in this paper, the flow of couple stress fluid is investigated in a helical screw rheometer (hsr). by unwrapping the channel, lands, and the outside rotating barrel, the geometry of hsr is approximated as a shallow infinite channel. both one- and two-dimensional analysis of the problem is presented using rectangular coordinates. in either case an exact solution of the flow problem is presented ...

In this paper, we derive a general relationship for the turbulent Prandtl number Pr t for homogeneous stably stratified turbulence from the turbulent kinetic energy and scalar variance equations. A formulation for the turbulent Prandtl number, Pr t , is developed in terms of a mixing length scale LM and an overturning length scale LE , the ratio of the mechanical (turbulent kinetic energy) deca...

The weakly nonlinear dynamics of quasi-geostrophic flows over a one-dimensional, periodic or random, small-scale topography is investigated using an asymptotic approach. Averaged (or homogenised) evolution equations which account for the flow-topography interaction are derived for both barotropic and continuously stratified geostrophic fluids. The scaling assumptions are detailed in each case; ...

A flow that arises in a turbulent wake behind a body that moves in a stratified fluid is rather peculiar. With a relatively weak stratification a turbulent wake first develops essentially in the same way as in a homogeneous fluid and extends symmetrically. However, buoyancy forces oppose vertical turbulent diffusion. Therefore a wake has flattened form at large distances from the body and, fina...

[1] Recent efforts to empirically measure and numerically simulate biogenic ocean mixing have consistently observed low mixing efficiency. This suggests that the buoyancy flux achieved by swimming animals in the ocean may be negligible in spite of the observed large kinetic energy dissipation rates. The present letter suggests that vertical migration across isopycnals may be necessary in order ...

Thermo-diffusion effect on free convection heat and mass transfer from a vertical surface embedded in a liquid saturated thermally stratified non Darcy porous medium has been analyzed using a local non-similar procedure. The wall temperature and concentration are constant and the medium is linearly stratified in the vertical direction with respect to the thermal conditions. The fluid flow, temp...

Turbulence experiments in a stratified fluid driven by set of internal gravity waves commonly lead to discretization the energy frequency and wavenumber due emergence eigenmodes domain. In this article, we present an experimental means inhibit process direct flow towards regime described weak internal-wave turbulence theory which aims at modeling oceanic dynamics small scales.

The flow generated by a sphere descending uniformly in a linearly stratified diffusive fluid is investigated numerically for different Reynolds (Re) and Froude (F ) numbers. The parameters used for the simulations were 10 ≤ Re ≤ 10 and 10 ≤ F ≤ 10, keeping the Schmidt number, Sc (= 700, typical of sea water) fixed. The results demonstrate drag dependence on viscosity and stratification, suggest...