contraction\expansion losses

[GEI]

Hello,
For an unsteady analysis, are the contraction\expansion coefficients used ? I think no, but how are computed the losses between two sections, or for a bridge ?
My problem is I need to calculate the dimensions of bridges and culverts for a highway, with an unsteady analysis. So, the contraction\expansion losses are very important. Should I use only culvert structures (I can control easily C\E coeff.) ?
Thank you for your answers

LP

[jarvus lunt]

Expansion and contraction are not used for unsteady flow. The unsteady flow solution is based on momentum.

However, bridge and culverts are preprocessed using steady flow to create a family of rating curves (so that the unsteady flow program can run faster). So I have the impression that the contraction and expansion is taken into account at bridges and culverts.

If you haven't already, download the RAS hydraulic reference manual. There is a wealth of information in it about how RAS does the computations (if you want to spend the time reading it all).