Units in 2D analysis

crinoid · March 5, 2019, 09:27

Hi,
When using Fluent with a 2D mesh, the results which are shown are per unit of length?
I am studying the heat transfer between some tubes in cross-flow with cold air and Fluent computes the pressure drop (pa) and heat exchange (w). Do I have to multiply those numbers by the length of my tubes?
Thanks in advance

CFD-fellow · March 5, 2019, 23:57

Hi,
The answer of your question is completely dependent on the result variable definition and derivation. For example the pressure drop in cross flow is not dependent on the length of tubes while heat exchange is dependent and the value is calculated per unit of length and must be multiplied by the length of tubes.

crinoid · March 6, 2019, 05:21

Sounds logic, thank you for your answer!!

MKuhn · March 6, 2019, 09:57

Some values like volume, flow rate and volume integrals are calculated with the Reference Depth in a 2D-analysis, which you can change under "Setup" and "Reference Values"

crinoid · March 7, 2019, 08:14

Ok, thanks!!
Would it be possible that the heat flux was express per units of area (considering pi * diameter * 1 m)?

MKuhn · March 7, 2019, 08:43

By default settings yes.

March 5, 2019, 09:27	Units in 2D analysis	#1
crinoid New Member crinoid Join Date: Jan 2019 Posts: 22 Rep Power: 7	Hi, When using Fluent with a 2D mesh, the results which are shown are per unit of length? I am studying the heat transfer between some tubes in cross-flow with cold air and Fluent computes the pressure drop (pa) and heat exchange (w). Do I have to multiply those numbers by the length of my tubes? Thanks in advance

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March 5, 2019, 23:57		#2
CFD-fellow Senior Member Behrooz Jamshidi Join Date: Apr 2013 Posts: 110 Rep Power: 13	Hi, The answer of your question is completely dependent on the result variable definition and derivation. For example the pressure drop in cross flow is not dependent on the length of tubes while heat exchange is dependent and the value is calculated per unit of length and must be multiplied by the length of tubes.

March 6, 2019, 05:21		#3
crinoid New Member crinoid Join Date: Jan 2019 Posts: 22 Rep Power: 7	Sounds logic, thank you for your answer!!

March 6, 2019, 09:57		#4
MKuhn Senior Member Moritz Kuhn Join Date: Apr 2010 Location: Germany, Dresden Posts: 218 Rep Power: 17	Some values like volume, flow rate and volume integrals are calculated with the Reference Depth in a 2D-analysis, which you can change under "Setup" and "Reference Values"

March 7, 2019, 08:14		#5
crinoid New Member crinoid Join Date: Jan 2019 Posts: 22 Rep Power: 7	Ok, thanks!! Would it be possible that the heat flux was express per units of area (considering pi * diameter * 1 m)?

March 7, 2019, 08:43		#6
MKuhn Senior Member Moritz Kuhn Join Date: Apr 2010 Location: Germany, Dresden Posts: 218 Rep Power: 17	By default settings yes.