open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello：
Thanks for your attention.

I want to get a steady initial condition and then continue the calculation use the actual datas in the study area.
There are four boundary conditions, which two inflow at upstream(controlled by Q1,Q2), on outflow at midstream(controlled by Q3),and on outflow at downstream(controlled by Z). Please see the result picture.
The elevation at upstream is about 567, at downstream is about 465, so at first of the calculation, condition given as follow:

INITIAL CONDITIONS = 'CONSTANT ELEVATION'
INITIAL ELEVATION = 599.5


LIQUID BOUNDARIES FILE:

# Water Level at open boundaries
# MAODAOMEN estuary
#
T Q(1) Q(2) Q(3) SL(4)
s m^3/s m^3/s m^3/s m
0 20.00 10.00 0 599.5
86400 40.00 20.00 0 550.5
172800 60.00 30.00 0 500.5
259200 80.00 40.00 0 484.2
345600 80.00 40.00 0 480.7
432000 80.00 40.00 0 476.2
518400 75.00 80.00 0 470.7
604800 75.00 80.00 0 467.2
691200 75.00 80.00 0 467.2
777600 75.00 80.00 0 467.2
864000 75.00 80.00 0 467.2
950400 75.00 80.00 0 467.2


Also calculation continue about 10DAYS with the boundary Q1=75 Q2=80 Q3=0 Z=467.2, but the water surface decline very slowly, and the water depth just as follow showed:



the water depth variation given as follow(which just the last ten days of calculation)



In which way could I get the better steady initial condition which the water just flow in the riverway or if there another method usually used to get the initial condition?

Another question that give the rain and evaporation vary in time and space, the user manual suggest that they can be introduced through the meteo file, see water quality, wind and rain validation test cases (in folder examples/telemac2d), but I can't find the example file, is there anyone can show the name of the file?

Thanks
W_D

Hi,

yes, this is a typical problem by specifying an initial high water level since with the lowering water level the (unwanted) ponds in the floodplain will remain. Afterwards you could manually assign zero water depth to these nodes and use this file then as previous computation file.

Two other solutions:
either:
create manually a previous comnputation file by specifying an initial water depth in the rivers only. The initial water depths can be very approximate but with this file you should simulate a steady state low discharge result. The low discharge result will then be the previous computation file for further flood simulation.
or:
fill up the rivers only by specifying at the inlet boundaries the discharge and water depth and by specifying as initial condition a water depth at the inlet nodes only -> simulation of flow on dry bed. Again, after reaching a steady state the result will we be the previous computation file for further flood simulation.

Hope this helps,
Clemens

Hi,Clemens:

Thanks for your reply
I will try as you suggested, and also give the result maybe several days later.

Regards
W_D

Hello everyone,

I have read this topic and I want to know how you assign a very small water depth as initial conditions for the liquid boundaries and zero else where, I mean by the keyword INITIAL CONDITIONS? If yes how? because this keyword then needs a single value for the entire domain.

Thank you in advance.
Regards.

Hi
The easiest way is to give the initial water depth in a previous computational file.
The trick is to create manually this previous computational file with BK for example by opening the geometry file and adding a variable (Water depth).
Then you could give a spatial value...

It's also possible to use the PARTICULAR initial condition and then programming the initial value of water depth on the fortran file condin.f

Regards

Thank you, got it.

Regards.