[shaonme]

I am trying to simulate a mixing process of Helium jet in atmospheric air. He is coming out from a tube of 4.6 mm inner dia with a Re number of 2500 where the air is considered stagnant.
To set the model, I use an inlet velocity BC with a velocity of 66.5 m/s for He jet inflow in the domain. I also set a zero pressure outlet BC at a sufficient distance from the inlet to allow enough space for mixing.
The model is in a steady state. To capture the mixing, I use the species transport model available in Fluent. It looks like the model works fine.
However, I found the velocity goes unexpectedly high (~1200 m/s max) in the domain when the solution is converged.
If anyone has any suggestions, it would be highly appreciated.