Erik Kostson
Ansys Employee
I never seen this - can you send us a link where this is done, and what you are doing - also, what buoyancy effects do you need in air?- if it is for water , then you should be looking at aqwa for that if one wants to study this on floating structure a bit accurately and detail.

As for the MESH200, one has say HEX20 SOILD186 everywhere on a 3D part, and we want to attach them (MESH200) to one face called ASU (face/surface named selection on 3D part):

/PREP7
ET,1000,200
KEYOPT,1000,1,7 ! QUAD8 needs to be used here since we have HEX20 SOLID186,
CMSEL,S,ASU,NODE
TYPE,1000
ESLN
ESURF
ALLSEL,ALL
/SOLU