John Singler

Transition to turbulence, small disturbances and sensitivity analysis

Predicting transition to turbulence is one of the longstanding problems in
fluid mechanics.  Recently, new transition scenarios have been proposed
that are based on the sensitivity of the linearized equations of motion
with respect to small disturbances.  These new “mostly linear”
theories have increased our understanding of the transition process, but
the role of nonlinearity has not been explored.  In this talk, we explore
the interaction of small disturbances with nonlinear model transition
problems.  We demonstrate that small forcing or small wall roughness can
trigger transition.  Also, we use sensitivity analysis to predict the
behavior of the disturbed systems.