pyts.stressModels package

Submodules

pyts.stressModels.api module

PyTurbSim ‘Reynold’s stress models’ package.

The Reynold’s stress quantifies correlations betweens turbulent velocity components. It has three components: <u’v’>, <u’w’> and <v’w’> (‘<x>’ denotes an ‘appropriate’ time average of the quantity ‘x’).

Available stress models:

main.uniform (alias: uniform)

A uniform Reynold’s stress over the spatial domain.

hydro.tidal (alias: tidal)

The ‘tidal` Reynold’s stress model (increases linearly toward the seafloor/ground).

stressModelBase

This is the base class for stress models. To create a new one, subclass this class or subclass and modify an existing stress model.

stressObj

This is the ‘stress object’ class. All stress model __call__ methods must take a tsrun as input and return this class.

Example usage

import pyts.stressmodels.api as rm

Create a uniform Reynold’s stress model where each component is specified explicitly:

>>> my_stress_model=rm.uniform(upvp_=0.01,upwp_=0.1,vpwp_=0.0)

This stress model can then be applied to a tsrun (see pyts.main.tsrun):

>>> tsrun.stress=my_stress_model(tsrun)

See also

For a description of the difference between ‘stress models’ (e.g. ‘my_stress_model’ in example above) and the stress they output (tsrun.prof), see the ‘models_and_stats_example.py’ file.

pyts.stressModels.base module

This is the stress package’s base module.

produce estimates of Reynold’s stress

class pyts.stressModels.base.stressModelBase

Bases: pyts.base.modelBase

class pyts.stressModels.base.stressObj(tsrun)

Bases: pyts.base.calcObj, pyts.base.gridProps

calc_phases(phases)

Here we control the Reynold’s stress by setting the phases between components to be the same for a fraction of the frequencies.

check_validity()

Check that the Reynold’s stress magnitudes are valid.

corr

upvp_

The u’v’ Reynolds stress for this model.

upvp_max

The product of the standard deviations of u’ and v’ (i.e. the maximum stress for the given turbulence model).

upwp_

The u’w’ Reynolds stress for this model.

upwp_max

The product of the standard deviations of u’ and w’ (i.e. the maximum stress for the given turbulence model).

validity

Return a validity array for the stress magnitudes.

Returns:

A 3 x n_z x n_y boolean array.

There are three criteria for each point in the grid. They are

listed here by their index in the array:

0. The magnitude criteria: no stress can exceed the maximum stress (correlation between components cannot exceed 1).
1. The ‘overlap’ criteria: The sum of the magnitude of the correlations can exceed one if they overlap. However, their are limits to the overlap. This criteria indicates that limit has been exceeded.
2. The ‘sign’ criteria. If only one component is negative than they can not overlap. In this case the sum of magnitude of the correlations must be less than 1.

If any of the criteria are false at any point, than the

stressModel is invalid at that point.

vpwp_

The v’w’ Reynolds stress for this model.

vpwp_max

The product of the standard deviations of v’ and w’ (i.e. the maximum stress for the given turbulence model).

pyts.stressModels.hydro module

class pyts.stressModels.hydro.tidal(Ustar, Zref)

Bases: pyts.stressModels.base.stressModelBase

The ‘tidal’ model Reynold’s stress model.

Parameters:

Ustar : float

The friction velocity at the bottom boundary (aka \(U_*\)).

Zref : float

The height of the ‘no-stress’ level in the water-column.

Notes

The v’w’ and u’v’ components are zero. The u’w’ component is:

\[\overline{u'w'} = -U_*^2 (1-z/Z_{\mathrm{ref}})\]

for 0<z<Zref, and 0 elsewhere.

__call__(tsrun)

Create and calculate the stress object for a tsrun instance.

Parameters:

tsrun : tsrun

A TurbSim run object.

Returns:

out : stressObj

A stress object for the grid in tsrun.

pyts.stressModels.main module

class pyts.stressModels.main.uniform(upvp_=0.0, upwp_=0.0, vpwp_=0.0)

Bases: pyts.stressModels.base.stressModelBase

Uniform Reynold’s stress model.

In this model each component of the Reynold’s stress can be specified explicitly, but the values are uniform in space.

Parameters:

upvp_ : float

The u’v’ component of Reynold’s stress.

upwp_ : float

The u’w’ component of Reynold’s stress.

vpwp_ : float

The v’w’ component of Reynold’s stress.

__call__(tsrun)

Create and calculate the stress object for a tsrun instance.

Parameters:

tsrun : tsrun

A TurbSim run object.

Returns:

out : stressObj

A stress object for the grid in tsrun.

pyts.stressModels.stress_freq module

class pyts.stressModels.stress_freq.stressModelBase_f

Bases: pyts.stressModels.base.stressModelBase

A stress-model base-class that supports setting the stress by controlling the frequency-dependent coherence between velocity components.

Module contents

This is the PyTurbSim ‘stress models’ package.

For more information or to use this package import the stressModels.api package, e.g.:

>>> import pyts.stressModels.api as rm

Currently the stress package does not function properly, unless no coherence is used. Fixing this is near the top of the list of things to repair in PyTurbSim.