Double precision Mohid executable and tools

MOHID Water forum. Questions and discussion around MOHID Water
gonzalo.dizlois.palomares@xunta.es
MOHID Beginner
Posts: 5
Joined: Thu Jan 01, 1970 00:00

Double precision Mohid executable and tools

Postby gonzalo.dizlois.palomares@xunta.es » Fri Jan 22, 2010 10:40

Hi,

I'm new at this, but I managed to build a simple simulation (this should be just a trial) to become more confident before daring to build more complex ones. I'm an autodidact to mohid since I've been learning through your wiki and forum websites and now I have a more determined idea of what I need to achieve good simulations. You're doing a great scientific divulgation job!
Now I have a model with very little grid spacing (2x2 m), I intend to use mohid around ports and near the coast, so this dx and dy are not THAT absurd, although this is just a trial, as I said.
Doing some research around the forum I managed to isolate the problem: I need the double precision *.exe to run the model, please, could you send It to me: gonza.dlp@gmail.com. Thanx!
I also tried to get the TydeAnalyzer application for matlab, is it avalaible? can I have it?
Now some miscelaneous questions?
1.-You cannot nest curvilinear grids. Right? Is there much diference in the accuracy of a simple and a curvilinear grid?
2.- Is mohid suitable for closed basins?, nearcoast?, and shallow waters?
3.-How can you introduce wind forcing?, just including the keywords in hydrodynamic.dat and atmosphere.dat would do? Is the ekman wind profile supported?
4.-How can we solve the problems with open boundary conditions(obc)? (what exactly is an open boundary condition?, is a dirichlet bd? (ex fixing water level with tide along a line)). What kind of problems can arise because of obc?

I know some of these are general questions, but references to bibliography, to mohid wiki, or to other web would be welcomed.
Thank you again, and congratulations to your contribution to science worldwide!!
Gonzalo Diz Lois Palomares. Portos de Galicia. Spain.

paulo.chambel@hidromod.com
MOHID Advanced user
Posts: 117
Joined: Thu Jan 01, 1970 00:00
Location: Lisbon
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Postby paulo.chambel@hidromod.com » Wed Jan 27, 2010 01:26

Hi,

in coastal applications of mohid there is no reason why a double precision and single precison versions can give significant different solutions.

1.-You cannot nest curvilinear grids. Right? Is there much diference in the accuracy of a simple and a curvilinear grid?

You can nest curvilinear grides with the same curvature. The curvilinear grid is a little bit dangerous from the accuracy point of view. The curvilinear grid generators minimize the deviations to the grid orthogonality. This means that if you define a complex polygon for the boundary of your domain the grid will be approximatly orthogonal this will induce small errors that can be not so small in areas of strong velocities. I'm only using curvilnear grids to simulate rivers not anything else,

2.- Is mohid suitable for closed basins?, nearcoast?, and shallow waters?
Yes, yes, yes,

3.-How can you introduce wind forcing?, just including the keywords in hydrodynamic.dat and atmosphere.dat would do?

No you need to define the wind stress X and Y in the intrfaceWaterAir. In fact you impose a wind stress and not a wind velocity. You can use the win velocity to compute the wind stress.

Is the ekman wind profile supported?

Yes because the model can be 3D and it takes in consideration by default the coriolis force.

4.-How can we solve the problems with open boundary conditions(obc)? (what exactly is an open boundary condition?, is a dirichlet bd? (ex fixing water level with tide along a line)). What kind of problems can arise because of obc?

Boundary conditions is a very big area of research

I recommend reading this PhD thesis http://www.mohid.com/PublicData/Product ... _PauloLeitão.zip

I will ask a collegue to send you the tide analyser tool develop in matlab.

Best regards,
Paulo
The peace be with you

gonzalo.dizlois.palomares@xunta.es
MOHID Beginner
Posts: 5
Joined: Thu Jan 01, 1970 00:00

Postby gonzalo.dizlois.palomares@xunta.es » Fri Jan 29, 2010 08:59

Thank you for your quick response, I appreciate ...
I'm improving my models now.

Now I wanted to ask another question, but I'll make another post because It deals with nested grids... see you!


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