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Moving-body models
available in CFD-FASTRAN are highly suited to simulate complex prescribed and
six-degree-of-freedom (6DOF) motions of rigid bodies. In many engineering
problems, this translates to multiple bodies moving relative to one another.
For example, moving control surfaces (canards, fins…) on a missile can be used
to maneuver the projectile towards its target. In such situations,
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The control surface has to move along with the missile
- It
would be preferable to specify the relative motion of control surfaces with
respect to the moving missile.
Such simulations can
be realized using CFD-FASTRAN’s motion model dependencies, the subject of this
note. If you have been curious, but never answered “yes” to the question “Is
this motion model dependent upon another motion model?” on the motion model
panel, then this note is for you.
The procedure to
setup model dependencies itself is very simple.
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For each component (missile, fin…),
create a separate overset grid system.
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After creating the motion models, from
the motion model that describes the relative motion, Select “yes” to the
question “Is this motion model dependent upon another motion model?”
- A
list of currently available motion models will be displayed. Choose the model
on which the current model will depend (The current model will be grayed out).
Figure 1. Setup
for motion model dependencies. Here, the prescribed motion
model for the
control surface (canard) is dependent on the missile body.
A
simple demonstration of this feature on a pitching airfoil with flap (Figure 2) can be found here.
Figure 2. Pitching
airfoil using model dependencies (click image for animation)
Relative
motion without model dependencies can also be specified in a prescribed motion
model directly as shown in Figure 3.
Figure 3. Setup
for relation motion without model dependencies.
Please visit our CFD
MODEL LIBRARY for other cases using these features.
If you have any
questions about this feature or would like us to discuss some other topic in
the future, please let us know.
Regards,
Abraham Meganathan
ESI CFD Support Team
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