[Daaman]

Hi,

I am planning on using the FFD_TWIST for deforming the geometry of my problem setup. In the configuration template, the following set of parameters are used in the definition of FFD_TWIST for shape deformation.

- FFD_TWIST ( FFD_BoxTag, j_Ind, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )

I am interested in knowing the meaning of the parameters listed above, but couldn't find it. Is there any explicit definition available for the above parameters, or maybe an example test case where FFD_TWIST has been implemented? Also, is DV_VALUE specified in degrees?

Thanks for the help!

[pcg]

Hi,

The x y z parameters define the twist axis.
j_Ind is the index of (presumably) a spanwise section of the wing, i.e. a section that is intersected by the twist axis.
The origin of the twist is the intersection, and the twist is around the y axis (no other axis can be used).
The twist angle is given by atan(DV_VALUE / Ref Length), that is, the value you give is a distance.
According to the code, this is done because:

/*--- The angle of rotation is computed based on a characteristic length of the wing,
otherwise it is difficult to compare with other length based design variables. ---*/

[Daaman]

Thanks for the detailed answer Pedro!