Hey Zhang,
Yes, the get_normals() function will return the outward
normal vectors.
You had mentioned that force on the airfoil was given by:
\vec{F}=\sum_{qpface_bound} {\tau*normal -normal*p_{qp}}
*Jxw_face_bound[qp] . Should that be a \tau*normal + normal*p_{qp}} ?
Thanks.
On Sun, Apr 26, 2015 at 11:07 PM, Zhang <[email protected]> wrote:
> I just made some correction, say, since pressure is defined in a space one
> order
> lower than velocity. In the last code I put all quadrature computation in
> velocity space by mistake,
> now I put the two integrals, $\int \tau * normal$ and $\int (-p)*normal$,
> into two separate
> sections and finally add their partial integral together.
>
> Here are the comparison (for only pressure forces)
> 1) np=1 // the old one
> step 9, forces: (-1.299297e-01 3.460514e-03 0.000000e+00 )
> step 9, moments: (0.000000e+00 0.000000e+00 7.266930e-05 )
> 2) np=1 // the corrected one
> step 9, forces: (-1.799026e-01 -3.255020e-06 0.000000e+00 )
> step 9, moments: (0.000000e+00 0.000000e+00 -9.115135e-07 )
> 3) np=4 // the corrected one
> step 9, forces: (-1.799026e-01 2.098503e-06 0.000000e+00 )
> step 9, moments: (0.000000e+00 0.000000e+00 5.020619e-07 )
>
> when AOA=0.0 degree, the lift and z-pitching moment are dramatically
> reduced to zero.
>
> Now the question is the negative x-force. In the face quadrature, does
> fe_pres_face->get_normals()
> return all outward normal vector?
>
> Zhenyu
>
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--
Vikram Garg
Postdoctoral Associate
Predictive Engineering and Computational Science (PECOS)
The University of Texas at Austin
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