Contraction\expansion coefficients

[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

[MattZ]

The momentum equation (used for unsteady flow calcs) integrates forces acting over the surfaces and end of the control volume and the impacts of flow expansions/contractions are captured in the forces on the upstream and downstream ends of that control volume. Thus, the C/E coefficients are not used.

Unsteady flow calcs at structures are done using the results of the geometry pre-processor. You could run the pre-processor by itself to develop a family of curves for your bridges and culverts.