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Temperature change from expansion of air

Posted Apr 8, 2013, 11:38 a.m. EDT Fluid & Heat, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.4 3 Replies

Adam Bateman
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I am trying to model the flow fields of a fluid (air) traveling through an orifice. I have a working model that works great using only the laminar flow module. However, the viscosity of the fluid is always constant as there is no temperature change. So, I want the model to also calculate the temperature change due to the compression of the fluid in the nozzle and then the expansion of the gas following the nozzle. Is there a simple physics to add that will include this temperature change? I would like somthing similar to the high-mach-number flow physics, but without having to use this module as the Mach number does not get above ~0.3. Any help would be great.
3 Replies Last Post Jan 17, 2014, 11:47 a.m. EST
Niklas Rom COMSOL Employee

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Posted: 1 decade ago Apr 9, 2013, 4:22 a.m. EDT
Use "Nonisothermal flow".
Niklas

I am trying to model the flow fields of a fluid (air) traveling through an orifice. I have a working model that works great using only the laminar flow module. However, the viscosity of the fluid is always constant as there is no temperature change. So, I want the model to also calculate the temperature change due to the compression of the fluid in the nozzle and then the expansion of the gas following the nozzle. Is there a simple physics to add that will include this temperature change? I would like somthing similar to the high-mach-number flow physics, but without having to use this module as the Mach number does not get above ~0.3. Any help would be great.


Use "Nonisothermal flow". Niklas [QUOTE] I am trying to model the flow fields of a fluid (air) traveling through an orifice. I have a working model that works great using only the laminar flow module. However, the viscosity of the fluid is always constant as there is no temperature change. So, I want the model to also calculate the temperature change due to the compression of the fluid in the nozzle and then the expansion of the gas following the nozzle. Is there a simple physics to add that will include this temperature change? I would like somthing similar to the high-mach-number flow physics, but without having to use this module as the Mach number does not get above ~0.3. Any help would be great. [/QUOTE]
Adam Bateman
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Posted: 1 decade ago Apr 9, 2013, 12:58 p.m. EDT
Thank you for the reply. I tried this method, and I get the same temperature across the entire geometry. As there is no outside heat source/sink.
Thank you for the reply. I tried this method, and I get the same temperature across the entire geometry. As there is no outside heat source/sink.
nussbac
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Posted: 1 decade ago Jan 17, 2014, 11:47 a.m. EST
So this thread was unsolved?

I am experiencing the same problem, only I am modelling water flow under very high pressure through an orifice, and wnat to model the expected Joule-Thompson heating that occurs.
Like Adam Bateman, I am using the nitf module.
There appears to be no statement of the JT Coefficient in the material properties.

What is the answer???


Thank you for the reply. I tried this method, and I get the same temperature across the entire geometry. As there is no outside heat source/sink.





--

So this thread was unsolved? I am experiencing the same problem, only I am modelling water flow under very high pressure through an orifice, and wnat to model the expected Joule-Thompson heating that occurs. Like Adam Bateman, I am using the nitf module. There appears to be no statement of the JT Coefficient in the material properties. What is the answer??? [QUOTE] Thank you for the reply. I tried this method, and I get the same temperature across the entire geometry. As there is no outside heat source/sink. [/QUOTE] --

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