Dear all, I do simulation on Ribbed tube but mesh in laminar flow. I get the warning from FLUENT 17 Divergence detected in AMG solver: pressure correction -> Turning off correction scaling! the details of parameters in below   Laminar flow (Velocity: 0.084193 m/s) •Working fluid: water liquid •Internal diameter tube=15.88 mm •Tube length =8.02 m (7.9 m is entrance region and 0.12 m is the test section) •Inlet Temperature = 27 C •Wall Temperature = 17 C •Reference Temperature = Film Temperature = 22 C •All Properties are calculated at Film Temperature I attached mesh. Thank you Best regards   enlarged meshmesh overview mesh quality