jet preferred mode

Xu Zhou

Dear All,

I am confused with the "jet preferred mode instability" and "shear-layer instability". Does the Strouhal number of the shear-layer instbility is dependent on the roll-up of vortex structures with fundermental frequency, while the Strouhal number of the jet preferred mode is decided by the pairing process, which is half of the former one?

Can we obtain the value of the most amplified frequency only with "white noise"?

If the jet is forced at an arbitrary frequency of St=0.4, can we obtain the most amplified frequency St=0.3 at the end of potential core? If so, does it mean the imposed frequency is surpassed?

Best Regards,

xu Zhou