The design of fluids management processes in the low-gravity environment
of space
requires an accurate description of capillarity-controlled flow in containers.
Here we
consider the spontaneous redistribution of fluid along an interior corner
of a container
due to capillary forces. The analytical portion of the work presents an
asymptotic
formulation in the limit of a slender fluid column, slight surface curvature
along the flow
direction z, small inertia, and low gravity. The scaling introduced
explicitly accounts
for much of the variation of flow resistance due to geometry and so the
effects of
corner geometry can be distinguished from those of surface curvature. For
the special
cases of a constant height boundary condition and a constant flow condition,
the
similarity solutions yield that the length of the fluid column increases
as
t1/2 and t3/5,
respectively. In the experimental portion of the work, measurements from
a 2.2 s drop
tower are reported. An extensive data set, collected over a previously
unexplored range
of flow parameters, includes estimates of repeatability and accuracy, the
role of inertia
and column slenderness, and the effects of corner angle, container geometry,
and fluid
properties. At short times, the fluid is governed by inertia
(t[lsim ]tLc).
Afterwards, an
intermediate regime
(tLc[lsim ]t[lsim ]
tH) can be shown to be modelled by a constant-flow-like
similarity
solution. For t[ges ]tH it is found
that there exists a location zH at which
the interface height remains constant at a value
h(zH, t)=H which
can be shown
to be well predicted. Comprehensive comparison is made between the analysis
and
measurements using the constant height boundary condition. As time increases,
it is
found that the constant height similarity solution describes the flow over
a lengthening
interval which extends from the origin to the invariant tip solution. For
t[Gt ]tH, the
constant height solution describes the entire flow domain. A formulation
applicable
throughout the container (not just in corners) is presented in the limit
of long times.
Smart Distance Lab Art Fair - An experimental data set on social distancing during the COVID-19 pandemic
