<DOC>
<DOCNO>
1082
</DOCNO>
<TITLE>
the flow past pitot tube at low reynolds numbers, part 1-dash the numerical
solution of the navier-stokes equations for steady viscous
axisymmetric flow, part 2-dash the effects of viscosity and orifice
size on a pitot tube at low reynolds numbers .
</TITLE>
<AUTHOR>
lester, w.g.s.
</AUTHOR>
<BIBLIO>
o.u.e.l. no. 136, a.r.c. 22, 070, f.m. 2983 .
</BIBLIO>
<TEXT>
in this report numerical methods used to solve the navier-stokes equations
for steady viscous two-dimensional flow are extended to include
the case of axial symmetry . the equations and their finite difference
approximations are derived working in cylindrical polar co-ordinates
with the stokes' stream function and the vorticity as variables . a new
method of dealing with the boundary conditions is given .
the effects of viscosity and orlfice size on a blunt-nosed pitot tube
have been theoretically investigated up to a reynolds number of ten,
where the reynolds number has been based on the radius of the tube .
results are expressed in terms of a pressure coefficient where p is the
pressure measured in the tube, p the density of the fluid, and p  and u
the static pressure and velocity in an undisturbed flow at the position
of the tube .
the values of c for a blunt-nosed tube are found to be less than those
for tubes with hemispheroidal heads, but always greater than unity in
the range considered . the effect of the orifice size is to decrease c
as the orifice size increases, this decrease is very small but increases
 with the reynolds number . at a reynolds number of ten the decrease is
at most five per cent of the value of c when there is no orifice .
it is suggested that the decrease of c below unity found in some experimental
investigations at a higher reynolds number could be due to the
effects of orifice size .
</TEXT>
</DOC>
