! Thank you and Yes! I have checked the results of mass flow rate at the flux report, and it is correct value to my first applying on the inlet boundary. It is 0.504 kg/s, the same to what I assigned! But I am still curious about the velocity results. According to my calculation above, the results of velocity at the inlet should be 1.645 m/s, but the results of fluent is only 0.57 m/s. Can you guide me more? Thank You!n