PSD data

Particle size distribution (PSD) data consists of a range of particle densities given w.r.t to a corresponding grid of particle sizes. This module prvodies functionality for the handling of such PSD data.

Class reference

class parts.scattering.psd.data.psd_data.Area(a, b)

Bases: parts.scattering.psd.data.psd_data.SizeParameter

class parts.scattering.psd.data.psd_data.D_eq(rho)

Bases: parts.scattering.psd.data.psd_data.SizeParameter

class parts.scattering.psd.data.psd_data.D_max(a, b)

Bases: parts.scattering.psd.data.psd_data.SizeParameter

class parts.scattering.psd.data.psd_data.Mass

Bases: parts.scattering.psd.data.psd_data.SizeParameter

class parts.scattering.psd.data.psd_data.PSDData(x, data, size_parameter)

Bases: object

The PSDData class handles PSD data given as a discrete distribution over a given size grid.

The PSD data is stored as a numpy.ndarray of which the last dimension is assumed to correspond to the size parameter.

Attributes:

data(numpy.array): The discrete PSD data.

x(numpy.array): The size grid corresponding to the last dimension in data

size_parameter(SizeParameter): The size parameter used to represent the PSD.

change_size_parameter(size_parameter)

Change the size parameter of the data.

Parameters:

size_parameter(SizeParameter): The size parameter to convert the

data to.

rho(np.float): Particle density.

get_mass_density()

Computes the particle mass density corresponding to the PSD data.

Returns:

Array containing the particle mass density for each of the bulk volumes described by the PSD data

get_moment(p, reference_size_parameter=None)

Compute the $p$ th moment :math:M(p) of the PSD data:

$$M(p) = \int_0^\infty X^P$$

rac{dN}{dX}(X):dX

The physical significance of a moment of a PSD depends on the size parameter. So in general, the moments of the same PSD given w.r.t. different size parameters differ. If :code: reference_size_parameter argument is given then the computed moment will correspond to the Moment of the PSD w.r.t. to the given size parameter.

Parameters:

p(numpy.float): The moment which to compute.

reference_size_parameter(:class: SizeParameter): Size parameter with respect to which the moment should be computed.

Return:

The $p$ th moment of the particle size distribution.

get_number_density()

Computes the total particle number density ($0$ th moment).

Returns:

The particle number density for each volume element.

class parts.scattering.psd.data.psd_data.SizeParameter(a, b)

Bases: object

General representation of a size parameter of a PSD. The size parameter is represented by its mass-size relation, which gives the mass $m$ as a function of the size parameter $X$:

$$m(X) = a \cdot X^b$$

Attributes:

a(numpy.float): The $a$ factor of the mass-size relation

b(numpy.float): The $b$ exponent of the mass-size-relation

convert(src, x, y)

Conversion of PSD data given over one size parameter to another.

Parameters:

src(SizeParameter): The size parameter in which the PSD data is given.

x(numpy.ndarray): The size grid over which the PSD data is given. Must be broadcastable into the shape of y.

y(numpy.ndarray): The PSD data with the last axis corresponding to the size grid x.

Returns:

(x, y): Tuple containing the transformed size grid x and PSD data y

get_mass_density(x, y)

Compute the mass of the PSD for given PSD data.

Parameters:

x(numpy.ndarray): The size grid over which the PSD data is given. Must be broadcastable into the shape of y.

y(numpy.ndarray): The PSD data with the last axis corresponding to the size grid x.