# tutorial error?

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 April 28, 2000, 08:09 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

 April 29, 2000, 09:27 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?

 April 29, 2000, 11:33 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.

 April 29, 2000, 21:16 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.

 May 1, 2000, 12:49 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.

 May 1, 2000, 13:20 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.

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