Quantifying and predicting intermittency in stably stratified plane Poiseuille flow*

Under sufficiently strong stratification, fully developed wall-bounded turbulent flows could transition to intermittent flows in which laminar and turbulent patches coexist. Using direct numerical simulations, we explore the boundary at which such transitions occur in the parameter space for stably stratified plane Poiseuille flow. A range of friction Reynolds and Richardson numbers, parameters that are observed to control the dynamics, are covered by the numerical simulations, which enable us to examine the applicability of various dimensionless parameters for predicting the occurrence of intermittency. We quantify the volume fraction of turbulent patches in each simulation and use these statistics to predict the occurrence of intermittency. Preliminary results suggest that the intermittency criterion documented for stratified plane Couette flow (Deusebio et al., J. Fluid Mech., volume 781, 2015) may not apply for the plane Poiseuille flow case. Alternative criteria for predicting intermittency are examined.