tracer with a settling velocity

[osean]

Hi All
I am trying to implement a simple tracer with a constant settling velocity in ROMS.
So far I am able to set up a simple Lagrangian fluid particle by the FLOAT flag.
But I don't know if there is a way I can set a settling velocity for it.
Any guidance on how to do it / where to find the right cpp-flag and .in files to set it up would be helpful.
Thanks

[wilkin]

Do you want to do this with Lagrangian particles, or Eulerian tracers?

With tracers:

You can do this with the sediment model. Configure it with just a single sediment class and set the sinking velocity you want. Turn off all the options for resuspension etc. (unless you ultimately those). You can test with an initial condition of uniform concentration throughout the water column and you should see a sharp interface of "clear" water fall down at the settlng velocity until all the "sediment" is gone.

You could also adapt the REDTIDE model (in Nonlinear/Biology) where we also have the option for steady "upward swimming" of a tracer representing dinflagellates as a concentration.

With Lagrangian "floats" (sinkers):

See the FLOAT_OYSTER option to activate oyster model behavior in the floats code. You can manipulate the settings in there to give very simple sinking behavior and not much else.

[osean]

Do you want to do this with Lagrangian particles, or Eulerian tracers?

With tracers:

You can do this with the sediment model. Configure it with just a single sediment class and set the sinking velocity you want. Turn off all the options for resuspension etc. (unless you ultimately those). You can test with an initial condition of uniform concentration throughout the water column and you should see a sharp interface of "clear" water fall down at the settlng velocity until all the "sediment" is gone.

You could also adapt the REDTIDE model (in Nonlinear/Biology) where we also have the option for steady "upward swimming" of a tracer representing dinflagellates as a concentration.

With Lagrangian "floats" (sinkers):

See the FLOAT_OYSTER option to activate oyster model behavior in the floats code. You can manipulate the settings in there to give very simple sinking behavior and not much else.

The oyster float approach is interesting. Is there a test case that has oyster floats in it?

[wilkin]

There is no specific example in the myroms repository.

When you think of how many features ROMS has it's overwhelming to construct examples for everything. FLOAT_OYSTER is pretty straightforward - I'm sure you can figure it out.

But please feel free to contribute a test case - perhaps an option on an existing test like BIO_TOY or UPWELLING - and we can add that to the repository.