[medaouarwalid]

hello every one, this is a nozzle called ''lobed nozzle'', it has a circular shape at the inlet and a corrugated shape at the exit, in my case, the area of the inlet is 314 mm² . the area of the exit is 213 mm² .
experimentally, the velocity at the center of the inlet area was 7.5 m/s and when i mesured the velocity at the center of the exit it was 4.5 !!!
numérically it was an other thing , when i set inlet velocity at 7.5 it gave me 10 m/s at the exit which i think is a logical result if we consider the continuity equation. now i don't know what to believe because i repeated the experimental many times and i get the same result each time. There is something wrong here but i didnt find it
noting that i used the ''SST K-omega'' model and i set the the walls of the nozzle as '' no slip WALL'' in BC