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Fluid mechanics Reynolds number equation query

  • Thread starter smegal
  • Start date
  • #1
7
0
1.I have been asked to:

Calculate the density of a fluid if a ctitical velocity of 2m/s at Re=2000 in a pipe of bore 90mm at a dynamic viscosity oc 0.09cP

I have calcualted the variables to SI units and found

[tex]\rho[/tex]=?
Um (V) =2m/s
D=0.09m
[tex]\mu[/tex]=0.09X10^-3


I am rearranging this formula
http://www.rpgroup.caltech.edu/%7Enatsirt/aph162/webpages/F2WP2/reynoldsNumberFormula.png [Broken][/URL]


The Attempt at a Solution



[tex]\rho[/tex]= (Re*[tex]\mu[/tex])/(Um*D)

I keep getting 1 as the answer for the density. Have I converted something to SI units incorrectly?

Thanks.
 
Last edited by a moderator:

Answers and Replies

  • #2
diazona
Homework Helper
2,175
6
1 what? Units please :biggrin:

Also, why do you suspect 1 is wrong?
 
  • #3
7
0
kg/m^3

That is a very low density.
 
  • #4
Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
12,098
129
kg/m^3

That is a very low density.
That's comparable to air, which is 1.2 kg/m^3 under normal conditions (20 C, 1 atm)
 

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