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

tutorial error?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 28, 2000, 08:09
Default tutorial error?
  #1
K.L.Huang
Guest
 
Posts: n/a
in the tut2.2 air inlet v=10m/s

A=0.0254m *0.0254m

Q=6.4516e-3 m3

solid particle

q=0.01% * Q =6.4516 e-7 m3/s

diameter =4e-5 m

volume =3.35103e-14 m3

that is, particle number 19,252,575.58 per second

but in the tutorial 2.2 write 1,925,257.56 per second

I think there must be something wrong? anybody can tell me?

K.L.Huang

  Reply With Quote

Old   April 29, 2000, 09:27
Default Re: tutorial error?
  #2
John C. Chien
Guest
 
Posts: n/a
(1). I can only say that both numbers were not computed by the computer. It is more likely that those are calculated by hand using electronic calculators. (2). Why not write a simple Fortran program and check the result again. What do you mean by .58 particle number per second? How do you count it?
  Reply With Quote

Old   April 29, 2000, 11:33
Default Re: tutorial error?
  #3
K.L.Huang
Guest
 
Posts: n/a
i dont mean the .56 or .58 i mean that the particle flow rate should 10 times the number mentioned in the tut book.
  Reply With Quote

Old   April 29, 2000, 21:16
Default Re: tutorial error?
  #4
John C. Chien
Guest
 
Posts: n/a
(1). Q=6.4516E-07 (2). volume=3.35103E-14 (3).Q/volume=(6.4516/3.35103)E+07=1.925258801E+07=19252588.01 (4). If Q/volume=19252575.58, and Q=6.4516E-07, then volume=(6.4516E-07)/(19252575.58)=(6.4516/1.925257558)E-14=3.351032164E-14 (5). If volume=(4/3)pi(rxrxr)=(4/3)pi(2x2x2)E-15=(32pi/3)E-15=33.51032164E-15 (6). Which means, if we use the volume stated in the message, Q/volume should be 19252588.01. And both Q/volume numbers quoted in the message are incorrect.(these are 19252575.58 and 1925257.56) (7). Since my volume of the particle is 33.51032164E-15 which is different from the stated volume of 3.35103E-14, one can only say that the stated volume is incorrect. (8). Now we have shown that the volume, the two Q/volume numbers are all incorrect. (9). The correct Q/volume is 1.925257558E+07, but only if the correct volume of 33.51032164E-15 is used. (10). So much for the simple math.
  Reply With Quote

Old   May 1, 2000, 12:49
Default Re: tutorial error?
  #5
K.L.Huang
Guest
 
Posts: n/a
(1). Q=6.4516E-07 (2). Volume=3.35103E-14 (3). Q/volume=(6.4516/3.35103)E+07

=1.925258801E+07

=19252588.01 (4). If Q/volume=19252575.58, and Q=6.4516E-07,

then volume=(6.4516E-07)/(19252575.58)

=(6.4516/1.925257558)E-14

=3.351032164E-14 (5). If volume=(4/3)pi(rxrxr)

=(4/3)pi(2x2x2)E-15

=(32pi/3)E-15=33.51032164E-15 (6). Which means, if we use the volume stated in the message,

Q/volume should be 19252588.01.

And both Q/volume numbers quoted in the message are incorrect.

(these are 19252575.58 and 1925257.56) (7). Since my volume of the particle is 33.51032164E-15

which is different from the stated volume of 3.35103E-14,

one can only say that the stated volume is incorrect. (8). Now we have shown that the volume,

the two Q/volume numbers are all incorrect. (9). The correct Q/volume is 1.925257558E+07,

but only if the correct volume of 33.51032164E-15 is used. (10).So much for the simple math.

-------------------------------------------------------------------------------- Mr.Chien

Thanks very much for your detail calculation of my question. But I think you really mis-understand my original question. To me , it is a physical problem, not a math or numerical problem. I think Q/volume=19252588.01 (item3)

=19252575.58 (item4)

=19252588.01 (item5 first one)

=19252575.58 (item5 second one) But not equal to 1925257.56 (item5 one and the tut2.2 one) Do'nt you notice that there is a difference of one order(10^1). This makes the calculated particle flow rate in the modle is only 1/10 of real flow rate. Understand? I agree with your opnion in item 10, "So much for the simple math". But it is physical not a math problem.

  Reply With Quote

Old   May 1, 2000, 13:20
Default Re: tutorial error?
  #6
John C. Chien
Guest
 
Posts: n/a
(1). I think I understand your question. (2). I just don't want to say that your number is less incorrect than their numbers. (3). It is quite obvious that the decimal point is misplaced. So, their number is incorrect by a factor of ten.
  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
CFX Error in Tutorial 21 Vidiii CFX 4 May 2, 2009 14:18
Error in bc.c for VOF tutorial? hungpavn FLUENT 1 December 30, 2006 14:07
Error occuring in pro-am first tutorial aero CD-adapco 2 December 21, 2006 09:58
CEL error in tutorial #20 Anurag CFX 1 January 21, 2005 17:23
Error Tutorial 7 ? Mathew CD-adapco 2 July 20, 2000 19:35


All times are GMT -4. The time now is 12:20.