Three-dimensional features of the lateral thermal plume discharge in the deep cross-flow using dynamic adaptive mesh refinement

The lateral thermal plume discharge in the deep cross-flow has been investigated by numerical simulation using the open-source Open FOAM code. Adaptive mesh refinement method has been applied to reduce the computational cost. The numerical simulation results show a good agreement with the previous experimental data. Three-dimensional structures illustrated by instantaneous velocity fields indicate shear layer roll-up vortices around the discharged plume. As the densimetric Froude number \((\hbox {Fr}_{0})\) is increased, the buoyant plume penetrates more in the depth of the channel and fewer spreads in the free surface. As the \(\hbox {Fr}_{{0}}\) decreases, the coherent structures become increasingly weak, with the faster breakdown of the shear layer roll-up. The instantaneous temperature contours near the free surface exhibit a vortex shedding phenomenon. Three-dimensional streamlines based on the instantaneous velocity vectors illustrate a swirl flow pattern downstream of the main channel. Increasing the \(\hbox {Fr}_{{0}}\) results in weakening the swirl flow around the discharged jet core. The mixing ability of discharged plume is investigated by temporal mixing deficiency (TMD) and spatial mixing deficiency (SMD) indices. The statistical analysis of the TMD and SMD reveals the direct relationship between the mixing efficiency and reduced gravity.