: Choose from the Simulate toolbar, from the other toolbars, or from the Hair toolbar.
: Select the drag object and press Enter.
The Drag forces opposes the motion of ICE particles, rigid bodies, or hair going through a fluid, and depends on the flow
of the fluid around the object.
Drag has no effect on Soft body or Cloth simulations.
For more information on forces in general, see Forces [ Simulation].
To use this force in an ICE tree, see Creating and Applying ICE Forces to ICE Simulations [ICE Fundamentals].
Length of the arrow is determined by the Amplitude value.
The basic drag force () formula is:
Fd = 0.5 * Cd * rf * A * v≤
where:
Cd is the coefficient of drag
rf is the density of the fluid
A is the cross-sectional area of the object
v is the object velocity relative to the fluid velocity
is not a constant but instead depends on the value of a dimensionless constant called the Reynold's number (). is a ratio between the inertial property of the fluid that is being pushed out of the way by the object and the viscous drag
on the object.
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The name of the force.
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Toggles on/off the force.
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Strength of the drag effect. The parameter is a simple strength multiplier, which is the result of .
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You can set the flow type to be either Laminar or Turbulent. A turbulent drag is usually stronger than a Laminar one, but
depending on the values you use for the drag force, there may be no discernible difference between these two flow types.
Laminar flow is used when < , viscosity dominates and is inversely proportional to , hence ; therefore, is proportional to .
Turbulent flow is used when = , the inertial reaction becomes dominant and is very nearly constant; therefore, is proportional to .
The point at which fluids change their behavior from Laminar to turbulent is the Reynolds number.
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Determines the area used to compute the drag effect on the simulated objects. The basic drag force formula uses the cross-sectional area of the simulated object ( option) as the scaling factor.
If the option is on, you can also set the value, which is in Softimage units. This calculates the drag effect using a specific radius around the simulated object.
If Assume Size is selected, then DragForce.Area = PI*(Drag.Radius^2)
If it's not selected, then DragForce.Area =PI*(Point.Size^2)
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