CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > CFX

Choosing the right monitor points

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   February 16, 2011, 14:30
Default Choosing the right monitor points
  #1
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Being a newbie to CFD, I lack the proper understanding in identifying the quantities of interest to be monitored while a run is in progress. I mean I’m not clear with identifying the right quantities in a CFD analysis which tend to be really crucial that their variation needs to be monitored while the run is in progress to judge the reliability of the convergence obtained.

Can some one please suggest me upon this by quoting the instances of some typical CFD problems. As of now I’m working upon the cfd analysis of hot air flow in a cooking oven. For this problem i'm considering quantities like volumeAve(Temperature)@FLUID , massFlowAve(Temperature)@Trays to monitor.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   February 16, 2011, 17:11
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,823
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
The purpose of CFD is to conduct a numerical experiment. So in your experimental model what parameters are of interest that you would like to measure? This is why you need to define WHY you are doing the model before you start anything. After you know why you are doing a model the important parameters should be apparent.

So WHY are you modelling the oven? Are you checking for temperature unevenness? Or finding out how hot the outer surface gets? Or seeing how fast a roast turkey cooks inside? Each of these purposes would demand different outputs.
ghorrocks is offline   Reply With Quote

Old   February 17, 2011, 00:00
Default
  #3
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Ok, if the case is like I'm interested in knowing how fast the oven cooks the chicken grill and considering some other case of an electronics cooling problem where in I'm interested to know the rate of heat dissipation from a IC chip into it's surroundings.

So for these cases can you please suggest me upon the monitor points to choose.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   February 17, 2011, 22:14
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,823
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Then put a temperature monitor point in your chook and a temperature monitor point on your IC.
ghorrocks is offline   Reply With Quote

Old   February 18, 2011, 00:42
Default
  #5
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Can you please tell me when to use a point and when to use an expression to monitor the quantities of interest in the simulation. I mean if i'm interested in knowing the rate of heat dissipation from the IC chip. Then should I use a point on the IC chip surface to monitor the temperature (or) do I need to go with something like: areaAve(Temperature)@ICchip.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   February 18, 2011, 07:10
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,823
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Really the issue is about engineering judgement. You need to decide what is the best way to report the result.
ghorrocks is offline   Reply With Quote

Old   February 24, 2011, 00:22
Default
  #7
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Glenn, in the electronics cooling problem I was referring to, some surfaces of the ICchip are Fluid solid interfaces and the others form Solid Solid interfaces sol if i'm interested in monitoring the area averaged Temperature for the whole ICchip , then how do you suggest me to proceed ?
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   February 24, 2011, 20:15
Default
  #8
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,823
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Then calculate the areaAve(T)@surface - isn't that obvious?
ghorrocks is offline   Reply With Quote

Old   February 25, 2011, 02:34
Default
  #9
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
ok ill try it that way
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   February 26, 2011, 05:44
Default
  #10
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Can I use the expression areaAve(Wall Heat Flux), to monitor the area averaged heat flux at an interface( fluid-solid (or) solid-solid) (or) is it confined to monitor heat flux on a wall.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Old   March 1, 2011, 01:17
Default
  #11
Senior Member
 
---------
Join Date: Oct 2010
Posts: 302
Rep Power: 8
saisanthoshm88 is on a distinguished road
Well, I checked it out and I found that areaAve(Wall Heat Flux) can be applied to sides of the interfaces also rather than to wall boundary type alone.
__________________
Best regards,
Santhosh.
saisanthoshm88 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Please guide me for choosing between FEM and Lattice Boltzmann gholamghar Main CFD Forum 1 February 19, 2010 06:38
Phase choosing in Volume of Fluid Method Gitesh P Main CFD Forum 3 January 28, 2010 11:57
choosing faces in CFX with imported WB mesh mactech001 CFX 1 December 7, 2009 03:30
Choosing the right timestep shangzung OpenFOAM 2 October 29, 2009 03:58
Choosing a Company name Z Hashmi Main CFD Forum 2 August 19, 2006 14:30


All times are GMT -4. The time now is 15:00.