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: | ||
* [[ | * [[HY8:USBR Type III Stilling Basin|USBR Type III Stilling Basin]] | ||
* [[ | * [[HY8:USBR Type IV Stilling Basin|USBR Type IV 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: | :[[Image:HY8-StillingBasin.jpg|500 px]] | ||
Variables from the figure | Variables from the figure | ||
* W<sub>0</sub> | * W<sub>0</sub> — width of the channel | ||
* W<sub>B</sub> | * W<sub>B</sub> — Width of the basin | ||
* y<sub>0</sub> | * y<sub>0</sub> — Culvert outlet depth | ||
* y<sub>1</sub> | * y<sub>1</sub> — Depth entering the basin | ||
* y<sub>2</sub> | * y<sub>2</sub> — Conjugate depth | ||
* S<sub>0</sub> | * S<sub>0</sub> — Slope of the channel | ||
* S<sub>T</sub> | * S<sub>T</sub> — Slope of the transition | ||
* S<sub>S</sub> | * S<sub>S</sub> — Slope leaving the basin | ||
* Z<sub>0</sub> | * Z<sub>0</sub> — ground elevation at the culvert outlet | ||
* Z<sub>1</sub> | * Z<sub>1</sub> — ground elevation at the basin entrance | ||
* Z<sub>2</sub> | * Z<sub>2</sub> — ground elevation at the basin exit | ||
* Z<sub>3</sub> | * Z<sub>3</sub> — Elevation of basin at basin exit (sill) | ||
* L<sub>T</sub> | * L<sub>T</sub> — Length of transition from culvert outlet to basin | ||
* L | * L — Total basin length | ||
* L<sub>B</sub> | * L<sub>B</sub> — Length of the bottom of the basin | ||
* L<sub>S</sub> | * L<sub>S</sub> — Length of the basin from the bottom of the basin to the basin exit (sill) | ||
* T<sub>w</sub> | * T<sub>w</sub> — 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.
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.
