Generating surface from spline (error)
 

Hi,

I have the following problem in ICEM CFD. I have a certain geometry, built up from 6 different curves. I would like to make it 3D (with simple, normal extrusion, or copy in z-direction).

Create/Modify surface->Loft Surface over Several Curves
1) With the suction side of the airfoil, I recieved the following message:

2 curves
gk_cre_srf_loft_crvs GEOM srf.03 0.1 4 10 4 0 1
Error: {Large aspect number in GM90


2) With the top boundary, I recieved the following error message:

0 curves
2 curves
gk_cre_srf_loft_crvs GEOM srf.03 0.1 2 8 4 0 1
error processing E_180
proj bspline error: NaN's encountered in bspline
Error: {Unable to create surface in ProjLib
}

3) With the pressure side of the airfoil surface there was no problem.

4) With the straight lines of inlet and oulet of the airfoil surface there were no problems, neither.

When I tried to obtain the 3D geometry with sweeping, or connecting these curves as "simple surfaces", the resulting surfaces were different (or when I swept the surface, and defined the curves at the end of surface, there was a difference between the curves). I expected this difference to be only a graphical error (because of graphic card, RAM, etc), as I experienced similar phenomena with certain CAD-softwares earlier. But this was not the case in ICEM.

This caused for me a segmentation violation, negativ volume, etc. when I generated the mesh after block association, etc.

I think it can be a kind of problem, or bug with ICEM CFD handling of splines and generating surfaces from it. What I found strange, when I converted into unstructured mesh, and extruded it, the result was perfect (another problem how to define boundary conditions, surface on that mesh, or what to to with blocks there, how to associate if there is no surface, and why it converted the periodic bc-s into walls automatically, etc).

Regards,
TKE

p.s.: It is related somehow my earlier, "segmentation violation" thread as well.
http://www.cfd-online.com/Forums/ans...violation.html