open TELEMAC-MASCARET The mathematically superior suite of solvers

I am aware that there is the LIMWAC subroutine that allows for the spatial variation of spectral components. Is there a method in tomawac for imposing a boundary condition wave height (Hm0) that varies temporally ?

Hello,

if you want to impose boundary conditions varying in time, you have to code this in the fortran file of the TOMAWAC simulation.
The simplest case is to impose non-stationary (varying with the time) and uniform (same value at each point of the boundaries) boundary conditions. In this case what you could do is to read the boundary conditions from a formatted file (e.g. a .txt file) that you create and in which, at each line, you specify the time step and the corresponding reduced input spectral parameters (significant wave height, peak period, mean propagation direction, ...).
The steps to follow are:
1- you create your formatted file with the time depending boundary conditions
2- In the steering file you specify the name of this formatted file via the keyword FORMATTED FILE 1 (see chapter 7.2.13 of the TOMAWAC guide)
3- You modify LIMWAC in order to manage the read operations of this file within the FORTRAN program: at each time step LIMWAC read the spectral parameters from the file and use them as argument variables in the call to SPEINI.
This is the approach I use generally. Of course it is not the only possible approach.

In the case you have boundary conditions that are non-stationary and non-uniform, the approach to follow could the same as above, but in this case you have to do a loop over all the points of the boundary to assign at each time step a different Hm0 at each node of the boundaries.

Hope it helps.
Kind regards,

Giovanni

Yes sir this has been most helpful thank you.

Hello,

Can you tell me what's the difference between SPEINI and SPEJON?
Is it the same thing if I call SPEJON at "t=0" and "t>0" ?

Sincerely
Kroptia

Hello,

the subroutine SPEINI calculates the parameters needed by SPEJON or SPETMA to calculate the wave spectrum, depending on the value assigned to the keyword TYPE OF INITIAL DIRECTIONAL SPECTRUM and TYPE OF BOUNDARY DIRECTIONAL SPECTRUM (please see chapters 8.4 and 8.5 of the manual). SPEINI passes then those parameters to the subroutines SPEJON (Jonswap spectrum case) or SPETMA (depth-corrected Jonswap spectrum case), which calculate the wave spectrum.

It is not really clear for me what you mean when you ask which is the difference when calling SPEJON at t=0 and t>0.
You can have a look at the subroutine LIMWAC:

• If you have stationary boundary conditions LIMWAC calls SPEINI (and then SPEJON or SPETMA) only at the first time step (t=0): the boundary spectra needed to be calculated only once because they do not change during the simulation.
• If you have non-stationary boundary conditions (or if the boundary spectrum is modified by the user, i.e. the keyword SPEULI is set to true), then the boundary conditions must be calculated at each time step: in this case LIMWAC calls at each time step SPEINI (and then SPEJON or SPETMA).

Kind regards,

Giovanni

Hai


I have measured wave data at 12m depth for the study area a new region along indian coast of Arabain sea.I want to set the model to this area.so I want validate the nearshore waves with TOMAWAC for future studies.Howe can I validate and perform sensitivity analysis.Kindly help me with suitable information.


regards,

Glejin

Hello,

to validate/calibrate your model, you have to reproduce in TOMAWAC the wave climate occurring during the wave data measurement period. The steps to do are the following:

• set a model domain that includes the area in which the wave data are measured
• the boundaries of your model shouldn't be too close to the area of the wave data measurements
• if your domain is limited to a specific area of the Indian Ocean, you have to impose sea-state boundary conditions taken from a meteorological model or from a sea-state reanalysis. Those boundary conditions vary in space and time (to implement this in TOMAWAC, please, refer to my previous post in this forum topic). Only in the case of a very large (global) model you can avoid to impose sea-state conditions at the boundaries: in this case you can make the assumption that the model domain is so large that all the waves that reach the coasts are generated by the wind within the model
• if your model is larger than few hundreds km square, you should take into account also the wind forcing: to do that, you have to impose over the TOMAWAC domain wind fields obtained from a meteorological model or from a meteorological reanalysis and interpolated over the TOMAWAC grid (please refer to the TOMAWAC guide to have some info concerning the wind data format to use). Those wind data must cover the same period covered by the spectra imposed at the boundaries.
• once you have set the sea-state boundary conditions and the forcing wind fields, you run your TOMAWAC model and you can compare the model results at the wave data measurements location with the measured wave data.
• you can carry out sensitivity analysis by varying the simulation time step (to find the best compromise between computational time and accuracy of the results) and by using different source term formulations

Those are the basic steps that I generally carry out for this kind of studies. You can find many exemples in the literature that can help you in defining your model and carry out the simulations.
Hope it helps.
Kind regards,

Giovanni