Information about the Vertical Velocity Profile - Revision history

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2022-10-21T09:30:53Z

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← Older revision		Revision as of 09:30, 21 October 2022
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	==Information about the Vertical Velocity Profile==		==Information about the Vertical Velocity Profile==

	This applet displays a vertical and logarithmical profile of current velocity in an infinitely wide channel.		This applet displays a vertical and logarithmical profile of current velocity in an infinitely wide [[channel]].
	A watercolumn is divided into several horizontal layers. The applet calculates for each layer a horizontal velocity v which is a function of z, the height of each layer relative to the bottom.		A watercolumn is divided into several horizontal layers. The applet calculates for each layer a horizontal velocity v which is a function of z, the height of each layer relative to the bottom.

	==Input measures==		==Input measures==
	Bottom Gradient and Water Depth do not need any explanation.		Bottom [[Gradient]] and [[Water depth\|Water Depth]] do not need any explanation.

	* The Strickler Value defines the bottom shear stress. A higher value stands for a lower stress.		* The Strickler Value defines the bottom [[shear stress]]. A higher value stands for a lower stress.
	:Examples:		:Examples:
	:sand (Elbe and Weser Estuary): approx. 48 m(1/3) s(-1/2)		:sand (Elbe and Weser [[Estuary]]): approx. 48 m(1/3) s(-1/2)
	:wild creek with rubble: approx. 20 m(1/3) s(-1/2)		:wild creek with rubble: approx. 20 m(1/3) s(-1/2)
	* deltaZ: The watercolumn is divided into several horizontal layers. The user specifies the vertical distance between neighboured layers via the input field deltaZ. For a correct graphical display deltaZ should be smaller than the Log Law's Z0 value.		* deltaZ: The watercolumn is divided into several horizontal layers. The user specifies the vertical distance between neighboured layers via the input field deltaZ. For a correct graphical display deltaZ should be smaller than the Log Law's Z0 value.
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	==Output measures==		==Output measures==

	* In this model there is a layer directly above the bottom where the velocity is zero. Log Law's Z0 is the height of this layer. Log Law's Z0 depends on Water Depth and Strickler Value.		* In this [[model]] there is a layer directly above the bottom where the velocity is zero. Log Law's Z0 is the height of this layer. Log Law's Z0 depends on [[Water depth\|Water Depth]] and Strickler Value.
	* V(H) shows the velocity at the water surface.		* V(H) shows the velocity at the [[water surface]].
	* V DepthAveraged stands for the depth-averaged velocity. The calculation of the average includes the layers with v=0 m/s as well as the layers with v>0 m/s. The calculation is more accurate by using smaller values of deltaZ.		* V DepthAveraged stands for the depth-averaged velocity. The calculation of the average includes the layers with v=0 m/s as well as the layers with v>0 m/s. The calculation is more accurate by using smaller values of deltaZ.
	* The result field at the lower right corner of the applet displays a line with pairs (velocity v and height relative to the bottom z)		* The result field at the lower right corner of the applet displays a line with pairs (velocity v and height relative to the bottom z)

imported>Spohr Susanne at 12:00, 5 October 2010

2010-10-05T12:00:43Z

← Older revision		Revision as of 12:00, 5 October 2010
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			[[de: Information about the Vertical Velocity Profile]]
	Author: [mailto:peter.schade@baw.de P. Schade]		Author: [mailto:peter.schade@baw.de P. Schade]

imported>Spohr Susanne at 11:38, 26 July 2010

2010-07-26T11:38:03Z

← Older revision		Revision as of 11:38, 26 July 2010
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	Calculation of the horizontal velocity v		Calculation of the horizontal velocity v

	v = sqrt(g * WaterDepth * BottomGradient) / Kappa * ln(z/z0)		* v = sqrt(g * WaterDepth * BottomGradient) / Kappa * ln(z/z0)

	g = 9.81 m/s: gravity		* g = 9.81 m/s: gravity
	Kappa = 0.41: Karman constant		* Kappa = 0.41: Karman constant
	z0 : zero Level of the logarithmic law with		* z0 : zero Level of the logarithmic law with

	z0 = (12./30.WaterDepth) / 10(StricklerValue WaterDepth**(1/6) / 18))		* z0 = (12./30.WaterDepth) / 10(StricklerValue WaterDepth**(1/6) / 18))

	The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.		The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.

imported>Spohr Susanne at 11:20, 26 July 2010

2010-07-26T11:20:24Z

← Older revision		Revision as of 11:20, 26 July 2010
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			Author: [mailto:peter.schade@baw.de P. Schade]

	==Information about the Vertical Velocity Profile==		==Information about the Vertical Velocity Profile==

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	The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.		The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.
	----		----
	back to [[Vertical Velocity Profile]]		back to [[Vertical Velocity Profile\|Applet]]
	----		----
	[[Overview]]		[[Overview]]

imported>BAWiki 3 at 13:38, 1 July 2010

2010-07-01T13:38:03Z

← Older revision		Revision as of 13:38, 1 July 2010
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	The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.		The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.
			----
			back to [[Vertical Velocity Profile]]
			----
			[[Overview]]

imported>BAWiki 3 at 10:55, 1 July 2010

2010-07-01T10:55:04Z

← Older revision		Revision as of 10:55, 1 July 2010
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	z0 = (12./30.WaterDepth) / 10(StricklerValue WaterDepth**(1/6) / 18))		z0 = (12./30.WaterDepth) / 10(StricklerValue WaterDepth**(1/6) / 18))

	The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.		The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.

	~~----~~
	~~[[Overview]]~~

imported>BAWiki 3: Created page with '==Information about the Vertical Velocity Profile== This applet displays a vertical and logarithmical profile of current velocity in an infinitely wide channel. A watercolumn is…'

2010-07-01T10:16:13Z

Created page with '==Information about the Vertical Velocity Profile== This applet displays a vertical and logarithmical profile of current velocity in an infinitely wide channel. A watercolumn is…'

New page

==Information about the Vertical Velocity Profile==

This applet displays a vertical and logarithmical profile of current velocity in an infinitely wide channel.
A watercolumn is divided into several horizontal layers. The applet calculates for each layer a horizontal velocity v which is a function of z, the height of each layer relative to the bottom.

==Input measures==
Bottom Gradient and Water Depth do not need any explanation.

* The Strickler Value defines the bottom shear stress. A higher value stands for a lower stress.
:Examples:
:sand (Elbe and Weser Estuary): approx. 48 m**(1/3) s**(-1/2)
:wild creek with rubble: approx. 20 m**(1/3) s**(-1/2)
* deltaZ: The watercolumn is divided into several horizontal layers. The user specifies the vertical distance between neighboured layers via the input field deltaZ. For a correct graphical display deltaZ should be smaller than the Log Law's Z0 value.

==Output measures==

* In this model there is a layer directly above the bottom where the velocity is zero. Log Law's Z0 is the height of this layer. Log Law's Z0 depends on Water Depth and Strickler Value.
* V(H) shows the velocity at the water surface.
* V DepthAveraged stands for the depth-averaged velocity. The calculation of the average includes the layers with v=0 m/s as well as the layers with v>0 m/s. The calculation is more accurate by using smaller values of deltaZ.
* The result field at the lower right corner of the applet displays a line with pairs (velocity v and height relative to the bottom z)

==Physics==

Calculation of the horizontal velocity v

v = sqrt(g * WaterDepth * BottomGradient) / Kappa * ln(z/z0)

g = 9.81 m/s: gravity
Kappa = 0.41: Karman constant
z0 : zero Level of the logarithmic law with

z0 = (12./30.*WaterDepth) / 10**(StricklerValue * WaterDepth**(1/6) / 18))

The user should consider that this profile is only an approximation. Especially near the bottom the formula simplifies a little bit.

----
[[Overview]]