Evaluating the hydrodynamics of a round jet in a vegetated crossflow through large eddy simulation

摘要

Vegetation plays an important role on the turbulence structures of the effluent spreading in an open channel, which are insufficiently studied. This paper employs a large eddy simulation model to investigate the hydrodynamic processes of a round jet in a vegetated crossflow. The time-averaged simulated results are consistent with the experimental data. Analyses of mean flow characteristics including velocity distributions in different planes are showed that the array of rigid vegetation affects the averaged flow field and the jet structure, diminishing the velocity, with a significant increase of the jet penetration height. Moreover, this simulation successfully reproduces the coherent structures of classical and well-documented types based on the mean and instantaneous flow fields, including shear-layer vortices, wake vortices, counter-rotating vortex pair and windward vortex pair. The momentum transport mechanism is quantitatively elaborated by the quadrant analysis. Spectral analysis is adopted to obtain the dominant frequencies of vortex shedding and investigated the characteristic length of the large-scale vortex at different probes in the flow field.