open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I am currently working on a bacteriological model. The aim is to prevent pollutions.
I have done many simulations and I realized 2 things:

- First, when I modified the number of Horizontal Levels from 20 (1 level each 2 meters) to 24 (same thing + 1 level at -50, -100, -150 and -200 meters). There are some "irregularities" with the 24 levels simulation but I don't understand the reason (all other parameters are the same). (see Image_1)

- Second, when I increased the Time Step, with the same discharge (all other parameters are set), the velocity at the source tends to decrease (See Image_2).

Is it due to the representation of the hydromdynamics parameters ?

Thanks for your attention.
Julien.

Hi
About the vertical description. With 20 planes every 2 meters this cover only 38 m of water depth
You wrote you add 4 planes at -50, -100, -150 and -200 so you cover 200m of water depth.
There is a problem somewhere in your description.
The first plane is always the bottom and the last the free surface.
It could be great to know the exact position of planes in the simulation to try to understand the effect on temperature...

About the time step effect we need to know where is the source, how you described it? Could you confirm that the mesh stay the same for the various time step?

Regards

About the planes:
You're right, the first plane is the bottom and the last is the free surface. Between them there are 18 planes from -36m to -2m for the 20 planes simulation.
Currently I have a single source in the domain (which is at -36m), but I will add other sources that's why I need dto add more planes becasue there are sources at -100m.
For the 25* (I forgot to count the bottom) planes i have:
Plane(1)=bottom
ZPLANE%R(2)=-150.D0
ZPLANE%R(3)=-125.D0
ZPLANE%R(4)=-100.D0
ZPLANE%R(5)=-75.D0
ZPLANE%R(6)=-50.D0
And then from -36m to surface.
I mentioned -200 because when I visualize results on BlueKenue it's the deepest plane.
So the 2 simulations cover the same domain.
temperature and salinity are defined as Tracers. And I initialized for each depth the temperature and salinity (until -36m and after the values are the same as -36m).

About the Time step:
So the source's location is -36m.
And I can confirm that the mesh is the same for each of these Time Step (50m resolution in the domain except in a 50m circle around the source where it is a 3m resolution). And for the vertical planes:
ZPLANE%R(2)=-35.D0
ZPLANE%R(3)=-34.D0
ZPLANE%R(4)=-33.D0
ZPLANE%R(5)=-32.D0
ZPLANE%R(6)=-31.D0
ZPLANE%R(7)=-30.D0
ZPLANE%R(8)=-29.D0
ZPLANE%R(9)=-28.D0
ZPLANE%R(10)=-27.D0
ZPLANE%R(11)=-26.D0
ZPLANE%R(12)=-25.D0
ZPLANE%R(13)=-24.D0
ZPLANE%R(14)=-23.D0
ZPLANE%R(15)=-22.D0
ZPLANE%R(16)=-21.D0
ZPLANE%R(17)=-20.D0
ZPLANE%R(18)=-19.D0
ZPLANE%R(19)=-18.D0
ZPLANE%R(20)=-17.D0
ZPLANE%R(21)=-16.D0
ZPLANE%R(20)=-15.D0
ZPLANE%R(21)=-14.D0
ZPLANE%R(22)=-12.D0
ZPLANE%R(23)=-10.D0
ZPLANE%R(24)=-8.D0
ZPLANE%R(25)=-6.D0
ZPLANE%R(26)=-5.D0
ZPLANE%R(27)=-4.D0
ZPLANE%R(28)=-3.D0
ZPLANE%R(29)=-2.D0
ZPLANE%R(30)=-1.D0
The exact position of the source is defined in the .cas as:
ABSCISSAE OF SOURCES : 1045230.9375
ORDINATES OF SOURCES : 6297438.0
ELEVATIONS OF SOURCES : -36
+ I have a source file where the discharge and the tracers are defined
(I added "SourcePaioleMoy-13h" if you wantto see it)

I hope it is clear, if not I can add the parameter and fortran files.

Regards

Hi
you place a source at -36 which is the 2nd plane.
In the source management, there is a computation of the volume surrounding the source. In your case, the distance under the source, define by the mesh is really great in the first case.

I would advise you to try to control the cell size around your sources in order to limit vertical meshing effects...

Regards

I will try to add more planes under the source.

Thank you for your help.

Regards

Hello,

I added 2 planes under the source (-38m and -40m) and did new simulations.
The 27 planes simulation (which is the ancient 25 planes simulation) has the same type of "irregularities" than the 25 planes one.
I add a screenshot of graphs I obtained with 20, 25, 22, 27 planes simulations and a 30 planes simulation (the 30 planes simulation comes from the previous model done by my colleague and had good results)(the postition of the planes are detailled in my last message in the Time Step part).
Edit: i can't add the file, sorry.

Shall I have to add more planes under my source ?

Do you think that the remark about the velocity (which decrease when the time step increase) is linked to vertical meshing effects ?

Regards