thank you for your answer. n-I chose a density based solver because it's a compressible fluid with density change; nWhat do you mean by the Mach number of flow (I'm still an apprentice in fluid mechanics I don't master all the notions yet) -n-Yes I created a dynamic mesh in the modeln-the quality of my mesh : nThe max skewness is 0.84 nThe min orthogonality : 0.15 n