||In the South China Sea, internal waves occur frequently, it is a site that important to|
study for internal waves, because the Donsha atoll just on path of internal waves
propagate. There is a step measured a phenomenon of cooling water at depth about 20
m on the Donsha atoll northeastern side by Wang et al.(2007). Further, Chen et al.
(2010) had simulated internal waves interacting with topography of Donsha atoll by
POM (Princeton Ocean Model), and found the internal waves bringing up cold deep
water to the shallows.
This study used the flume (12*0.5*0.7m) to set two-layers fluid system, and
generating internal solitary waves by gravity-collpse to simulating the interaction of
ISW with the topography model. This experiment focus on the variation of lower
layer fluid carried on the step by ISW. A digital camera and MicroADV are used for
save image and measure velocity for lower layer fluid on the step and then used
inertial dissipation to obtain the energy dissipation by velocity. Finally, we used the
k-ε turbulent model to obtain the eddy viscosity by energy dissipation.
On the other hand, this study also simulated by POM, and the model setting refer to
Chen et al.(2011). In order to enhance the mixing on the step, we modify turbulence
scale length to increase vertical eddy viscosity KH、Km in Mellor-Yamada turbulence
closure model, and KH、Km has increased indeed after modify, but it was unobvious
that enhance mixing. Besides, in the result of simulate, we found a downward vertical
velocity before internal waves into the step, this downward velocity has increased the
vorticity at depth about 6 m on the step, and it cause KH、Km to high between internal
waves and downward velocity.