How to quickly tilt objects and see the flow?

federernadal · February 23, 2016, 16:50

Hi,

I am trying to model airflow over a coil. I would like to see the airflow patterns at varying tilts of the coil.

How do I do this?

ghorrocks · February 23, 2016, 16:52

This sounds like a basic CFD task. This is well covered by the tutorials provided with your meshing software and CFX.

federernadal · February 23, 2016, 17:01

Is this a CFD or a Geometry task?

federernadal · February 23, 2016, 17:28

I guess I wasnt too clear. I am looking to Parametrize the angle that I rotate this coil against the airflow mass exiting.

Just not too sure on how exactly to link them together.

ghorrocks · February 24, 2016, 05:11

There are plenty of tutorials in ANSYS Workbench which show how to use parameters as well.

federernadal · March 1, 2016, 10:18

So I have a coil, and I made an enclosure.

I do a Boolean Subtract to subtract the coil out of the box (I preserve bodies though).

I create 2 domains. Porous for the coil and fluid for the air.

BCs on the enclosure walls - 1 mass flow inlet and 1 p=0 outlet

Why am I getting a negative element size error?

Thanks.

ghorrocks · March 1, 2016, 16:52

FAQ: http://www.cfd-online.com/Wiki/Ansys..._went_wrong.3F

Or if you get this error and you are not doing an FSI simulation then you have a severe problem with your mesh. Use the tools in your meshing software to mesh the domain properly.

federernadal · March 2, 2016, 00:41

Glenn, thanks - got past that error by adding some mesh controls. But after getting crappy results I am beginning to question my overarching strategy.

Need to go over my plan to simulate a condenser coil with refrigerant running through it (to heat air passing over/through it) using CFX.

I want to model the coil as a rectangular plate - porous domain (actual geometry is wayyy to complex to model). Then, place an enclosure - fluid domain (air).

Have a BC with air inlet on one side face of enclosure using a mass flow rate and leaving through the other side face with avg static pressure of 0.

However, I also want to model heat transfer. When I generate the porous domain, I am not sure how to have it be at a certain temperature so it exchanges heat with the air above it. I want the refrigerant running through the porous domain be at say 140 deg fahrenheit. And the air I will at the inlet face at around 70 deg fahrenheit.

I get all blue lines for velocity and temperature (no heat exchanged) all over (crappy results) - Should I manually place walls on my coil/porous domain? Btw, do wall BCs on porous domains mean fully solid faces or are they still porous?

federernadal · March 3, 2016, 09:24

Help? Anybody?

February 23, 2016, 16:50	How to quickly tilt objects and see the flow?	#1
federernadal Member Join Date: Oct 2015 Posts: 56 Rep Power: 10	Hi, I am trying to model airflow over a coil. I would like to see the airflow patterns at varying tilts of the coil. How do I do this?

February 23, 2016, 16:52		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,816 Rep Power: 144	This sounds like a basic CFD task. This is well covered by the tutorials provided with your meshing software and CFX.

February 23, 2016, 17:01		#3
federernadal Member Join Date: Oct 2015 Posts: 56 Rep Power: 10	Is this a CFD or a Geometry task?

February 23, 2016, 17:28		#4
federernadal Member Join Date: Oct 2015 Posts: 56 Rep Power: 10	I guess I wasnt too clear. I am looking to Parametrize the angle that I rotate this coil against the airflow mass exiting. Just not too sure on how exactly to link them together.

February 24, 2016, 05:11		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,816 Rep Power: 144	There are plenty of tutorials in ANSYS Workbench which show how to use parameters as well.

March 1, 2016, 16:52		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,816 Rep Power: 144	FAQ: http://www.cfd-online.com/Wiki/Ansys..._went_wrong.3F Or if you get this error and you are not doing an FSI simulation then you have a severe problem with your mesh. Use the tools in your meshing software to mesh the domain properly.

March 2, 2016, 00:41		#8
federernadal Member Join Date: Oct 2015 Posts: 56 Rep Power: 10	Glenn, thanks - got past that error by adding some mesh controls. But after getting crappy results I am beginning to question my overarching strategy. Need to go over my plan to simulate a condenser coil with refrigerant running through it (to heat air passing over/through it) using CFX. I want to model the coil as a rectangular plate - porous domain (actual geometry is wayyy to complex to model). Then, place an enclosure - fluid domain (air). Have a BC with air inlet on one side face of enclosure using a mass flow rate and leaving through the other side face with avg static pressure of 0. However, I also want to model heat transfer. When I generate the porous domain, I am not sure how to have it be at a certain temperature so it exchanges heat with the air above it. I want the refrigerant running through the porous domain be at say 140 deg fahrenheit. And the air I will at the inlet face at around 70 deg fahrenheit. I get all blue lines for velocity and temperature (no heat exchanged) all over (crappy results) - Should I manually place walls on my coil/porous domain? Btw, do wall BCs on porous domains mean fully solid faces or are they still porous?

March 3, 2016, 09:24		#9
federernadal Member Join Date: Oct 2015 Posts: 56 Rep Power: 10	Help? Anybody?