Hi Bill,
In OverBlown v21, the code RigidBodyMotion.C had the following lines
to compute the angular acceleration from the torque as :
for( axis=0; axis<3; axis++ )
{
omegaDot(axis)=(
(1.-alpha)*(
g(0,ip1)*e(0,axis,ip1)
+g(1,ip1)*e(1,axis,ip1)
+g(2,ip1)*e(2,axis,ip1))
+alpha *(
g(0,i)*e(0,axis,i)
+g(1,i)*e(1,axis,i)
+g(2,i)*e(2,axis,i))
)/mI(axis);
}
/So this is equivalent to the statement G dot e_i = mI_i
\omegaDot_i (From Newtons Laws). /
whereas in cg.v22, the same code is as follows :
for( axis=0; axis<3; axis++ )
{
const int axisp1=(axis+1) % 3;
const int axisp2=(axis+2) % 3;
omegaDot(axis)=(
(1.-alpha)*(
(mI(axisp1)-mI(axisp2))*w(axisp1,ip1)*w(axisp2,ip1)+
g(0,ip1)*e(0,axis,ip1)+
g(1,ip1)*e(1,axis,ip1)+
g(2,ip1)*e(2,axis,ip1))
+alpha *(
(mI(axisp1)-mI(axisp2))*w(axisp1,i)*w(axisp2,i)+
g(0,i)*e(0,axis,i)+
g(1,i)*e(1,axis,i)+
g(2,i)*e(2,axis,i))
)/mI(axis);
}
Now, both versions look alike except for the additional term in
cg.v22 - " (mI(axisp1)-mI(axisp2))*w(axisp1,ip1)*w(axisp2,ip1) " ~
(I2-I3)*w2*w3 ..
I'd like to know the basis for adding this term...
Regards,
Dominic
