open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello all,

I would like to run a telemac 2D model using the version of Teleamc: v7p3r1.

Could you pelase tell me if I am right:
OPTION FOR WIND=2
ASCII ATMOSPHERIC DATA FILE= 'holyhead_wind.txt'

Does a .txt file works or should I change the file format?

My telemac model run with a 2 s time step during two months but the wind data I have is every hour (3600 s). I understood that the wind file structure should be like this:
#time wind_x wind_y
0. -8.61 -1.51 (firt time step)
3600 -8.16 -1.49
7200 -9.154 -1.52
.
.
.
5270400 -5.26 -3.21 (last time step)

What will happen for the other time steps which does not correspond to the time increment of my wind data? Does the model assume that from 0 to 3600 the wind as the value of the first line, then from 3600 to 7200 the wind has the value of the second line etc...?

Thank you

Jonathan

Hi Jonathan,

Yes, you can provide a txt file for a wind varying only in time. I think you just have to add an extra line of comments at the beginning (with the units of time and wind, but the model does not read them).

Between the time steps you provide in this txt file, the model will linearly interpolate the wind components (see meteo.f around lines 240, variable COEF).

You can have a look at the "wind" example in /examples/telemac2d/wind ("fo1_wind" will show you the right format of the txt file).

Regards,
Laurent

Hi, Thank you for your answer.

I cant find the section example on Telemac web site... Could you pelase send me the link?

Regards

Jonathan

Examples should be in your telemac installation directory:
[$your_path_to_telemac_installation]/examples/telemac2d/wind

or from Telemac svn repository:
svn.opentelemac.org/svn/opentelemac/tags...ples/telemac2d/wind/

Regards,
Laurent

Perfect thank you!!!

Finger crossed it will work now...

Hi,

If I use OPTION FOR WIND = 2, do I still have to define the COEFFICIENT OF WIND INFLUENCE? Below, the keywords i used for the model:

WIND = YES
OPTION FOR WIND = 2
ASCII ATMOSPHERIC DATA FILE = 'wind_march_april_2018.txt'
THRESHOLD DEPTH FOR WIND = 1

I ran two different models one with wind and wihtout and the velocity look axactly the same...

Regards

Jonathan

I looked at the example and I dont understand why should I define the COEFFICIENT OF WIND INFLUENCE, WIND VELOCITY ALONG X and WIND VELOCITY ALONG Y as the wind varied in time.

Can someone eplain it to me please?

Regards

Hello Jonathan,

If you use OPTION FOR WIND = 2, the 2 keywords WIND VELOCITY ALONG X and WIND VELOCITY ALONG Y are not used (they are only used for OPTION FOR WIND = 1),
but COEFFICIENT OF WIND INFLUENCE is read and used. In TELEMAC-2D, the default value is 0. which means that if you set WIND = YES but let the default value for COEFFICIENT OF WIND INFLUENCE, you do not have differences with or without wind.

If you have a look at the examples in the trunk, a cleaning of the steering files was done for TELEMAC-2D examples 3 monts ago.

Anyway, as often recommended, you should use the last stable version v8p0r2 (e.g. in TELEMAC-3D, the default value for COEFFICIENT OF WIND INFLUENCE has been changed).

Hope this helps,

Chi-Tuan

Hello,

Thank you for your answer.

I am using the super computing wales where only the version V7P3r1 exist unfortunately as the model I am running is too big to be processed by my own computer in a reasonable time.

The wind for the time of my study varied from 0 to 16 m/s. In the Telemac users manual, it says that depending on the strenght of the wind the COEFFICIENT OF WIND INFLUENCE value varied. Its value is:

if Uvent< 5 m/s avent = 0,565 10-3
if 5 < Uvent< 19,22 m/s avent = (- 0,12 + 0,137*Uvent ) 10-3
if Uvent> 19,22 m/s avent = 2,513 10-3

I understand that for a constant wind in space and time, calculate the COEFFICIENT OF WIND INFLUENCE is easy. But for a wind varying in time (and not in space), how do I choose the COEFFICIENT OF WIND INFLUENCE?

Thank you very much for your time

Jonathan

Hello,

You can do what is implemented in the subroutine BORD3D of TELEMAC-3D, by adding the subroutine PROSOU of TELEMAC-2D in your FORTRAN FILE (if you use finite elements, PROSOU_FV if using finite volumes), something like:
Rather than in PROSOU:
DO N=1,NPOIN
IF (HN%R(N).GT.HWIND) THEN
WD = SQRT( WINDX%R(N)**2 + WINDY%R(N)**2 )
FU%R(N) = FU%R(N) + FAIR * WINDX%R(N) * WD / HN%R(N)
FV%R(N) = FV%R(N) + FAIR * WINDY%R(N) * WD / HN%R(N)
ENDIF
ENDDO
write:
! in the declarations of PROSOU subroutine
DOUBLE PRECISION ROAIR, RHO0, FAIR1
ROAIR = 1.3D0
RHO0 = 1000.D0 ! or 1025.D0 or another value depending on salinity and/or temperature
...
DO N=1,NPOIN
IF (HN%R(N).GT.HWIND) THEN
WD = SQRT( WINDX%R(N)**2 + WINDY%R(N)**2 )
! A MORE ACCURATE TREATMENT
IF(WD.LE.5.D0) THEN
FAIR1 = ROAIR/RHO0*0.565D-3
ELSEIF (WD.LE.19.22D0) THEN
FAIR1 = ROAIR/RHO0*(-0.12D0+0.137D0*WD)*1.D-3
ELSE
FAIR1 = ROAIR/RHO0*2.513D-3
ENDIF
FU%R(N) = FU%R(N) + FAIR1 * WINDX%R(N) * WD / HN%R(N)
FV%R(N) = FV%R(N) + FAIR1 * WINDY%R(N) * WD / HN%R(N)
ENDIF
ENDDO

By this way, the coefficient of wind influence may depend on velocity magnitude.
Be careful to use FAIR1 and not FAIR as you change the value.

Hope this helps,

Chi-Tuan