ﻻ يوجد ملخص باللغة العربية
In this study, we focus on Langmuir turbulence in the deep ocean with the presence of a large macroalgal farm using a Large Eddy Simulation method. The wave-current interactions are modelled by solving the wave-averaged equations. The hydrodynamic process over the farm is found to drive a persistent flow pattern similar to Langmuir circulations but is locked in space across the farm. These secondary circulations are generated because the cross-stream shear produced by the rows of canopy elements leads to a steady vertical vorticity field, which is then rotated to the downstream direction under the effect of vortex force. Since the driving mechanism is similar to the CraikLeibovich type 2 instability theory, these secondary circulations are also termed as attached Langmuir circulations. We then apply a triple decomposition on the flow field to unveil the underlying kinematics and energy transfer between the mean flow, the secondary flow resulting from the farm drag, and the transient eddies. Flow visualizations and statistics suggest that the attached Langmuir circulations result from the adjustment of the upper ocean mixed layer to the macroalgal farm, and they will weaken (if not disappear) when the flow reaches an equilibrium state within the farm. The tripledecomposed energy budgets reveal that the energy of the secondary flow is transferred from the mean flow under the action of canopy drag, while the transient eddies feed on wave energy transferred by the Stokes drift and energy conversion from the secondary flow.
The large-scale structures in the ocean and the atmosphere are in geostrophic balance, and a conduit must be found to channel the energy to the small scales where it can be dissipated. In turbulence this takes the form of an energy cascade, whereas o
Recent numerical simulations showed that the mean flow is generated in inhomogeneous turbulence of an incompressible fluid accompanied with helicity and system rotation. In order to investigate the mechanism of this phenomenon, we carry out a numeric
We investigate a mechanism to manipulate wall-bounded flows whereby wave-like undulations of the wall topography drives the creation of bespoke longitudinal vortices. A resonant interaction between the ambient vorticity of the undisturbed shear flow
The flow speed-up generated by windbreaks can be used to increase the power production of wind turbines. However, due to the increased drag imposed by the windbreaks, their use in large wind turbine arrays has been questioned. We use large eddy simul
We investigate the dynamics of cohesive particles in homogeneous isotropic turbulence, based on one-way coupled simulations that include Stokes drag, lubrication, cohesive and direct contact forces. We observe a transient flocculation phase character