This is the common problem people face, there may be some miss allignments in the joints, which will give your exact extruded surface but that hits up only during meshing.
it is a probleme related with the generation of an external fluid domain. so i have to create new part to have the couplage between the fluid domain and the solid domain
OK then while creating model make these objects as frozen and then make connection between them. Thus mesh at the joints of fluid and solid zone will have connectivity. I think this will help you.
This is the common problem people face, there may be some miss allignments in the joints, which will give your exact extruded surface but that hits up only during meshing.