Boundary conditions in chtMultiRegionSimpleFoam
 

Hi All, I have a problem and I can't solve it by myself
Maybe it's not a big problem, but I am a amateur in OpenFOAM

I have a simple system: a solid rod in the centre and a water flow outside it, I calculated this system with other thermohydraulics codes (NOT CFD) and there I use simple boundary conditions:
inlet - water velocity
outlet - water pressure
And it works!

But here I can't run the simulation without inlet pressure condition, and p and p_rgh conditions are connected strongly. I use ZeroGradient conditions, but I don't suggest that these conditions are correct.
Can I simulate it without some conditions?