Re: Need Help: Fluid Dynamics Question

I am talking about the water and air under room temperature. I would like to
know how faster air flows than water through the same hole at the same room
temperature. I searched on the Internet. Some says that air flows 50 percent
faster than water. I am not sure that information is correct or not.

JS


"Ed Ruf" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> On Sat, 13 Sep 2003 22:02:28 -0400, in sci.mech.fluids "John Smith"
> <[EMAIL PROTECTED]> wrote:
>
> >Hi, can anybody answer the following question? Thanks.
> >
> >Under the same pressure and through the same size of a hole, which of
these
> >two: air and water, flows faster? Does it have something to do with the
size
> >of the hole (0.01 mm, 1 mm, or 10 mm),  the thickness of the hole (0.01
> >mm, 1 mm, or 5 mm), or the pressure?
>
> When you say water, are you implicitly implying liquid water? If both are
a
> gas, then the answer may be unintuitive.
>
> If air vs. water vapor and the pressure ratio across the hole is enough
for
> choked flow:
>
> Gamma for water vapor is slightly less than that of air at 70F, 1.37 vs.
> 1.4. R for water vapor is 455 J-kg/K vs 287 for air.
>
> The sonic velocity ratio of air to water vapor for the same temperature is
> then
> sqrt( R_air x gamma_air_ /R_wv x gamma_wv)
>
> or  sqrt ( 287 x 1.4 / 455 x 1.37) = 0.64,
>
> So in the case of choked (sonic) flow the velocity of water vapor is
higher
> than that of air.
>