[ingraban]

I try to do a simulation of a fire in a tunnel with longitudinal air flow.
- OpenFoam Version v1812
- fireFoam case based on tutorial smallPoolFire3D

- The BCs at the inlet portal are
u: flowRateInletVelocity
p: calculated
p_rgh: prghTotalHydrostaticPressure
ph_rgh: fixedFluxPressure

- The BCs at the outlet portal are
u: pressureInletOutletVelocity
p: calculated
p_rhg: prghTotalHydrostaticPressure
ph_rgh: fixedValue

- The BCs at the tunnel walls are
u: noSlip
p: zeroGradient
p_rgh: fixedFluxPressure;
ph_rgh: fixedFluxPressure;

- The fire is defined similarly to the inlet portal, just giving a mass flow rate of CH4.

The setup works fine without the fire (giving a mass flow rate of air instead of CH4) and with a CH4 fire, but with zero flow rate at the inlet portal. I tried multiple variations of simple and derived boundary conditions for pressure and velocity.

With the fire and the air flow, the fire appears to affect the inlet condition. The longitudinal flow is not as defined in the BC. The visualisation of the flow velocity shows peaks close to the BC. The picture shows a longitudinal section though the domain, close to the inlet BC. We are looking at Ux (should be evenly distributed across the inlet). What am I doing wrong?