×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Average temperature of a sphere

Average temperature of a sphere

Average temperature of a sphere

(OP)
Hello;

I made axisymmetric calculations and, among other things, found the temperature distribution in a sphere after an hour of heating. I need to estimate the average temperature of the entire sphere, how can I do it based on the node's temperature?

With much appreciation,
Sincerely,

John

RE: Average temperature of a sphere

Hi,
why not get the nodal results "TEMP" over all the nodes, and average them? winky smile
OK, I understand: you have unevenly-spaced nodes so that the arithmetic average does not necessarily reflects the "true" average temperature of the body. The simplest workaround, if you have 2D-axisymmetric model, is to build a mapped mesh with a regular pattern of nodes, evenly spaced. You can enhance the mesh regularity by imposing a certain number of divisions on the bounding lines of the quarter-of-circle. Please refer to the Help on the rules to follow in order to map-mesh a 3-sided area.

Regards

RE: Average temperature of a sphere

How about getting first the average temperature of each element by analyticallly averaging nodal temperatures.

Then calculating average volume temperature by sum(element temps x element volumes)/total volume

This way the locations with smaller elements and higher nodal density will have a smaller impact on the average temperature.

RE: Average temperature of a sphere

Made this routine in a few minutes.
It is not tested as I have no thermal model at hand.
Might need a little tweeking.


esel, [...]  !select relevant elements

cm,allelements,elem
eee=elnext(0)
vvv=0

*dowhile,eee
   esel,s,,,eee
   nsle
   teltemp=0
   nnn=ndnext(0)

   *dowhile,nnn
      teltemp=teltemp+temp(nnn)
      nnn=ndnext(nnn)
   *enddo

   *get,nonodes,node,0,count
   *get,vv,elem,nnn,volume

   aveltemp=teltemp/nonodes
   tovoltemp=aveltemp*vv
   vvv=vvv+vv

   esel,s,,,allelelments
   eee=elnext(eee)
*enddo

avtemp=tovoltemp/vvv   !here is your average body temp


 

RE: Average temperature of a sphere

(OP)
Thank you very much.

cbrn: that's what I tried first, but the answer I've got doesn't look right

eelco71: I'll try to implement this today.

Sincerely,

John

RE: Average temperature of a sphere

Hello,

I think, the average temperature is the temperature of the sphere after a very long time in an adiabatic state of the sphere. In this case the sphere will aim an uniform temperature, and this will be the average temperature. Of course you will have to simulate this for a few steps more, but it would be a very good way to check the accuracy of other methods discussed here.

Regards
Alex

RE: Average temperature of a sphere

Indeed Alex,
and should also be equal to time*power*mass*C.

I just realised: a transient thermo-elastic-plastic sphere,
with temperature dependant C,KXX,ALPX,EX,KINH, very intresting.

Grab every opertunity you have to check your results.
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources