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Introduction
This example describes the operation of a drug delivery system
that supplies
a variable
concentration of a water soluble drug. A droplet with a xed
volume of water
travels
down a capillary tube at a constant velocity. Part of the
capillary wall consists
of a
permeable membrane separating the interior of the capillary from
a
concentrated
solution of the drug. As the drop passes by the membrane, the
drug dissolves
into the
water. To model this process a constant ux of the drug is
assumed on the
capillary
wall for the duration of its contact with the membrane. By
altering the droplet
velocity,
the nal concentration of the drug in the drop can be
adusted.
WORKING
!n the "odel #i$ard window, clic% the &' Axisymmetric
button.
& !n the (elect Physics tree, select )luid )low*"ultiphase
)low*Two+Phase)low, "oving
"esh*aminar Two+Phase )low, "oving "esh -tpfmm.
/ 0lic% the Add button.
1 0lic% the (tudy button.
2 !n the tree, select Preset (tudies*Time 'ependent.
3 0lic% the 'one button.
GEOMETRY
!mport the model geometry.
4 !n the "odel Builder window, under 0omponent 4 clic% 5eometry
4.
& !n the 5eometry settings window, locate the 6nits
section.
/ )rom the ength unit list, choose mm.
Import
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4 7n the 8ome toolbar, clic% !mport.
& !n the !mport settings window, locate the !mport
section.
/ 0lic% the Browse button.
1 Browse to the model9s "odel ibrary folder and double+clic% the
le
drug:delivery:mm.mphbin.
2 0lic% the !mport button.
DEFINITION
"odel 'enition
The droplet is visible near the top of the geometry. The
hori$ontal lines
across the capillary are included to assist with meshing.
The drop is initially stationary at the top of the domain, but
accelerates
rapidly to a constant velocity before it reaches the permeable
membrane.
The
permeable part of the capillary is not visible as part of the
geometry as it is
represented
by a function applied to the boundary condition. !t is located
between $;
