Graphics Reference
In-Depth Information
Ketchup 1 × 10
-1
(0.1)
Melting glass 1 × 10
0
(1)
Stickiness
In addition to setting viscosity, you can set the degree to which the fluid sticks to a surface or slips off the
surface. This is done using the Domain Boundary tab. Of course, this produces only an approximation of the
behavior of real fluids. In reality, all fluid sticks to surfaces at the molecular level, but to the naked eye, fluids
such as water appear to slide right off certain surfaces. Because the fluid simulator operates at resolutions much
lowerthanmolecularscale,itisunconvincingtohavefluidssuchaswaterappeartosticktosurfaces.Forfluids
that should not appear sticky or gluey, select Free Slip from the Slip Type drop-down menu. No Slip will cause
the fluid to stick to surfaces, and Partial Slip will set slippage according to the values you enter in the panel's
fields. You can set these options on individual obstacles as well.
Compressibility
Another quality of fluids that can be represented in Blender is
compressibility
. This is the degree to which the
fluid shrinks in size orcompresses under pressure. Innature, all fluids are very slightly compressible, but this is
too slight to be noticeable at the scales that animators usually want to work with. In fact, the El'Beem simulat-
or can work much faster if the fluid is considered to be slightly more compressible than it would be in nature,
which is why this parameter exists. If you find that your fluid seems overly bouncy or elastic, you may want to
consider lowering the compressibility.
Inflow and Outflow
When you use a Fluid object, the amount and initial location of the fluid introduced to the domain are determ-
ined by that object when the simulation begins. Animating the location or scale of a Fluid object will have no
effect on the behavior of the fluid after the fluid has been generated. This is suitable for situations in which the
amount of fluid you want to deal with is static, such as a sink full of water, but in cases where you want to
introduce fluid to or remove fluid from the scene over time (such as an open tap or an unplugged drain), it is
necessary to use Inflow and Outflow objects.
Inflow
Using an Inflow object enables you to produce a steady stream of fluid into the simulation.
For a quick example, fire up a fresh session of Blender and do the following:
1.
In the top view (NUM7), add a disk-shaped mesh by pressing the spacebar and choosing Add > Mesh
> Circle. Add the circle with the parameters shown in
Figure 7-14
.
Make sure that Fill is selected.
