# Re: [APD] Re: Bubbles? -- or - Some hard topics not adding up!

```On Thu, 2004-02-05 at 07:02, David Terrell wrote:
> You know, I think I just need a refresher geometry class, UGH!  Volume
> isn't increasing by 2Pi :-(  The circumference does!  I'll do some quick
> math.  r is the old radius, R is the new radius (R=2r).  So, if
> v=Pi*r^2, and R=2r, then dv=Pi*4!  HAH, that means a 1.5" pipe has
> ~12.57 times more volume then a 0.75" pipe of the same length.  Now I'm
> really starting to think this thing will work ;-)  Man, someone stop me
> if I'm wrong!
>
> -Dave T. (mumbling to himself, 'a^2+b^2=c^2, garblegarblegarble')

um, doubling the diameter should quadruple the area (divide the flow by
4 in the case of your reactor assuming that your flow rate is limited
by tubing elsewhere in the system)

Area1=Pi*r^2
Area2=Pi*(2*r)^2
=Pi* 2^2 * r^2
Area2/Area1=4, not 4*pi

--
Andrew Mitchell <andrew at andrewmitchell_id.au>

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