Connect two fluid zones in hydrogen dispersion modeling
 

Hello
I'm new to Ansys fluent and I have been struggling for a while with this.
My task is to assess the safety of hydrogen diffusion in cars during accidental leakage as described in Fig. 1 below. The hydrogen leaks from the orifice to the car compartment and exhausts through the sunroof. I tried to use Boolean in the design modeler to subtract the hydro tank from a car. I also set the car geometry to wall. I do nothing with the diffusion domain and car. But it seems to be wrong cause the result shows that the streamline of air inlet goes through the car geometry and the hydrogen stream does not go out of the car Fig 2. I read some posts and interface/ mesh contact may be the best solution but I don't know to to set up them. Can anyone tell me what should I do to correct this task?
Thanks in advance for the help ^^

Fig 1: https://drive.google.com/file/d/12ms...ew?usp=sharing
Fig 2: https://drive.google.com/file/d/1zrc...ew?usp=sharing