Problem with heat flow

ayoxon · February 17, 2015, 12:40

I am analysing the heat flow in a room with a radiator. The problem I'm having is that the flow is not dispersing into the room, just building up heat at the radiator.

I have got the radiator set at a constant temperature of 333K. The only way I got it it flow around the room was to use heat flux instead of a constant temperature, but then the temperature reached 5000K, which is obviously not suitable.

I'm very new to this so not sure what to write, but I'll try to asnwer any questions about the project

edoan · February 17, 2015, 15:43

Hey Andy, it sounds like you may not have gravity enabled. If you are using the boussinesq approx. put the operating temp as ambient. theres some info on natural convection in the users guide you can look at if you havn't already done so

ayoxon · February 17, 2015, 16:13

Thanks for the reply! I already had gravity on, but I changed the air to boussinesq but now I have an error "Divergent detected in AMG solver: x-momentum".

I think maybe my geometry is the problemt. When I created a new plane on modeller, I couldn't get the x and z in the same direction as the original plane. It then means the xz plane for my inlet-heat (radiator) is different to the other planes. It's extremely hard to explain, hopefully this is enough information.

ayoxon · February 17, 2015, 16:39

Actually it can't be that as I've tried it with my other geometries and and I still get the error.

edoan · February 19, 2015, 11:34

Hey Andy, for boussinesq approx make sure your thermal expansion coefficient is an appropriate value in the materials tab.. are you using first order discretization? are you sure the mesh is good close to the heat source?

ayoxon · February 21, 2015, 11:35

Changed my project quite a bit and it's a lot better.

Doing it as a transient flow, using ideal gas, have changed my mesh to make it finer near the heat source.

All seems a lot better. Thanks for the help edoan!

February 17, 2015, 12:40	Problem with heat flow	#1
ayoxon New Member andy Join Date: Feb 2015 Posts: 9 Rep Power: 11	I am analysing the heat flow in a room with a radiator. The problem I'm having is that the flow is not dispersing into the room, just building up heat at the radiator. I have got the radiator set at a constant temperature of 333K. The only way I got it it flow around the room was to use heat flux instead of a constant temperature, but then the temperature reached 5000K, which is obviously not suitable. I'm very new to this so not sure what to write, but I'll try to asnwer any questions about the project Last edited by ayoxon; February 17, 2015 at 15:21.

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February 17, 2015, 15:43		#2
edoan Member Ethan Doan Join Date: Oct 2012 Location: Canada Posts: 90 Rep Power: 14	Hey Andy, it sounds like you may not have gravity enabled. If you are using the boussinesq approx. put the operating temp as ambient. theres some info on natural convection in the users guide you can look at if you havn't already done so

February 17, 2015, 16:13		#3
ayoxon New Member andy Join Date: Feb 2015 Posts: 9 Rep Power: 11	Thanks for the reply! I already had gravity on, but I changed the air to boussinesq but now I have an error "Divergent detected in AMG solver: x-momentum". I think maybe my geometry is the problemt. When I created a new plane on modeller, I couldn't get the x and z in the same direction as the original plane. It then means the xz plane for my inlet-heat (radiator) is different to the other planes. It's extremely hard to explain, hopefully this is enough information.

February 17, 2015, 16:39		#4
ayoxon New Member andy Join Date: Feb 2015 Posts: 9 Rep Power: 11	Actually it can't be that as I've tried it with my other geometries and and I still get the error.

February 19, 2015, 11:34		#5
edoan Member Ethan Doan Join Date: Oct 2012 Location: Canada Posts: 90 Rep Power: 14	Hey Andy, for boussinesq approx make sure your thermal expansion coefficient is an appropriate value in the materials tab.. are you using first order discretization? are you sure the mesh is good close to the heat source?

February 21, 2015, 11:35		#6
ayoxon New Member andy Join Date: Feb 2015 Posts: 9 Rep Power: 11	Changed my project quite a bit and it's a lot better. Doing it as a transient flow, using ideal gas, have changed my mesh to make it finer near the heat source. All seems a lot better. Thanks for the help edoan!