HY8:Stilling Basins: Difference between revisions

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The four types of Stilling Basins External Energy Dissipators available in the program:
The four types of Stilling Basins External Energy Dissipators available in the program:


* [[WMS:HY-8 USBR Type III Stilling Basin|USBR Type III Stilling Basin]]
* [[HY8:USBR Type III Stilling Basin|USBR Type III Stilling Basin]]
* [[WMS:HY-8 USBR Type IV Stilling Basin|USBR Type IV Stilling Basin]]
* [[HY8:USBR Type IV Stilling Basin|USBR Type IV Stilling Basin]]
* [[WMS:HY-8 Saint Anthony Falls (SAF Stilling Basin)|St. Anthony Falls (SAF) Stilling Basin]]
* [[HY8:Saint Anthony Falls (SAF Stilling Basin)|St. Anthony Falls (SAF) Stilling Basin]]
 


The maximum width of an efficient 'USBR' type stilling basin is limited by the width that a jet of water would flare naturally on the basin foreslope. The user is given the maximum flare value and is prompted to enter a basin width smaller than this value.  If a 'SAF' basin is used, the basin width is set equal to the culvert width and the user is prompted to choose either a rectangular or flared basin depending on site conditions.  Stilling Basins resemble the following illustration.
The maximum width of an efficient 'USBR' type stilling basin is limited by the width that a jet of water would flare naturally on the basin foreslope. The user is given the maximum flare value and is prompted to enter a basin width smaller than this value.  If a 'SAF' basin is used, the basin width is set equal to the culvert width and the user is prompted to choose either a rectangular or flared basin depending on site conditions.  Stilling Basins resemble the following illustration.
                        
                        
[[Image:HY8image7.jpg]]
:[[Image:HY8-StillingBasin.jpg|500 px]]
 


Variables from the figure
Variables from the figure
* W<sub>0</sub> -- width of the channel
* W<sub>0</sub> &mdash; width of the channel
* W<sub>B</sub> -- Width of the basin
* W<sub>B</sub> &mdash; Width of the basin
* y<sub>0</sub> -- Culvert outlet depth
* y<sub>0</sub> &mdash; Culvert outlet depth
* Y<sub>1</sub> -- Depth entering the basin
* y<sub>1</sub> &mdash; Depth entering the basin
* Y<sub>2</sub> -- Conjugate depth
* y<sub>2</sub> &mdash; Conjugate depth
* S<sub>0</sub> -- Slope of the channel
* S<sub>0</sub> &mdash; Slope of the channel
* S<sub>T</sub> -- Slope of the transition
* S<sub>T</sub> &mdash; Slope of the transition
* S<sub>S</sub> -- Slope leaving the basin
* S<sub>S</sub> &mdash; Slope leaving the basin
* Z<sub>0</sub> -- ground elevation at the culvert outlet
* Z<sub>0</sub> &mdash; ground elevation at the culvert outlet
* Z<sub>1</sub> -- ground elevation at the basin entrance
* Z<sub>1</sub> &mdash; ground elevation at the basin entrance
* Z<sub>2</sub> -- ground elevation at the basin exit
* Z<sub>2</sub> &mdash; ground elevation at the basin exit
* Z<sub>3</sub> -- Elevation of basin at basin exit (sill)
* Z<sub>3</sub> &mdash; Elevation of basin at basin exit (sill)
* L<sub>T</sub> -- Length of transition from culvert outlet to basin
* L<sub>T</sub> &mdash; Length of transition from culvert outlet to basin
* L -- Total basin length
* L &mdash; Total basin length
* L<sub>B</sub> -- Length of the bottom of the basin
* L<sub>B</sub> &mdash; Length of the bottom of the basin
* L<sub>S</sub> -- Length of the basin from the bottom of the basin to the basin exit (sill)
* L<sub>S</sub> &mdash; Length of the basin from the bottom of the basin to the basin exit (sill)
* T<sub>w</sub> -- Tailwater depth leaving the basin
* T<sub>w</sub> &mdash; Tailwater depth leaving the basin
 


== Warning for Stilling Basin Width ==
== Warning for Stilling Basin Width ==
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{{HY8Main}}
{{HY8Main}}
[[Category:Energy Dissipators|S]]

Latest revision as of 14:51, 2 November 2017

The four types of Stilling Basins External Energy Dissipators available in the program:

The maximum width of an efficient 'USBR' type stilling basin is limited by the width that a jet of water would flare naturally on the basin foreslope. The user is given the maximum flare value and is prompted to enter a basin width smaller than this value. If a 'SAF' basin is used, the basin width is set equal to the culvert width and the user is prompted to choose either a rectangular or flared basin depending on site conditions. Stilling Basins resemble the following illustration.

HY8-StillingBasin.jpg

Variables from the figure

  • W0 — width of the channel
  • WB — Width of the basin
  • y0 — Culvert outlet depth
  • y1 — Depth entering the basin
  • y2 — Conjugate depth
  • S0 — Slope of the channel
  • ST — Slope of the transition
  • SS — Slope leaving the basin
  • Z0 — ground elevation at the culvert outlet
  • Z1 — ground elevation at the basin entrance
  • Z2 — ground elevation at the basin exit
  • Z3 — Elevation of basin at basin exit (sill)
  • LT — Length of transition from culvert outlet to basin
  • L — Total basin length
  • LB — Length of the bottom of the basin
  • LS — Length of the basin from the bottom of the basin to the basin exit (sill)
  • Tw — Tailwater depth leaving the basin

Warning for Stilling Basin Width

Since the maximum basin width is a function of basin depth, the maximum width may decrease as the program increases the basin depth while converging on a solution. Therefore the maximum basin width may fall below the user's first choice for basin width. In this case, the user will be prompted for a new basin width.