- #1
Soren
- 10
- 0
The diffusion distance for a Brownian particle is given as x^2 = 2Dt
D: diffusion coeficient, t: time
However, not all textbooks include the factor 2 (i.e. they just write x^2=DT). Is there a difference or are they just beeing sloppy?
I run into trouble when I want to calculate the length of a channel required for mixing two fluids in a laminar flow based on the Péclet number
Simple explanation here: http://en.wikibooks.org/wiki/Microfluidics/Mixing
Here the time it takes for two fluids to mix (diffuse across the channel width) is only given as t = x^2/D
The factor 2 seems to be missing.
D: diffusion coeficient, t: time
However, not all textbooks include the factor 2 (i.e. they just write x^2=DT). Is there a difference or are they just beeing sloppy?
I run into trouble when I want to calculate the length of a channel required for mixing two fluids in a laminar flow based on the Péclet number
Simple explanation here: http://en.wikibooks.org/wiki/Microfluidics/Mixing
Here the time it takes for two fluids to mix (diffuse across the channel width) is only given as t = x^2/D
The factor 2 seems to be missing.