Hot and cold spots along the axes

MSHowes · February 11, 2013, 16:17

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Hello,
I'm modeling a rotating cylindrical flow and I'm seeing narrow hot and cold areas appearing on either side of the x and y axes (my axis of rotation is z). The temperature should remain uniform so this looks like numerical error. Has anybody seen this?

ghorrocks · February 11, 2013, 18:06

Have you read the FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

MSHowes · February 12, 2013, 09:53

Hi, thank you for your response. Yes, I have read the FAQ. Unfortunately it basically says "try everything"-- I wish I had the time. What's puzzling to me is that my momentum and pressure results look great; it's just the temperature that exhibits this error along the axes. I'm tracking the residuals and the heat transfer residuals are on a par with the momentum residuals. I've tested it on three grids so far. The hot/cold spots appear within a few time-steps and never go away.

ghorrocks · February 12, 2013, 18:44

With such a general question with no description of what you are modelling, then how do you expect anything but a general answer? But the real answer will be one of the things discussed in the FAQ - your job is to find which one.

February 11, 2013, 16:17	Hot and cold spots along the axes	#1
MSHowes New Member Join Date: Sep 2012 Posts: 8 Rep Power: 6	Sponsored Links Hello, I'm modeling a rotating cylindrical flow and I'm seeing narrow hot and cold areas appearing on either side of the x and y axes (my axis of rotation is z). The temperature should remain uniform so this looks like numerical error. Has anybody seen this?

February 12, 2013, 09:53	hot and cold spots	#3
MSHowes New Member Join Date: Sep 2012 Posts: 8 Rep Power: 6	Hi, thank you for your response. Yes, I have read the FAQ. Unfortunately it basically says "try everything"-- I wish I had the time. What's puzzling to me is that my momentum and pressure results look great; it's just the temperature that exhibits this error along the axes. I'm tracking the residuals and the heat transfer residuals are on a par with the momentum residuals. I've tested it on three grids so far. The hot/cold spots appear within a few time-steps and never go away.

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February 11, 2013, 18:06		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,736 Rep Power: 106	Have you read the FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

February 12, 2013, 18:44		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,736 Rep Power: 106	With such a general question with no description of what you are modelling, then how do you expect anything but a general answer? But the real answer will be one of the things discussed in the FAQ - your job is to find which one.