Dear Fluent Users, Can anybody tell me how to handle the mixed water/air flow in an eductor. High speed water jet is being used to suck air at atmospheric pressure, i.e. there are 2 inlets, one for air, and the other for motive fluid water. At the outlet we have a mixture of air and water. Shall I use the Discrete Phase Modeling or the Multiphase Flow Model ? If the Multiphase Flow Model is to be used, which model must be employed ? The VOF Model, the Cavitation Model or the Algebraic Slip Mixture Model ? Any comments will be highly appreciated. Thanks. Hbet

Hello

Actually it depends on the physical situation. If the entrained air enters as bubbles then either ASMM or Eulerian multiphase models would be fine. The particle relaxation time of the air bubbles is fairly low (wrt to residence time scales) and ASMM should perform well. I wouldn't recommend VOF for a "mixed" outlet and also in the domain where the phases may not be stratified. Hope this helps.

- Jay

Hi !

Thanks for your interest.

Actually water enters the eductor free from air bubbles and due to high speed gained in the nozzle the pressure drops and pure air is sucked into the eductor, ie. at air suction boundary air volume fraction is 100%. Then they mix and leave the eductor as water-air mixture.

Do you still suggest using the ASMM or Eulerian multiphase models ?

Thanking you in advance.

Best regards,

Hbet