vertical mixing in specific range

[CaroMedel]

I'm using vertical mixing, but I only want the particles to oscillate within a specific range. How can I define that range?

Best, Caro

[AndresSepulveda]

Hi Caro,

Do you mean vertical migration? In response to daylight, for example?

[CaroMedel]

Hi Andrés,

No, I want the particles move with the vertical mixing, only inside the mixed layer, which is defined as 20 m. When I activate the vertical mixing, the particles move even below 80 m.

[AndresSepulveda]

You could add to the IBM something like

depth = min(maxDepth, current_depth)

to force the particle to stay in the maxDepth that you specify. But unless the particle has some sort of vertical migration capability (buoyancy adjustment?) it might not be very physical.

[knutfrode]

Hi,

Please see this example:

https://opendrift.github.io/gallery/example_mixed_layer_depth.html#sphx-glr-gallery-example-mixed-layer-depth-py

Here vertical diffusivity is parameterized from wind. If you instead obtain it from ocean model, it will generally not be nonzero below a specific depth, and thus mixing can continue to seafloor, although normally less mixing below ~20m.

On Wed, May 10, 2023, 19:58 Carolina Medel @.***> wrote:

Hi Andrés,

No, I want the particles move with the vertical mixing, only inside the mixed layer, which is defined as 20 m. When I activate the vertical mixing, the particles move even below 80 m.

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[CaroMedel]

thanks to both of you

[CaroMedel]

Hi Trond,

I checked the example you mentioned, but it still doesn't work. The particles go below 20 meters.

I need the particles to always stay above 20 meters. I'm using the following:

terminal_velocity = 0 'ocean_vertical_diffusivity': {'fallback': 0.001, 'profiles': True}, 'ocean_mixed_layer_thickness': {'fallback': 20}

o.set_config('drift:vertical_mixing', True) o.set_config('vertical_mixing:diffusivitymodel', 'windspeed_Large1994') o.set_config('vertical_mixing:background_diffusivity', 0)

I've used the other diffusivity models too, is there any other way to do what i want?

Thanks

[knutfrode]

Could you share a minimalistic example that reproduces this problem?