Evolution of the propeller near-wake and potential energy in a thermally-stratified environment

The unsteady near-wake of a self-propelled body in a linearly stratified environment is studied through the novel use of an actuator-line model. A comparison to experiment at Re
_L
= 1.6×10
⁶
shows agreement in wake profiles and the emergence of individual blade-wake structures. Increasing the Reynolds number to Re
_L
= 3.1×10
⁸
reveals a delayed vortex breakdown and relative reduction in velocity profile magnitude, in addition to a thinner boundary layer and reduced skin-friction coefficient as predicted by theory. Downstream turbulent-kinetic, mean-kinetic, and potential energies reveal the persistence of swirl and growth of potential energy, which is embodied as a mixed patch. While velocity and turbulent-kinetic energy are axisymmetric in the mixed patch, the temperature field grows into a unique profile that is asymmetric in the azimuthal direction.