[overture] Re: rigid body motion

  • From: Bill Henshaw <wdhenshaw@xxxxxxxxx>
  • To: overture@xxxxxxxxxxxxx
  • Date: Thu, 13 Aug 2015 14:33:39 -0400

Hi Junji,

The first thing to check is that the bodies move if there is no
constraint.
You may also want to increase the density to start with to avoid added mass
instabilities.

It is likely the constraint does not do what you think it does. You may
need to change
the formula for the constraint in RigidBodyMotion.C, function
applyConstraints.
I have not used constraints very much yet.

Regards,
Bill



On Thu, Aug 13, 2015 at 12:48 PM, Junji Huang <jhyt7@xxxxxxx> wrote:

Hi Bill,

I tried to set up a case of rigid body(two savonius blades) motion that is
constrained to rotate about a point being driven by freestream flow, the
commands for moving body is as follows:

specify grids to move
rigid body
density
1.
moments of inertia
0.1
initial centre of mass
0. 0.
initial angular velocity
0.
position is constrained to a line
0 0 1
done
bottom-savonius
top-savonius
done


For these settings, I want the top and bottom blades rotate about the
point (0., 0.). However, the blades didn't seem to move. I have checked the
torque using aero.C, it produced a negative value that should make the
blade rotate. Would you give me some suggestions on this kind of problem?
Thanks.

[image: Inline image 1]

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