[Elaheh 1995]

hi there everyone
I am modeling an open channel spillway with flow3d and it is almost functioning but the problem I have is that the velocity profile is not as desired (it is not zero near the walls and bottom of the channel and it is not maximum near the surface of the water)
the boundary condition that I have used is as follows:

xmin=pressure with fixed fluid elevation
xmax=pressure outflow
ymin/ymax and zmin=wall
zmax=pressure with fluid fraction=0

does anyone know what should I do to have ideal velocity profiles?
thanks a lot
20 jan.jpg

[MSM1985]

As seen from figure, flow is controlled at inlet by orifice openings, so its just like bottom outlet spillway (not traditional open channel flow). Due to two openings, flow is distributed in two paths. This effect will diminish some distance downstream of the openings. As 'red contours' are getting closer, either refined mesh size or increasing downstream channel length will show maximum velocity contours in middle of channel. Maximum water surface velocity occurs 0.05 to 0.25 of the depth for channels. Also its better to extract the results when flow is nearly steady.

Boundary conditions are OK.

[Elaheh 1995]

Originally Posted by MSM1985

As seen from figure, flow is controlled at inlet by orifice openings, so its just like bottom outlet spillway (not traditional open channel flow). Due to two openings, flow is distributed in two paths. This effect will diminish some distance downstream of the openings. As 'red contours' are getting closer, either refined mesh size or increasing downstream channel length will show maximum velocity contours in middle of channel. Maximum water surface velocity occurs 0.05 to 0.25 of the depth for channels. Also its better to extract the results when flow is nearly steady.

Boundary conditions are OK.

thanks a lot for your response. it was really helpful