I'm a chemistry major applying to grad schools in chemical engineering and I'm interested in studying combustion and fluid dynamics. I'm interested in how engines and the chemical reactions that fuel them work however those are all areas of research done by Mechanical Engineering departments. Is there anyway to do an interdepartmental PhD thesis or somehow transition from ChemE to MechE after the degree? I'm thinking about applying directly to the MechE departments but I just don't think I have the physics background since I'm a chem major. I only have 2 semesters of intro physics but I do have math through Diff Eq. and one intro ChemE class (I will hopefully take another in the Spring). I'm applying to ChemE because from what I understand its a versatile degree and they can do anything.