## Lagrangian tracer at a non-zero depth with wind transfer

MOHID Water forum. Questions and discussion around MOHID Water
florian.huhn@gmx.de
MOHID Beginner
Posts: 1
Joined: Thu Jan 01, 1970 00:00

### Lagrangian tracer at a non-zero depth with wind transfer

Hello,
I am using the Lagrangian Module to model surface drifters and would be glad about some help for the following problem:

Imagine a drifter with a floating part subjected to wind and a submerged part at 5m depth (drogue).

I would like to advect the tracer with a wind influence, say WINDCOEF = 0.01 and a water depth of DEPTH_METERS = 5. This should give an instantaneous tracer velocity as a linear combination of the wind speed and the water velocity at 5m depth.

As I understand it, this is not possible, because you can either have a floating particle (FLOAT = 1) at zero depth with wind influence (WINDCOEF = 0.01), or a submerged particle at 5m (DEPTH_METERS = 5) without any wind influence.

Am I right? How can I fix it?
I would like to vary both parameters (WINDCOEF, DEPTH_METERS) to fit modeled trajectories to real drifter trajectories.

Thanks for your help
Best wishes
Florian

rodrigo.maretec@ist.utl.pt
MOHID Beginner
Posts: 8
Joined: Thu Jan 01, 1970 00:00

### Lagrangian tracer at a non-zero depth with wind transfer

Hi Florian,
In fact, changes are happening in MOHID Lagrangian Module right now, to take in account the possibility of simulating floating drifters with a drogue at x meter depth, and still have the explicit influence of the wind in the floating buoy.

After the changes, it is possible to have FLOAT = 1 + DEPTH_METERS = 5 + WINDCOEF = 0.01.

These changes were made in the scope of DRIFTER project that we both know very well...right ?

The source code will be available in Codeplex between tomorrow and Monday.
Cheers
Rodrigo