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Dear All,

This is regarding specifying the vertical velocity profile. I am using Telemac-3D in simulating the flow in river confluence. I have 3 liquid boundaries which are set as 2 inflow-discharge and 1 downstream stage elevation.

My question if I don't specify any vertical velocity profile how is the discharge distributed between the vertical planes (layers).

For some reason if I start with the simulation with 0 velocities in the domain, I see all the velocity vectors going in positive z direction (after 1st time-step only and continues to do so) near both the inflow regions.

For this particular trial I am keeping the value of both:
HORIZONTAL TURBULENCE MODEL = 1
VERTICAL TURBULENCE MODEL = 1
and specify there values as 1.E-05

All suggestions are greatly appreciated.

Thanks,
Sumit

Hello,

By default the vertical velocities are free even on entries with prescribed discharge (it is better when there is a slope at the entrance, then the vertical velocities are not 0). You can have vertical velocities set to zero by changing bord3d.f, at the beginning you have to uncomment the section :

!
! IMPORTANT OPTION:
! VERTICAL VELOCITIES ARE SET AS HORIZONTAL VELOCITIES
! THIS IS AN OPTION, OTHERWISE LIWBOL=KSORT (SEE LIMI3D)
!
! DO IPTFR = 1,NPTFR2
! IPOIN2 = NBOR2%I(IPTFR)
! DO IPLAN = 1,NPLAN
! IBORD = (IPLAN-1)*NPTFR2 + IPTFR
! LIWBOL%I(IBORD)= LIUBOL%I(IBORD)
! IF(LIWBOL%I(IBORD).EQ.KENT) WBORL%R(IBORD) = 0.D0
! ENDDO
! ENDDO
!

with best regards,

Jean-Michel Hervouet

Thanks a lot Jean-Michel

Sumit

I am having the similar issue when modeling the flow in river confluence. I have tried different boundary conditions (UV, UV and H, Q, Q and H). In all cases, I have high vertical velocities (10-30 m/s) by the boundary.

I have attached a sample model output. The contour shows the water surface. The contour spacing is 1 m. Close to the source, the water surface is 52 m. Is there anything that I can do to reduce the surface gradient? I suspect that this is why I am getting high vertical velocities.

The average mesh size by the liquid boundary is 0.30 m. The exit velocity is 2 m/s and my model time step is 0.125 sec.

Thanks.

Edwin

Please ignore the previously attached image and refer to this one instead.
The contour interval is 0.2 m.

Hi Edwin,

Have you tried following what Jean-Michael suggested, un-commenting the section in bord3d.f. My problem was solved by doing that.

Hope this helps,

Cheers
Sumit

Hi Sumit,

I have tried it but with the Q&H liquid boundary condition. I just looked at the codes closely and I believe that section is only applicable for Q only boundary condition. I will give that a try.

Edwin