Nomenclature: Difference between revisions
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! Units | ! Units | ||
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| | | T_N | ||
| <math>\tau_N</math> | | <math>\tau_N</math> | ||
| Buoyancy timescale | | Buoyancy timescale | ||
Revision as of 12:29, 1 April 2021
Frame of reference
- Define frame of reference, and notation. Use u,v,w and x,y, and z?
- Dumping a sketch would be useful
| Parameter name | Symbol | Description | Standard long name | Units |
|---|---|---|---|---|
| EAST_VEL | <math> u </math> | zonal velocity | eastward_velocity | m s-1 |
| NORTH_VEL | <math> v </math> | meridional velocity | northward_velocity | m s-1 |
| UP_VEL | <math> W </math> | vertical velocity | upward_velocity | m s-1 |
| ERROR_VEL | <math> u </math> | error velocity | error_velocity | m s-1 |
| U_VEL | <math> U </math> | velocity parellel to mean flow | meanflow_velocity | m s-1 |
| V_VEL | <math> V </math> | velocity perpendicular to mean flow | crossflow_velocity | m s-1 |
| Drop_Speed | <math> W_d </math> | Profiler fall speed | mean_drop_speed | m s-1 |
| FlowPast_Speed | <math> U_fp </math> | Flow speed past sensor | mean_velocity_past_turbulence_sensor | m s-1 |
Reynold's Decomposition
- Variable names for Decomposition of total, mean, turbulent and waves.
Turbulence properties
| Parameter name | Symbol | Description | Standard long name | Eqn | Units |
|---|---|---|---|---|---|
| EPSI | <math>\epsilon</math> | Turbulent kinetic energy dissipation | tke_dissipation | W/kg | |
| RI | <math>Ri</math> | Richardson number | richardson_number | <math> Ri = \frac{N^2}{S^2}</math> | |
| RI_F | <math>Ri_f</math> | Flux gradient Richardson number | flux_grad_richardson_number | <math> \frac{B}{P} </math> or Ivey & Immerger? | |
| Krho | <math>\kappa_\rho</math> | Turbulent diffusivity | turbulent_diffusivity | <math> \kappa = \Gamma \epsilon N^{-2} </math> | m<math>^2</math>s<math>^{-1}</math> |
Fluid properties and background gradients for turbulence calculations
| Parameter Name | Symbol | Description | Standard long name | Eqn | Units |
|---|---|---|---|---|---|
| S | <math>S</math> | Background velocity shear | background_velocity_shear | U|}{\partial z}</math> | s<math>^{-1}</math> |
| KVISC35 | <math>\nu</math> | Kinematic viscosity of water for seawater at 35 and 20 <math>^o</math>C | seawater_kinematic_viscosity_at_35psu | <math> 1\times 10^{-6}</math> | m2/s |
| N | <math>N</math> | Background stratification, i.e buoyancy frequency | background_buoyancy_frequency | <math> N = \sqrt{\frac{-g}{\bar{\rho}} \frac{\partial\bar{\rho}}{\partial z}}</math> | rad/s |
Theoretical Length and Time Scales
| Parameter | Symbol | Description | Standard long name | Eqn | Units |
|---|---|---|---|---|---|
| T_N | <math>\tau_N</math> | Buoyancy timescale | buoyancy_time_scale | <math> \tau_N = \frac{2\pi}{N}</math> | s |
| L_E | <math>L_E</math> | Ellison length scale (limit of vertical displacement without irreversible mixing) | Eliison_lenght_scale | <math>L_E=\frac {\langle \rho'^2\rangle^{1/2}}{\partial \overline{\rho}/\partial z}</math> | m |
| L_RHO | <math> L_\rho</math> | Density length scale | density_length_scale | <math> L_\rho </math> | m |
| L_S | <math>L_S</math> | Corssin length scale | Corssin_shear_length_scale | <math> L_S = \sqrt{\epsilon/S^3} </math> | m |
| L_K | <math>\eta</math> | Kolmogorov length scale (smallest overturns) | Kolmogorov_length_scale | <math>\eta=\left(\frac{\nu^3}{\epsilon}\right)^{1/4}=\frac{1}{2\pi\hat{k}_K}</math> | m |
| L_O | <math>L_o</math> | Ozmidov length scale, measure of largest overturns in a stratified fluid | Ozmidov_stratification_length_scale | <math>L_o=\left(\frac{\epsilon}{N^3}\right)^{1/2}</math> | m |
| L_T | <math>L_T</math> | Thorp length scale | Thorpe_stratification_length_scale | <math>L_T</math> | m |
Turbulence Spectrum
Taylor's Frozen Turbulence for converting temporal to spatial measurements <math>\left(\bar{u}_1\frac{\partial }{\partial{x}} = \frac{\partial}{\partial{t}}\right)</math>
- Missing the y-axi variable. CEB proposes:
- <math>\Psi_{variable}</math> for model/theoretical spectrum of variable e.g., du/dx or u
- <math>\Phi_{variable}</math> for observed spectrum of variable e.g., du/dx or u
- Lowest frequency and wavenumber resolvable
| Symbol | Description | Eqn | Units |
|---|---|---|---|
| <math>\Delta t</math> | Sampling interval | <math> \frac{1}{f_s} </math> | s |
| <math>\Delta s</math> | Sampling volume dimension | m | |
| <math>f</math> | Frequency | <math>\frac{\omega}{2\pi}</math> | Hz |
| <math>f_n</math> | Nyquist frequency | <math>f_n=0.5f_s</math> | Hz |
| <math>f_s</math> | Sampling frequency | <math>f_s=\frac{1}{\Delta t} </math> | Hz |
| <math>k</math> | Wavenumbers (angular) | <math>k=\frac{f}{\bar{u}}=2\pi\hat{k}</math> | rad/m |
| <math>\hat{k}</math> | Wavenumbers | <math>\hat{k}=\frac{k}{2\pi}</math> | cpm |
| <math>\hat{k}_\Delta</math> | Nyquist wavenumber, based on sampling volume's size <math>\Delta l</math> | <math>\hat{k}_\Delta=\frac{0.5}{\Delta l}</math> | cpm |
| <math>\hat{k}_n</math> | Nyquist wavenumber, via Taylor's hypothesis (temporal measurements) | <math>\hat{k}_n=\frac{f_n}{u}</math> | cpm |
| <math>\omega</math> | Angular frequency | <math>2\pi f</math> | rad/s |
