[serrar]

Hello, dear community,
To control the recirculation zone at a diverging channel, backward-facing step geometry. I used a synthetic jet where his position is in this stage. I found in publications that 30 periods were used for the blowing-suction of this jet and that I had also respected this condition. My problem is that in this publication, the synthetic jet takes only 0.1s so that the results converge around a gain of -24% over the distance, and that the average value of the attachment point for each period remains fixed as a function of time in the publication. Unlike my situation, I find that the response time is very late, close to 0.3 s and the gain exceeds -24%. I averaged the coefficient of friction after each period. - Do you have an idea to solve this problem? - What is the influence of frequency and time step on the point of attachment: turbulent flow separation - Is it a problem of the time step, mesh, the average coefficient of friction or something else? The simulation by ANSYS Fluent.
Mesh triangular in the domain, in the wall I used Y +.