Channel geometry

Compute geometry relations for trapezoidal channels.

channel_geom(y, B, SS)

Arguments

y

Flow depth [\(L\)].

B

Channel bottom width [\(L\)].

SS

Channel sideslope [\(L L^{-1}\)]. For a rectangular channel, SS = 0.

Value

Named vector:

A

Flow area [\(L^2\)].

P

Wetted perimeter [\(L\)].

R

Hydraulic radius [\(L\)].

dAdy

Water surface width [\(L\)].

dPdy

First derivative of wetted perimeter w.r.t. flow depth.

dRdy

First derivative of hydraulic radius w.r.t. flow depth.

DH

Hydraulic depth [\(L\)].

ybar

Vertical distance from water surface to centroid of flow area [\(L\)].

Details

Channel geometry relations are routinely calculated in numerical solutions of steady, gradually-varied and unsteady flows. This function is used extensively by internal procedures and is made accessible to the user for convenience.

Examples

channel_geom(1.71, 100, 0) # rectangular channel
#>           A           P           R        dAdy        dTdy        dPdy 
#> 171.0000000 103.4200000   1.6534519 100.0000000   0.0000000   2.0000000 
#>        dRdy          DH        ybar 
#>   0.9349555   1.7100000   0.8550000 
channel_geom(5.79, 6.1, 1.5) # trapezoidal channel with sideslope 3H:2V
#>          A          P          R       dAdy       dTdy       dPdy       dRdy 
#> 85.6051500 26.9761419  3.1733652 23.4700000  3.0000000  3.6055513  0.4458854 
#>         DH       ybar 
#>  3.6474286  2.3281400