wind gradient for sailing boat
 

Hi all,
i'am working on sailing boat finemarine simulations and I would like to modeling the wind as close as possible of the reality, so with a velocity gradient, U function of altitude z .
I have read the Manuel, p207, but I would appreciate some help if anybody did this before, in particular the little fortran program.
Thank very much by advance LL

Hello Laurent,

I haven't done yet this kind of computations in Fine Marine, but you will need a background mesh with a vertical gradient in the cell size in order to model a velocity gradient. In order to make such a mesh in Hexpress, I got this guidelines from the support:

In a first project:
1) define a 1st domain (without the geometry you want to mesh) which has the exact same dimensions as the domain you would like to have at the end.
2) At initial mesh step, chose X and Y resolution as you need it, and chose 3 cells in the Z direction.
3) In the adaptation step, do not define any refinement but set the top and bottom boundaries as "Used for trimming". (You will have just one layer of cells in your domain after that step)
4) In the expert parameters of the snapping step, deactivate the "buffer insertion" option
5) In the viscous layer step, define on the bottom boundary the viscous layer you need as background mesh

In a second project:
6) Create a 2nd domain of the same dimension as the 1st domain, but which includes you geometry
7) At the Initial Mesh step, chose the option "Import mesh" and import the mesh from the first project.
8) Define the remaining mesh parameters as usual.

It is not exactly what you asked for but I hope this helps :)