
[Sponsors] 
How to define a report to evaluate different "impacts" on temperature in a point? 

LinkBack  Thread Tools  Search this Thread  Display Modes 
May 15, 2020, 11:43 
How to define a report to evaluate different "impacts" on temperature in a point?

#1 
New Member
Josh
Join Date: May 2019
Posts: 16
Rep Power: 5 
Hi guys,
I have to measure the temperature in a point between two semitransparent walls (glasses). The problem is that air (which is heated in a previous part of the model) passes through this point too, so I cannot say who impacts most at the vertex average value of T in this point. For example, let's say that in this point I measure 40 °C and let's say that 35°C are due to convection and 5°C are due to external radiation coming from the wall, so in this case I know that radiation contributed in "raising" only 5°C in this point. Does Fluent have a monitor like this? Can Fluent evaluate contributions separately? Or can I create anything like this? Gracias! 

May 15, 2020, 12:54 
Incident Radiation

#2 
Senior Member

__________________
Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. 

May 18, 2020, 02:58 

#3  
New Member
Josh
Join Date: May 2019
Posts: 16
Rep Power: 5 
Quote:
In that point I have an incident radiation of 3904.5 w/m2. So, if I understood correctly, I should try to: 3904.5 = 1 * 5.674 * 10^4 * T^4 where emissivity = 1 because I am between 2 glasses and nothing emits. So the value for T that I get (the positive one) is due only to radiation? Is this correct? 

May 18, 2020, 04:23 
Equation

#4 
Senior Member

Emissivity of 1 implies blackbody. For gray or real bodies, value is always less than 1. is 5.67e8 and not 5.67e4. And this will return absolute temperature.
__________________
Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. 

May 18, 2020, 04:35 

#5  
New Member
Josh
Join Date: May 2019
Posts: 16
Rep Power: 5 
Quote:
wall 1  point  wall 2 And the space between the walls is occupied by air. The point is not something real, I just place it in order to see the value of T in order to confront it with the value of T in points on wall 1 and wall 2. Plus, with this method, I do not seem to have a reliable number because the value of T is much higher if compared to the value of T over the surfaces of both walls. Thanks 

May 18, 2020, 04:44 
Temperature

#6 
Senior Member

Doesn't matter where the point is, the emissivity is always between 0 and 1. And in reality, while determining temperature from incident radiation, it is the absorptivity that is to be used and not emissivity, however, for most of the materials, both are assumed equal. If it is dry air, the absorptivity is very low. But 3.9 kW/sq.m. is a high flux and is supposed to give a high temperature.
__________________
Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. 

Tags 
radiation convection, report monitor, temperature average value, total temperature 
Thread Tools  Search this Thread 
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
whats the cause of error?  immortality  OpenFOAM Running, Solving & CFD  13  March 24, 2021 07:15 
Temperature floating point exception  ayckrom  FLUENT  1  May 13, 2015 09:02 
Calculation of the Governing Equations  Mihail  CFX  7  September 7, 2014 06:27 
is internalField(U) equivalent to zeroGradient?  immortality  OpenFOAM Running, Solving & CFD  7  March 29, 2013 01:27 
Free surface boudary conditions with SOLAVOF  Fan  Main CFD Forum  10  September 9, 2006 12:24 