Fluid mechanics Reynolds number equation query

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SUMMARY

The discussion revolves around calculating the density of a fluid using the Reynolds number equation, specifically for a critical velocity of 2 m/s at Re=2000 in a pipe with a bore of 90 mm and a dynamic viscosity of 0.09 cP. The formula used is ρ = (Re * μ) / (Um * D), where ρ represents density, Re is the Reynolds number, μ is dynamic viscosity, Um is the velocity, and D is the diameter of the pipe. The participant consistently arrives at a density of 1 kg/m³, which is identified as unreasonably low, comparable to the density of air.

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smegal
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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

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


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


The Attempt at a Solution



\rho= (Re*\mu)/(Um*D)

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

Thanks.
 
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1 what? Units please :biggrin:

Also, why do you suspect 1 is wrong?
 
kg/m^3

That is a very low density.
 
smegal said:
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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