Specifying the Velocities at the Boundaries

Often it is necessary to specify the velocity direction for the boundary condition using PRESCRIBED VELOCITIES=2. Below is an example showing the velocity component for flow in a 45 degree direction.


4 5 5 0.0 0.625 0.625 0.0 4 0.0 0.0 0.0 429 1
4 5 5 0.0 0.625 0.625 0.0 4 0.0 0.0 0.0 643 2
4 5 5 0.0 0.625 0.625 0.0 4 0.0 0.0 0.0 857 3
4 5 5 0.0 0.625 0.625 0.0 4 0.0 0.0 0.0 1071 4
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1072 5
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1073 6
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1074 7
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1075 8
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1076 9
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1077 10
2 2 2 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 1078 11

5 4 4 0.0 0.625 0.625 0.0 4 0.0 0.0 0.0 1284 217
5 4 4 0.0 0.625 0.625 0.0 4 0.0 0.0 0.0 1070 218


LIHBOR, LIUBOR, LIVBOR, HBOR, UBOR, VBOR, AUBOR, LITBOR, TBOR
ATBOR, BTBOR, N, K



LIHBOR, LIUBOR, LIVBOR, and LITBOR are the boundary type codes for each of
the variables


For most of our work the first three values will be

2 2 2  Solid boundary.
4 5 5  Free H, prescribed Q
5 4 4  Prescribed H, free velocities.

HBOR (real) represents the prescribed depth if LIHBOR = 5.
UBOR (real) represents the prescribed velocity U if LIUBOR = 6.
VBOR (real) represents the prescribed velocity V if LIVBOR = 6.

However if PRESCRIBED VELOCITIES=2,  In the case of a prescribed flowrate, then UBOR and VBOR are multiplied by a constant in order to reach the prescribed flowrate.




Section 4.2.2/4.2.3 of the Telemac2D manual provides additional information.