Go to Post Sleep is for the weak - TEntwistle [more]
Home
Go Back   Chief Delphi > Other > Math and Science
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
 
 
Thread Tools Rating: Thread Rating: 4 votes, 5.00 average. Display Modes
Prev Previous Post   Next Post Next
  #16   Spotlight this post!  
Unread 19-09-2003, 00:12
patrickrd's Avatar
patrickrd patrickrd is offline
Registered User
AKA: Patrick Dingle
no team
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1999
Location: Medford, MA
Posts: 349
patrickrd is a splendid one to beholdpatrickrd is a splendid one to beholdpatrickrd is a splendid one to beholdpatrickrd is a splendid one to beholdpatrickrd is a splendid one to beholdpatrickrd is a splendid one to beholdpatrickrd is a splendid one to behold
Send a message via AIM to patrickrd
Quote:
Originally posted by Scott England
-d(a(du/dx))/dx+(d^2(b*(du^2/dx^2)/dx^2))+co*u+c1*(du/dt)+c2*(du^2/dt^2)=f(x,t)

this equation represents unsteady heat transfer in a fin
Actually, I think the c1*(du/dt) term is irrelevant. c1 will always be zero because the derivative is taken twice (with no intermediary steps in between) of the governing law (which is a function of t^2 only, not t), thus integration is guaranteed that the constant must equal zero. For comparison, consider an example of a sinusoid that is translated vertically in the y direction:

f(t) = sin(t) + 2

Then:

f'(t) = cos(t)
f''(t) = -sin(t)

Integrating twice yields:
f''(t) = sin(t) + C1t + C2

However, we are guaranteed that the sinusoid is translated, and should have no t term, thus C1 MUST be zero. With your above equation it's the same idea. c1 must be zero.

Seriously, putting aside my lame and incorrect argument above that has no validity at all, heat transfer equations (specifically fin analysis) are without any doubt in my mind the absolute worst equations I have ever come across. I'm actually impressed you found an equation for fins that is so simple... probably because it's in it's most generic form. Anyway, if you really like I can post the most obscene equation I can find in my heat transfer book. I remember it being very long, and containing many variables that took other equations to define what those variables mean, and so on and so on several times.

- Patrick
__________________
Systems Engineer - Kiva Systems, Woburn MA
Alumni, Former Mechanical Team Leader - Cornell University Robocup - 1999, 2000, 2002, 2003 World Champions
Founder - Team 639 - Ithaca High School / Cornell University
Alumni - Team 190 - Mass Academy / WPI
Reply With Quote
 


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Column Under Construction (2003 10-30) EddieMcD Chit-Chat 12 07-11-2003 20:14
What formulas can you use? Tton General Forum 7 04-11-2003 00:33
Image Discuss: Team 179's Crazy Critter CD47-Bot Robot Showcase 95 25-03-2003 08:08
crazy stuff chris144 Chit-Chat 19 08-04-2002 20:13
Logical statements or math formulas Manoel Programming 1 16-02-2002 23:29


All times are GMT -5. The time now is 22:01.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi