Turbulent/Non-turbulent Interface properties of a temporally developing turbulent jet

In many free shear flows such as turbulent boundary layers, wakes, or jets, a turbulent/non-turbulent interface (TNTI) separates the turbulent and the irrotational flow regions. This sharp and highly non-homogeneous region of the flow raises new modeling problems in the frame of large-eddy simulation for instance. Important exchanges of mass, momentum, and scalar quantities take place across this interface and lead to the propagation of the turbulent region known as turbulent entrainment. In this study, we investigate the geometrical properties and interscale energy transfer mechanisms at the TNTI in a temporally developing turbulent jet using data from highly resolved direct numerical simulations. We calculate the mean velocities and turbulence statistics in the vicinity of the TNTI thin layer conditional on characteristics such as TNTI position, orientation, curvature and local propagation speed relative to the fluid. A very special attention has been paid to the influence of the overall resolution and quality of the simulation on the TNTI properties.