swiift.lib.phase_shift

Pseudo-scattering parameterisations.

Classes

ContinuousScatteringHandler

No scattering.

UniformScatteringHandler

Scattering with uniformly sampled new phases.

PerturbationScatteringHandler

Scattering with phases perturbated around the continuous solution.

Module Contents

class swiift.lib.phase_shift.ContinuousScatteringHandler

Bases: _ScatteringHandler

No scattering.

The surface stays continuous across floes edges.

compute_edge_amplitudes(edge_amplitudes, c_wavenumbers, xf)

Determine post-breakup wave amplitudes at the edge of new floes.

The wave propagates and is attenuated underneath the floe. For the current timestep, for each wave component, the complex wave amplitude is fully determined at all the coordinates where fracture is about to occur. After fractures have occured, the complex amplitudes at these coordinates become the complex amplitudes at the left edges of new fragments. Further pseudo-scattering rules can be used if it is not desirable to keep the wave surface in phase on both sides of a floe edge.

Parameters:

  • edge_amplitudes (np.ndarray of complex) – The complex wave amplitudes at the edge of a breaking floe, in m

  • c_wavenumbers (np.ndarray of complex) – The complex wavenumbers stressing the floe, in m^-1

  • xf (np.ndarray of float) – The coordinates of fractures, in m

Return type:

np.ndarray of complex

class swiift.lib.phase_shift.UniformScatteringHandler

Bases: _RandomScatteringHandler

Scattering with uniformly sampled new phases.

The wave phase at the edge of a new floe is sampled from the uniform distribution on \([0; 2\pi)\).

Parameters:

rng (numpy.random.Generator) – Random generator used to sample phases

classmethod from_seed(seed)

Instantiate self with an RNG seeded by an integer.

Parameters:

seed (int) – A seed passed to numpy.random.default_rng

Return type:

UniformScatteringHandler

compute_edge_amplitudes(edge_amplitudes, c_wavenumbers, xf)

Determine post-breakup wave amplitudes at the edge of new floes.

The wave propagates and is attenuated underneath the floe. For the current timestep, for each wave component, the complex wave amplitude is fully determined at all the coordinates where fracture is about to occur. After fractures have occured, the complex amplitudes at these coordinates become the complex amplitudes at the left edges of new fragments. Further pseudo-scattering rules can be used if it is not desirable to keep the wave surface in phase on both sides of a floe edge.

Parameters:

  • edge_amplitudes (np.ndarray of complex) – The complex wave amplitudes at the edge of a breaking floe, in m

  • c_wavenumbers (np.ndarray of complex) – The complex wavenumbers stressing the floe, in m^-1

  • xf (np.ndarray of float) – The coordinates of fractures, in m

Return type:

np.ndarray of complex

class swiift.lib.phase_shift.PerturbationScatteringHandler

Bases: _RandomScatteringHandler

Scattering with phases perturbated around the continuous solution.

The wave phase at the left edge of a new floe is computed to maintain continuity of the surface across the edge. Then, a random perturbation sampled from a normal distribution, is added to the phase.

rng

Random generator used to sample perturbations

Type:

numpy.random.Generator

loc

The mean of the normal distribution used to sample perturbations, in rad

Type:

float

scale

The standard deviation of the normal distribution used to sample perturbations, in rad

Type:

float

Notes

Perturbations are always added to an existing phase. The expectation of the resulting phase is thus the sum of loc and the phase of the continuous solution.

classmethod from_seed(seed, loc=0, scale=1)

Instantiate with an RNG seeded with an integer.

Parameters:

  • seed (int) – A seed passed to numpy.random.default_rng

  • loc (float) – Mean of a normal distribution, in rad

  • scale (float) – Standard deviation of a normal distribution, in rad

Return type:

PerturbationScatteringHandler

compute_edge_amplitudes(edge_amplitudes, c_wavenumbers, xf)

Determine post-breakup wave amplitudes at the edge of new floes.

The wave propagates and is attenuated underneath the floe. For the current timestep, for each wave component, the complex wave amplitude is fully determined at all the coordinates where fracture is about to occur. After fractures have occured, the complex amplitudes at these coordinates become the complex amplitudes at the left edges of new fragments. Further pseudo-scattering rules can be used if it is not desirable to keep the wave surface in phase on both sides of a floe edge.

Parameters:

  • edge_amplitudes (np.ndarray of complex) – The complex wave amplitudes at the edge of a breaking floe, in m

  • c_wavenumbers (np.ndarray of complex) – The complex wavenumbers stressing the floe, in m^-1

  • xf (np.ndarray of float) – The coordinates of fractures, in m

Return type:

np.ndarray of complex