They study the motion of inertial solid particles across stratified turbulent/non-turbulent interfaces (STNTI). Previous studies in quiescent stratified layers demonstrated that inertial particles slow down due to an additional force term related to the stratification.

They report for the first time a similar effect on inertial particles moving across a two-layer STNTI of finite thickness. The problem is addressed both experimentally and numerically: They utilize the three-dimensional particle tracking velocimetry (3D-PTV) in a index-matched STNTI experiment under an oscillating grid, and two direct numerical simulation (DNS) cases of STNTI. The numerical spheres are tracked using a modified Basset–Boussinesq–Oseen equation that includes the stratification force, modelled as the buoyancy of a caudal wake with varying density.

Numerical results for the STNTI cases help to distinguish the essential features observed in the experiments that are caused by stratification from those that relate to turbulence–particle interactions.

Link to the paper:

https://www.sciencedirect.com/science/article/pii/S0301932222001410?utm_campaign=STMJ_AUTH_SERV_PUBLISHED&utm_medium=email&utm_acid=260305298&SIS_ID=&dgcid=STMJ_AUTH_SERV_PUBLISHED&CMX_ID=&utm_in=DM267652&utm_source=AC_