This section briefly shows some of the results of this case study. For a more extensive overview, one is referred to Verbruggen (2012).
Behaviour of small-amplitude bars
First of all we have investigated how small bars have to be to behave linearly, see left figure. The figure shows that in this case, bars with a bar height of 2% of the water depth are behaving linearly, bars with a larger amplitude show a non-linear process. The figure on the right shows the comparison of the amplification rate of small-amplitude bars (red and blue line) with linear theory (green line). The difference between the red and blue line is the applied numerical scheme for the morphological updating procedure (see page 334 of the Delft3D-FLOW manual). It is beyond the scope of this guideline to explain this more thoroughly, but it is clear that in this case the ‘central’ scheme is more accurate in calculating the amplification rate of small-amplitude bars.
Influence of the bend
When we apply no perturbation at the inflow boundary or at the bed, we see that in super-resonant conditions (see ‘conceptual’ tab) bars are moving in upstream direction, against the flow direction.