DPM and High speed air flow
 

I am a beginner of the Fluent. Now I am using Fluent to simulate a water injection in a high speed unsteady flow field. I meet a huge problem. When the interaction option was turned on, the temperature and velocity goes to unbelievable values. Some reach the limit values.

I check the grid, which is fine for the high speed flow. But the DPM model asks for the coarser grid. How can I set the case correctly when the Fluent is used to my simulation? Can anyone help me?

Thanks a lot!