Non-modal disturbances growth in a viscous mixing layer flow

摘要: The non-modal transient growth of disturbances in an isothermal viscous mixing layer flow is studied for Reynolds numbers varying from 100 up to 5000 at different streamwise and spanwise wavenumbers. It found that the largest takes place wavenumbers which stable. In linearly unstable configurations, can only slightly exceed exponential short times. Contrarily fastest growth, two-dimensional, most profound attained by oblique three–dimensional waves propagating angle with respect base flow. By comparing results several mathematical approaches, it concluded within considered model a tanh velocity profile, optimal governed eigenvectors are decaying far zone. Finally, full three-dimensional DNS optimally perturbed confirms presence structures determined analysis. time evolution perturbations presented. exhibits decay sometimes become similar those observed late stages Kelvin–Helmholtz billows. shown yield strong without transition turbulence.