Bottom Enhanced Mixing

[msdevana]

Hi Oceananigans Community!

I am just starting out playing with Oceananigans and trying to do some experiments examining bottom enhanced mixing .
Any tips on how to specify a bottom enhanced diffusivity profile rather than a constant value?

Thanks!
Manish

[glwagner]

From the docstring for ScalarDiffusivity:

`ν` and the fields of `κ` may be constants (converted to `FT`), arrays, fields or
  - functions of `(x, y, z, t)` if `discrete_form = false`
  - functions of `(i, j, k, grid, LX, LY, LZ)` with `LX`, `LY` and `LZ` are either `Face()` or `Center()` if
    `discrete_form = true`.

So, you can use a function with a bottom-enhanced shape like

@inline κ(x, y, z, t) = κ0 + κ1 * exp(-(z + H)^2 / (2*d^2))

where z=-H is the bottom and d is the decay scale of the region of enhanced mixing. Or, you can provide an array with discrete values for the diffusivity.

[msdevana]

Thank you! Super helpful and straightforward