Andreas Koutras
Ansys Employee

Hello Ming,

The IGA developer provided the following answers.

Writing out the complete set of *IGA keywords is apparently not done in LSPP. I would try version 4.10 just to make sure it is not there. If it is missing there too, we will inform the developers and let them know about the issue.

1: The *LOAD_FACE_XYZ keyword is only meant to apply pressure on the entire surface of a (trimmed) shell. In contrast, the*LOAD_FACE_UVW keyword is meant to apply pressure on parametric faces (*IGA_FACE_UVW) comprised in the boundary representation (*IGA_2D_BREP) of a solid (*IGA_3D_NURBS_XYZ). 

In addition, the *LOAD_FACE_UVW keyword can be used to apply pressure on a partial surface of a (trimmed) shell or a solid. These parametric faces are not used in the definition of a shell discretization or of a solid's boundary description. Consequently, they should be defined separately, collected to a single set  (*SET_IGA_FACE_UVW), and the set ID should be referenced using FSID in Card 1 of either the *IGA_FACE_XYZ or the *IGA_VOLUMNE_XYZ keyword.

2:  Ideally, the pre-processor should take care of this. Development efforts are on the way in both LSPP and ANSA from BETA CAE.

3: The standard convention is applied, i.e. positive pressure is acting opposite to the surface normal vector.