need help on Prism Mesh Generation

Pete

Hello,

I have a problem while generating the prism layer around a tube with varying cross section (from round to rectangular). I put the natural size of 1 to catch up the sharp corner at the rectangular section.

I keep getting the pyramid elements (ie. the prism layer walk away and doesn't generate properly at the corner) at the corner of the rectangular end. Try to vary the parameter but still get the pyramid elements.

Can anyone please advise me on how to get rid of this problem? The quality of tet & tri elements are above 0.4. I can't really understand why it still not able to give a good prism mesh anyway.

Anyone know what does this message mean:

cannot insert this vertex (126860) into the volume dimension (2)

Thank you very much. Pete.

Part of the message from ICEM5:

extruding prism layer 5 first_t 16% first_t 33% first_t 50% first_t 66% first_t 83% first_t 100% 0 flat tetrahedra created between layers 0 pointy tetrahedra created between layers worst prism quality: 0.463019 worst pyramid quality: 0.631896 meshed layer 5 refining tetra-prism boundary cannot insert this vertex (126860) into the volume dimension (2) performing cleanup smoothing initializing element ratios beginning iteration worst TETRA_4 1.00688e-05 worst PYRA_5 0.0202051 smoothing 4455 TETRA_4's (up to 0.00444338) 30 PYRA_5's (up to 0.186641) 9201 vertices selected