[elochana]

Dear collegues,

Bascially it's a short tube which has a fan blowing in from one end and an HVAC diffuser fitted at the other end (There is a little obstacle inside the tube around which the air flows. But you can forget about it for the moment). A huge re-circulation bubble is generated just below the diffuser and the flow is sucked back into it rather than getting diverged as expected. Is this normal. I can understand the existance of the re-circulation bubble, but a normal diffuser should diverge the air flow, but it seems this is not the case. Pls. help.

Details of the simulation:
Ansys fluent
Models: k-epsilon realizable with default values (k-epsilon standard was also used with similar results on the above issue)
BCs: Fan outlet (exhaust into the tube) -> velocity inlet
Fan inlet -> Pressure outlet. ('Fan-intake' BC was also used with similar results on the above issue)

Thank you