Hi @Vinaykumar and sorry for the small delay.
The errors can be fixed as follows:
As we need a fluid and solid region we need all regions to be assigned to either a solid or fluid. An example can be found here: Heat Sink - Electronics Cooling
In the project you can also find a multi region mesh assignment but here is a (small) tutorial from the doc: Multi Region Mesh Tutorial
The warning just tells you that some faces are unassigned and need a boundary condition otherwise the default “no-slip” will be applied. So make sure everything is assigned properly.
P.S.: A common mistake is that the CAD has no overlapping faces at interfaces - that definitely needs to be done pre-processing wise. More details can be found in the multi-region mesh tutorial I posted under 2).
Hope that helps! If you have any further questions make sure to reach out either to our PowerUser @vgon_alves or me.
All the best!