open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi

we observe an unstability at the start of the model for an unknown reason ? do we have to start a mid tide to avoid this problem, or change some params ?

I send you a results which have been observed in some configurations of an hyper development in currents at the end of the session. What is the reason of this anomaly

I have another question concerning the coefficient of the .cas file for the TPXO base as you can read below

I am trying to use the harmonic base TPXO to make running Telemac 2D (a modelling programm for tidal current)

In the steering file for the program there are two main coefficients to set but I don't have any indication on these parameters ?

BINARY DATABASE 1 FOR TIDE = './tpxo/h_tpxo7.2'
BINARY DATABASE 2 FOR TIDE = './tpxo/u_tpxo7.2'

TIDAL DATA BASE = 2 /TPXO
MINOR CONSTITUENTS INFERENCE = YES

COEFFICIENT TO CALIBRATE SEA LEVEL = 1.14
COEFFICIENT TO CALIBRATE TIDAL RANGE = 0.0 ???

/COEFFICIENT TO CALIBRATE TIDAL VELOCITIES = 999999.0

The place I am working on is Wallis island in the South West Pacific about lat 13.2° S - long 176.2° W

The average sea level is about 1.1428 m in reference to 0 hydro of the marine charts

and NGWF is 1.21 m from the same reference (0 hydro of the marine charts)

there is no coefficient known for this station ?

are these coefficient depending on the place you are studying ? where to find an indication on these coefficient

thank you very much for a reply

Hello,

The first thing to do when you simulate tidal stream is to turn on the tidal flats option.

The instability at the beginning of your simulation may be due to your initial elevation condition of 0.98. You should better use tpxo altimetry in your case.

By default, tidal elevations from tpxo, prescribed at the boundary of your domain, are computed in relation to the mean sea level (chart datum + 1.1428m), so you have to check that the vertical reference of your model bathymetry is the mean sea level too.
Depending on which kind of conditions you are prescribing on your boundary (H, HUV), you can also play with Thompson option to avoid/reduce boundary instabilities.

The 3 coefficients you are speaking about are not requested in a first time, you can use default values. Once your model is stabilized, if you have in-situ measurements, you can play with them to adjust your model performance. Please see the section 4.2 (calibration of the information) to have more details about these 3 keywords.

Regards,
Laurent