Time and length scales of turbulence - Revision history

CynthiaBluteau: /* Low wavenumber limit */

2022-07-07T13:21:31Z

Low wavenumber limit

← Older revision		Revision as of 13:21, 7 July 2022
Line 17:		Line 17:

	=== Low wavenumber limit ===		=== Low wavenumber limit ===
	Of the order of the largest ~~eddy~~ sizes...		Of the order of the largest overturn sizes...
	* Stratified waters Lo		* Stratified waters Lo
	* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.		* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.

CynthiaBluteau at 20:34, 1 December 2021

2021-12-01T20:34:17Z

← Older revision		Revision as of 20:34, 1 December 2021
Line 7:		Line 7:
	* [[Detrending time series]]		* [[Detrending time series]]

			==Lengthscales==
	[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]		[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]


	~~==Lengthscales==~~
	'''Add links to correct pages'''		'''Add links to correct pages'''
	=== High wavenumber limit===		=== High wavenumber limit===

CynthiaBluteau at 20:33, 1 December 2021

2021-12-01T20:33:52Z

← Older revision		Revision as of 20:33, 1 December 2021
Line 6:		Line 6:
	* [[Segmenting datasets]]		* [[Segmenting datasets]]
	* [[Detrending time series]]		* [[Detrending time series]]

	~~==Timescales==~~
	~~Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite turbulent length scale. In stratified waters, this amounts to 1/N.~~

	[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]		[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]
Line 25:		Line 22:
	* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.		* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.
	* Sheared flows can also swap Lo with Ls (Corrsin). Ls = Lz in a pure log-law of the wall flow!		* Sheared flows can also swap Lo with Ls (Corrsin). Ls = Lz in a pure log-law of the wall flow!

			==Timescales==
			Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite turbulent length scale. In stratified waters, this amounts to 1/N.

CynthiaBluteau at 20:32, 1 December 2021

2021-12-01T20:32:17Z

← Older revision		Revision as of 20:32, 1 December 2021
Line 6:		Line 6:
	* [[Segmenting datasets]]		* [[Segmenting datasets]]
	* [[Detrending time series]]		* [[Detrending time series]]

			==Timescales==
			Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite turbulent length scale. In stratified waters, this amounts to 1/N.

	[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]		[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]

	~~==Timescales==~~
	~~Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite turbulent length scale. In stratified waters, this amounts to 1/N.~~

	==Lengthscales==		==Lengthscales==

CynthiaBluteau at 20:31, 1 December 2021

2021-12-01T20:31:46Z

← Older revision		Revision as of 20:31, 1 December 2021
Line 9:		Line 9:
	[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]		[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]

	== High wavenumber limit==		==Timescales==
			Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite turbulent length scale. In stratified waters, this amounts to 1/N.

			==Lengthscales==
			'''Add links to correct pages'''
			=== High wavenumber limit===
	For instance, the wavenumber (length scale) limits depend on the sought quantity <math>\varepsilon</math>, and also the kinematic viscosity <math>\nu</math>:		For instance, the wavenumber (length scale) limits depend on the sought quantity <math>\varepsilon</math>, and also the kinematic viscosity <math>\nu</math>:

	<math>L_K=\left(\frac{\nu^3}{\varepsilon}\right)^{1/4}</math>		<math>L_K=\left(\frac{\nu^3}{\varepsilon}\right)^{1/4}</math>

	== Low wavenumber limit ==		=== Low wavenumber limit ===
	Of the order of the largest eddy sizes...		Of the order of the largest eddy sizes...
	* Stratified waters Lo		* Stratified waters Lo
	* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.		* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.
	* Sheared flows can also swap Lo with Ls (Corrsin). Ls = Lz in a pure log-law of the wall flow!		* Sheared flows can also swap Lo with Ls (Corrsin). Ls = Lz in a pure log-law of the wall flow!

	~~== Timescales ==~~
	~~Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite L.~~

CynthiaBluteau: Categorising page as processing page, although it could be a concept page

2021-12-01T20:29:29Z

Categorising page as processing page, although it could be a concept page

← Older revision		Revision as of 20:29, 1 December 2021
Line 1:		Line 1:
	{{ADV processing		{{ADV processing
	\|instrument_type=ADV		\|instrument_type=ADV
	\|level=level 1 raw		\|level=level 1 raw, level 2 segmented and quality controlled, level 3 spectra
	}}		}}

	The length and time scales of turbulence must be considered when analysing turbulence measurements. The scales at which the turbulence subranges, both the viscous and inertial subrange, exist depend on the flow properties. These characteristics of the flow influence various decisions when processing velocity measurements for turbulence computations such as:		The length and time scales of turbulence must be considered when analysing turbulence measurements. The scales at which the turbulence subranges, both the viscous and inertial subrange, exist depend on the flow properties. These characteristics of the flow influence various decisions when processing velocity measurements for turbulence computations such as:
	* [[Segmenting datasets]]		* [[Segmenting datasets]]

CynthiaBluteau: Added links to velocity processing.

2021-12-01T20:28:37Z

Added links to velocity processing.

← Older revision		Revision as of 20:28, 1 December 2021
Line 1:		Line 1:
	The length and time scales of turbulence must be considered when analysing turbulence measurements. The scales at which the turbulence subranges, both the viscous and inertial subrange, exist depend on the flow properties.		{{ADV processing
			\|instrument_type=ADV
			\|level=level 1 raw
			}}

	[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min.]]		The length and time scales of turbulence must be considered when analysing turbulence measurements. The scales at which the turbulence subranges, both the viscous and inertial subrange, exist depend on the flow properties. These characteristics of the flow influence various decisions when processing velocity measurements for turbulence computations such as:
			* [[Segmenting datasets]]
			* [[Detrending time series]]

			[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min. Turbulence analysis is concerned with time scales larger than the buoyancy period]]

	== High wavenumber limit==		== High wavenumber limit==

CynthiaBluteau: /* Timescales */

2021-12-01T18:57:44Z

Timescales

← Older revision		Revision as of 18:57, 1 December 2021
Line 15:		Line 15:

	== Timescales ==		== Timescales ==
	Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math>		Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math> and dump your favourite L.

CynthiaBluteau: Draft material

2021-12-01T18:54:25Z

Draft material

← Older revision		Revision as of 18:54, 1 December 2021
Line 4:		Line 4:

	== High wavenumber limit==		== High wavenumber limit==
	For instance, the wavenumber (length scale) limits depend on the sought quantity <math>\varepsilon</math>, and also the kinematic viscosity.		For instance, the wavenumber (length scale) limits depend on the sought quantity <math>\varepsilon</math>, and also the kinematic viscosity <math>\nu</math>:

			<math>L_K=\left(\frac{\nu^3}{\varepsilon}\right)^{1/4}</math>

	== Low wavenumber limit ==		== Low wavenumber limit ==
			Of the order of the largest eddy sizes...
			* Stratified waters Lo
			* Near a boundary <math>L_Z=0.39z_w</math> via von karman's constant of 0.39 and zw the distance to said boundary.
			* Sheared flows can also swap Lo with Ls (Corrsin). Ls = Lz in a pure log-law of the wall flow!

	== Timescales ==		== Timescales ==
	Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math>		Can use the equation <math>\tau=(L^2/\varepsilon)^{1/3}</math>

CynthiaBluteau: Added sketch

2021-12-01T18:44:11Z

Added sketch

← Older revision		Revision as of 18:44, 1 December 2021
Line 1:		Line 1:
	The length and time scales of turbulence must be considered when analysing turbulence measurements. The scales at which the turbulence subranges, both the viscous and inertial subrange, exist depend on the flow properties.		The length and time scales of turbulence must be considered when analysing turbulence measurements. The scales at which the turbulence subranges, both the viscous and inertial subrange, exist depend on the flow properties.

			[[File:Velocity timescales.png\|400px\|thumb\|Example velocities from an instrument impacted by tides and surface waves, which are presented as variance preserving spectra. The instrument is tens of meters off the bottom on the continental shelf in stratified waters with a buoyancy period of 9 min.]]

	== High wavenumber limit==		== High wavenumber limit==