I am an engineering student in Germany and am currently working on my bachelor thesis. I want to generate a volume mesh but I keep getting an error. I don't know what exactly to change in my model but if I changed the meshing type to Tetrahedal the volume meshing worked. Unfortunately i have to use "Hexahedral or Prismatic" on that part of the model. I hope someone can help me here. Thanks in advance! 

Opera ​​​​​​​​​​​​​​