Turbulent diffusivity closures and large eddy simulation models

A turbulent diffusivity closure representing the effects of viscous dissipation and diffusion can be passed via the closure keyword.

See turbulence closures and large eddy simulation for more details on turbulent diffusivity closures.

Constant isotropic diffusivity

To use constant isotropic values for the viscosity ν and diffusivity κ you can use IsotropicDiffusivity

julia> using Oceananigans.TurbulenceClosures

julia> closure = IsotropicDiffusivity(ν=1e-2, κ=1e-2)
IsotropicDiffusivity: ν=0.01, κ=0.01

Constant anisotropic diffusivity

To specify constant values for the horizontal and vertical viscosities, $\nu_h$ and $\nu_v$, and horizontal and vertical diffusivities, $\kappa_h$ and $\kappa_v$, you can use AnisotropicDiffusivity

julia> using Oceananigans.TurbulenceClosures

julia> closure = AnisotropicDiffusivity(νh=1e-3, νz=5e-2, κh=2e-3, κz=1e-1)
AnisotropicDiffusivity: (νx=0.001, νy=0.001, νz=0.05), (κx=0.002, κy=0.002, κz=0.1)

Smagorinsky-Lilly

To use the Smagorinsky-Lilly LES closure, no parameters are required

julia> using Oceananigans.TurbulenceClosures

julia> closure = SmagorinskyLilly()
SmagorinskyLilly: C=0.16, Cb=1.0, Pr=1.0, ν=0.0, κ=0.0

although they may be specified. By default, the background viscosity and diffusivity are assumed to be the molecular values for seawater. For more details see SmagorinskyLilly.

Anisotropic minimum dissipation

To use the constant anisotropic minimum dissipation (AMD) LES closure,

julia> using Oceananigans.TurbulenceClosures

julia> closure = AnisotropicMinimumDissipation()
AnisotropicMinimumDissipation{Float64} turbulence closure with:
           Poincaré constant for momentum eddy viscosity Cν: 0.08333333333333333
    Poincaré constant for tracer(s) eddy diffusivit(ies) Cκ: 0.08333333333333333
                        Buoyancy modification multiplier Cb: nothing
                Background diffusivit(ies) for tracer(s), κ: 0.0
             Background kinematic viscosity for momentum, ν: 0.0

no parameters are required although they may be specified. By default, the background viscosity and diffusivity are assumed to be the molecular values for seawater. For more details see AnisotropicMinimumDissipation.