# channel_geom: Channel geometry In rivr: Steady and Unsteady Open-Channel Flow Computation

## Description

Compute geometry relations for trapezoidal channels.

## Usage

 `1` ```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`.

## 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.

## 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].

## Examples

 ```1 2``` ```channel_geom(1.71, 100, 0) # rectangular channel channel_geom(5.79, 6.1, 1.5) # trapezoidal channel with sideslope 3H:2V ```

### Example output

```          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
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
```

rivr documentation built on Jan. 21, 2021, 5:06 p.m.