resouce regarding building it...firstly, I treat with it as surface but I could not make the correct sitting for it...I mean I want to set the kind of heat transfer by natural convection and radiations, but I can not get it.please, look at my picure care fully and ask me if U need extra information...... and see http://www.cfd-online.com/Forums/ans...need-help.html Do I need to use sub-domen to create my heat resouce and how I can set correctly my boundary conditions at it. I am sorry because I have problem to attach my files.!!!!!!!! Attachment 5497 Attachment 5498 Best Regards Last edited by happy; December 9, 2010 at 07:33.

November 19, 2010, 11:27	Describtion my chamber	#3
happy Senior Member Safia Join Date: Oct 2010 Location: Australia Posts: 161 Rep Power: 16	Hi, again... Thanks for your reply and explanation. Originally, I'm going to simulate a fire whirl phenomenon which has to be generate by this chamber, but firstly, I want to examine this phenomenon by using heat source instead of fire So. my heat source that U can see at bottom of the chamber is to introduce heat into it and by vortex, tornado can be created. Let me come back to heat source, which is an inlet boundary condition. Which better I consider it as surface (specified region before generate the mesh) which has a different condition with regard to the rest of remained surface at the bottom of the chamber? I mean about the heat source as surface that it is considered as a flat heater at a high constant temperatures and generate volumetric constant heat flux also transferred heat will affect fluid itself, the walls and floor. In addition it will be affected by boundary conditions of 4 slits that generate sort of vortex (angler velocity) which is so important to create whirling flow inside the chamber. My B.Cs will be located on four slits, at heat source, floor, and at the top which is opened to the atmosphere. My fluid is air and I need to simulate the swirling flow in order to have details about how temp. changes and velocity...and I want to present swirling flow by using streamlines. Finally, I hope my description is perfect. Thanks in advance.

November 19, 2010, 21:49	need extra recommindations	#5
happy Senior Member Safia Join Date: Oct 2010 Location: Australia Posts: 161 Rep Power: 16	Hi Thanks for your good input. In reality, I need U to advise me which tutorials can give mr deep undrstand about these models LES, RSM. I everyday work with ANSYSand learn deeply... and another question, which is perfect to simulate my chamber by ANSYS-CFX or by ANSYS-FLUENT, where I'm going to simulate my system by both. Finally, is it possible to gather natural convection and radiation into one heat source? Please,help me by your avices which are always helpful. Kind Regards.

November 26, 2010, 04:22	Please, do not go away	#7
happy Senior Member Safia Join Date: Oct 2010 Location: Australia Posts: 161 Rep Power: 16	Hi ghorrocks Your recommenditions are so useful and I'm going to take them and need more....So do not give me up and direct my thoughts please. Best Regards.

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November 19, 2010, 04:46		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	How does the heat transfer and radiation act? Does it heat surfaces and that transfers to the fluid by natural convection? Then wall boundary patches are all that are required. Or does the heat transfer act on the fluid directly? In that case you might need sub-domains to provide a heat source. If the radiation acts on the fluid directly you might need to specify the radiation source and some features of the fluid which make it affected by radiation. But you would have to describe what you are doing better for you to help you.

November 19, 2010, 18:04		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	You hopefully will be able to generate this simple flow (ie just the heat source on the bottom) with a high temperature or high heat flux applied to the bottom face. Note that most 2 equation turbulence models will almost certainly kill the tornado, you might be able to do it with SST but you will probably need a RSM model, or LES. RSM and LES models are not easy to do and are not recommended for beginners. This is not a straight forward model to do. I hope you have some CFD experience, or lots of time to learn.

November 20, 2010, 07:07		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	There are no tutorials on RSM or LES. They are advanced topics - that's why I say not for beginners. Your best bet is to go to the library and get some textbooks on RSM and LES. They are the best place for ideas of how to run these models. Both CFX and Fluent can do the model you propose. Use which ever you are happiest with. Yes, heat sources can be combined.