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API for SphericalChunk3DSurfaceWaves type meshes

Salvus version: 0.11.23

This document describes all the various parameters and settings for meshes of the SphericalChunk3DSurfaceWaves type available when using the simple_mesh interface of SalvusMesh:

Copy
from salvus.mesh import simple_mesh
m = simple_mesh.SphericalChunk3DSurfaceWaves(...)
# Accessing the elements_per_wavelength parameter in the basic group
m.basic.elements_per_wavelength = 2.0

Basic Parameters group [basic]

The most important parameters for Surface Wave Meshes (EXPERIMENTAL).

Required: True

Detailed description of all parameters:

  • model

    • Pretty name: 1D Model

    • Description: Model Name for predefined 1D models or filename for external 1D model file.

    • Parameter type: string

    • Required: True

  • elements_per_wavelength

    • Pretty name: Elements per Wavelength

    • Description: Number of elements per wavelength at the mimimum period. Used to calculate element sizes in the 1D model as a function of depth.

    • Parameter type: number

    • Required: True

  • nelem_vertical

    • Pretty name: Number of elements in vertical direction

    • Description: Number of elements in vertical direction in each layer in the background model, starting from the top

    • Parameter type: array of integers

    • Required: False

  • lmax_at_discontinuities

    • Pretty name: Maximum angular order at all discontinuities in the model

    • Description: Maximum angular order at all discontinuities in the model

    • Parameter type: array of integers

    • Required: True

    • Default: [32, 32]

  • max_nrefine

    • Pretty name: Maximum number of horizontal refinements

    • Description: Maximum number of horizontal refinements

    • Parameter type: integer

    • Required: True

    • Default: 3

Advanced Parameters group [advanced]

Advanced parameters for more control on seismic wave sisimulation meshes.

Required: True

Detailed description of all parameters:

  • courant_number

    • Pretty name: Courant Number

    • Description: Courant Number used to estimate dt.

    • Parameter type: number

    • Required: True

    • Default: 0.6

  • tensor_order

    • Pretty name: Tensor Order

    • Description: Spatial order used for shape mapping and model representation.

    • Parameter type: integer

    • Required: True

    • Default: 1

  • model_parameters

    • Pretty name: Model Parameters

    • Description: Model parameters to put into the mesh, defaults to the parametrization used by the 1D background model. This can be used for example to create an anisotropic parametrization of an isotropic model.

    • Parameter type: array of strings

    • Required: False

    • Default: []

    • Possible values: "g", "dg", "VP", "VS", "VSV", "VSH", "VPV", "VPH", "RHO", "QMU", "QKAPPA", "C11", "C12", "C13", "C14", "C15", "C16", "C21", "C22", "C23", "C24", "C25", "C26", "C31", "C32", "C33", "C34", "C35", "C36", "C41", "C42", "C43", "C44", "C45", "C46", "C51", "C52", "C53", "C54", "C55", "C56", "C61", "C62", "C63", "C64", "C65", "C66", "A", "C", "L", "N", "F", "XI", "PHI", "LAMBDA", "MU", "KAPPA", "ETA"

  • velocity_model_representation

    • Pretty name: Velocity Model Representation

    • Description: How to represent the velocity model on the mesh. element_nodes: values are stored on each node of each element, allows discontinuities and variations inside each element, but produces large files. elements: one value per element, allows discontinuities but the model will be piecewise constant. nodes: one value per node, enforces a continuous model, using mean at values on discontinuities. The Salvus solver currently only supports 'element_nodes'.

    • Parameter type: string

    • Required: True

    • Default: "element_nodes"

    • Possible values: "element_nodes", "elements", "nodes"

  • model_spline_order

    • Pretty name: Model Spline Order

    • Description: Spline order used for model interpolation in case of layered models. Ignored for polynomial models like PREM.

    • Parameter type: integer

    • Required: True

    • Default: 3

  • compression

    • Pretty name: Compress Mesh

    • Description: If true, the final mesh will be compressed with gzip compression level 2. Compression is most effective for constant values and the compression level does matter much in that case. Slows down the mesh IO.

    • Parameter type: boolean

    • Required: True

    • Default: true

Attenuation Arguments group [attenuation]

Parameters for the memory variable approximation of attenuation. A detailed description can be found in van Driel et al. 2014b.

Required: True

Detailed description of all parameters:

  • number_of_linear_solids

    • Pretty name: Number of Linear Solids

    • Description: The number of standard linear solids used. 5 is conservative, in many applications 3 may be sufficient.

    • Parameter type: integer

    • Required: True

    • Default: 5

  • frequencies

    • Pretty name: Frequencies

    • Description: Minimum and maximum frequencies in the attenuation band. If either is not set, it will be determined automatically. Will be overwritten by 'auto_band'.

    • Parameter type: array of numbers

    • Required: False

    • Default: [0.001, 1.0]

  • power_law_reference_frequency

    • Pretty name: Power Law Reference Frequency

    • Description: Reference frequency for power law Q = Q_0 (f / f_0)^alpha, where Q_0 is taken from background model [Hz]. Also see Fichtner & van Driel 2014.*

    • Parameter type: number

    • Required: True

    • Default: 1.0

  • power_law_alpha

    • Pretty name: Power Law Alpha

    • Description: Exponent alpha for power law Q = Q_0 (f / f_0)^alpha. Also see Fichtner & van Driel 2014.*

    • Parameter type: number

    • Required: True

    • Default: 0.0

  • auto_band

    • Pretty name: Auto frequency bands

    • Description: Automatically determine attenuation band [f_min, f_max] using an empirical relation for the bandwidth and the resolved frequency of the mesh (provided in basic). Will overwrite any given frequencies.

    • Parameter type: boolean

    • Required: True

    • Default: true

Spherical Arguments group [spherical]

Parameters for spherical meshes.

Required: True

Detailed description of all parameters:

  • min_radius

    • Pretty name: Mimumum Radius

    • Description: Minimum radius in km.

    • Parameter type: number

    • Required: True

    • Default: 0.0

  • ellipticity

    • Pretty name: Ellipticity

    • Description: Ellipticity of the planet (WGS84: 0.0033528106647474805, GRS80: 0.003352810681182319, MARS: 0.00589). If nonzero, the mesh will be deformed according to the Clairaut equation to match the given ellipticity at the surface.

    • Parameter type: number

    • Required: True

    • Default: 0.0

  • gravity

    • Pretty name: Gravity

    • Description: Add gravitational acceleration from the 1D model as a field to the mesh. Solves the Poisson equation in the 1D model.

    • Parameter type: boolean

    • Required: True

    • Default: false

Refinement Arguments group [refinement]

Parameters for refinement of the meshes.

Required: True

Detailed description of all parameters:

  • refinement_style

    • Pretty name: Refinement Style

    • Description: The mesh refinement style. 'doubling' produces the highest quality elements, but requires twice the number of layers to refine compared to 'doubling_single_layer'. 'tripling' is best for models with strong velocity constrasts.

    • Parameter type: string

    • Required: True

    • Default: "doubling"

    • Possible values: "doubling", "tripling", "doubling_single_layer"

  • hmax_refinement

    • Pretty name: h_max Refinement

    • Description: Criterion (vertical oversamping factor BEFORE the refinement) for moving refinement layers downwards to avoid small timesteps caused by placing a refinement into a thin layer. Smaller values = more aggressive, needs to be > 1. For coarse meshes, larger values may be required. Ignored for 'local' refinement styles, if available.

    • Parameter type: number

    • Required: True

    • Default: 1.5

  • refinement_bottom_up

    • Pretty name: Refinement Bottom Up

    • Description: There are two approaches of locating refinements in the mesh: top down approach means minimizing number of elements at the surface at the cost of more elements at the bottom (default). If the option refinement_bottom_up is set, the bottom up approach is used instead, that is minimizing number of elements at the bottom at the cost of more elements at the surface. Which one is more efficient depends on the velocity model and refinement style. Ignored for 'local' refinement styles, if available.

    • Parameter type: boolean

    • Required: True

    • Default: false

  • horizontal_max_slowness_layer_index

    • Pretty name: Horizontal maximum slowness layer index (EXPERIMENTAL)

    • Description: For low velocity layers at the surface, horizontal refinements can be avoided if the source is below the LVL and hence cannot excite waves above a certain slowness. This is a 1D argument and might not me valid in 3D, hence check carefully. Ignored for 'local' refinement styles, if available.

    • Parameter type: integer

    • Required: True

    • Default: 0

3D Chunk Arguments group [chunk]

Parameters for single cubed sphere chunk 3D meshes.

Required: True

Detailed description of all parameters:

  • max_colatitude1

    • Pretty name: Maximum Colatitude

    • Description: Maximum colatitude of the mesh from the center.

    • Parameter type: number

    • Required: True

    • Default: 45.0

  • max_colatitude2

    • Pretty name: Maximum Colatitude

    • Description: Maximum colatitude of the mesh from the center.

    • Parameter type: number

    • Required: True

    • Default: 45.0

  • euler_angles

    • Pretty name: Euler Angles

    • Description: Euler angles to rotate a spherical chunk. E.g. to rotate to a center given by longitude and geocentric latitude use [latitude, longitude, 0]. The last angle then determines the azimuth.

    • Parameter type: array of null or number

    • Required: True

    • Default: [None, None, None]

Topography Arguments group [topography]

Adding topography to the mesh.

Required: True

Detailed description of all parameters:

  • topography_file

  • topography_varname

    • Pretty name: Topography Variable Name

    • Description: Variablename inside the topography file

    • Parameter type: string

    • Required: True

    • Default: ""

  • moho_topography_file

    • Pretty name: Moho Topography Filename

    • Description: Filename for moho topography, generated with salvus_topo: 'https://gitlab.com/Salvus/salvus_topo'

    • Parameter type: string

    • Required: True

    • Default: ""

  • moho_topography_varname

    • Pretty name: Moho Topography Variable Name

    • Description: Variablename inside the moho topography file

    • Parameter type: string

    • Required: True

    • Default: ""

  • anisotropic_refinement_style

    • Pretty name: Refinement Style for Anisotropic Refinement

    • Description: Use anisotropic refinement to adapt the number of elements in vertical direction to the crustal thickness. Assumes to have a single crustal layer. 'doubling' should be the preferred method, but is not compatible with a true ocean layer or a gravity mesh.

    • Parameter type: string

    • Required: True

    • Default: "none"

    • Possible values: "none", "doubling", "tripling"

Ocean Arguments group [ocean]

Adding a fluid ocean layer to the mesh.

Required: True

Detailed description of all parameters:

  • bathymetry_file

  • bathymetry_varname

    • Pretty name: Bathymetry Variable name

    • Description: Variablename inside the bathymetry file

    • Parameter type: string

    • Required: True

    • Default: ""

  • ocean_layer_vp

    • Pretty name: Ocean Layer vp

    • Description: P-wave velocity in the ocean in m/s.

    • Parameter type: number

    • Required: True

    • Default: 1450.0

  • ocean_layer_density

    • Pretty name: Ocean Layer Density

    • Description: Density in the ocean in kg/m**3.

    • Parameter type: number

    • Required: True

    • Default: 1020.0

  • ocean_layer_cutoff

    • Pretty name: Ocean Layer Cutoff

    • Description: Minimum bathymetry in km to be treated as fluid elements, smaller elements will be masked out and ocean loading approximation is used.

    • Parameter type: number

    • Required: True

    • Default: 1.0

  • shore_smoothing_factor

    • Pretty name: Shore smoothing factor

    • Description: Fraction of the element size to move the shore edge towards the water. For complicated shore lines smaller values might work better.

    • Parameter type: number

    • Required: True

    • Default: 0.3

  • ocean_layer_style

    • Pretty name: Ocean Layer Meshing Style

    • Description: How to add the ocean layer. 'loading' only adds the bathymetry as a variable to be used for ocean loading, 'extrude' adds a single layer, 'anisotropic_' adds a locally varying number of elements. The latter is not compatible with anisotropic_refinement_style 'doubling' in the crust'. Only 'anisotropic_tripling' is compatible with a mesh in the external domain.*

    • Parameter type: string

    • Required: True

    • Default: "none"

    • Possible values: "none", "loading", "extrude", "anisotropic_doubling", "anisotropic_tripling"

  • refine_at_ocean_bottom

    • Pretty name: Refine at Ocean Bottom (EXPERIMENTAL)

    • Description: Add refinement (tripling) at the ocean bottom. This should generally not be needed for sources in the crust due to total reflection of seismic waves at the ocean bottom. Mainly needed to verify this assumption.

    • Parameter type: boolean

    • Required: True

    • Default: false

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