poor calculation with temparture-dependant specific heat

ryanmoser · December 30, 2012, 03:29

I am trying to simulate the melting process with the method of effective heat capacity, which requires FLUENT to solve energy equations with changing specific heat. I wrote a udf to specify the specific heat. However, it doesn't help. Temperature rising rate is far beyond what it should be.
Then I tried to work with the constant specific heat, and the result was more acceptable, but not precise enough.
Could anyone tell me what should I be aware of to improve the iteration stability and precision with temperature-dependent property?
Thank you so much!

Far · December 30, 2012, 05:59

I guess it the problem of core flow physics available in Fluent rather than the specific heat.

beer · January 2, 2013, 08:43

Did you consider setting the enthalpy, too? This was a problem in my first simulations with temperature-dependent Cp.

msaeedsadeghi · January 3, 2013, 01:32

Yes, You should also decrease energy URF.

December 30, 2012, 03:29	poor calculation with temparture-dependant specific heat	#1
ryanmoser New Member Moser Join Date: Dec 2010 Posts: 12 Rep Power: 15	I am trying to simulate the melting process with the method of effective heat capacity, which requires FLUENT to solve energy equations with changing specific heat. I wrote a udf to specify the specific heat. However, it doesn't help. Temperature rising rate is far beyond what it should be. Then I tried to work with the constant specific heat, and the result was more acceptable, but not precise enough. Could anyone tell me what should I be aware of to improve the iteration stability and precision with temperature-dependent property? Thank you so much!

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December 30, 2012, 05:59		#2
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	I guess it the problem of core flow physics available in Fluent rather than the specific heat.

January 2, 2013, 08:43		#3
beer Member Join Date: Dec 2012 Posts: 92 Rep Power: 13	Did you consider setting the enthalpy, too? This was a problem in my first simulations with temperature-dependent Cp.

January 3, 2013, 01:32		#4
msaeedsadeghi Senior Member SSL Join Date: Oct 2012 Posts: 226 Rep Power: 14	Yes, You should also decrease energy URF.