Our project is simulation of dam flooding on terrain. The terrain is generated in terrain preparation. It was closed with a surface for the simulation in fluid scenario creation, but showing error while meshing. As shown in the image it is showing error of region 3 also which is not defined by me. It might also be due to terrain being a actual data and surface is polyhedral data, how do I convert terrain data to polyhedral data...? 

Edu ​​​​​​​3DEXPERIENCE ​​​​​​​SIMULIA ​​​​​​​Fluid Model Creation ​​​​​​​