Hello, everyone,
Currently, at my work, we develop lots of projects that cover concrete trapezoidal channels which intersect roads, under which we design box culverts.
We generally develop steady flow, one-dimensional modeling and design the transition between the trapezoidal channels to the box culverts using concrete sidewalls, typically at 45 degrees to the barrels.
Whether we export from civil software or we draw the geometric data from scratch, we already consider the geometry with this transition implemented. In other words, the geometric data already contemplates the transition between the shapes of the cross sections I mentioned.
Regarding this situation, we have two questions:
1. Is it necessary to set ineffective flow areas? Our assumption is that manually considering the transition of the cross sections, the flow is actively being conveyed between each XS. Therefore, we should not be considering any ineffective flow areas.
2. What is the entrance loss coefficient that we should use? Should we use the typical 0.4 (wingwalls at 30 to 75 degrees to barrel, square-edge at crown)? Or are we considering twice the contraction of flow, and, therefore, this is not necessary?
Writing this last point in other words, if we use the chart, scale, and entrance loss coefficient of wingwalls flared to the angle we got, should we consider that RAS is doing the transitions for us? We are aware of the rules of cross sections locations when modeling culverts/bridges.
One last thing: we wonder if this situation could be done in a faster way. One example we could think of is representing obstructions to the flow between each cross section and interpolating them. But the interpolation does not seem to work for obstructions (as for ineffective flow areas).
Thanks a lot!