pyva.properties.materialClasses.DelanyBazley

class pyva.properties.materialClasses.DelanyBazley(flow_res, c0=343.0, rho0=1.23, eta=0.0, dynamic_viscosity=1.84e-05, kappa=1.4, Cp=1005.1, heat_conductivity=0.0257673, miki=False)

Bases: Fluid

This class implements the empirical model of DelanyBazly or the revised Miki expressions

This class is a doughter class of fluid.

flow_res

Type:

flow resistivity

miki

Type:

Switch for use Delaney Bazley or Miki model. True means Miki model

__init__(flow_res, c0=343.0, rho0=1.23, eta=0.0, dynamic_viscosity=1.84e-05, kappa=1.4, Cp=1005.1, heat_conductivity=0.0257673, miki=False)

Construcutor of DelanyBazely class

The Delany Bazely model is an empirical model for fibre material, further refined and modified by Miki.

Parameters:

• flow_res (float) – flow resistivity

• miki (bool, optional) – Switch for use of Miki model. The default is False.

• c0 (complex, optional) – Speed of sound. The default is 343..

• rho0 (complex, optional) – density. The default is 1.23.

• eta (float, optional) – Damping loss. The default is 0.01.

• dynamic_viscosity (float, optional) – Dynamic viscosity. The default is 1.84e-5.

• kappa (float, optional) – ratio of specific heat capacities. The default is 1.4.

• Pr (float, optional) – Prandtl number. The default is 0.71.

Return type:

None.

Methods

__init__(flow_res[, c0, rho0, eta, ...])	Construcutor of DelanyBazely class
absorption(omega, impedance[, theta])	Absorption coefficient for interface to other fluids
absorption_diffuse(omega, z[, theta_max, ...])	Diffuse absorption coefficient for interface to other fluids
acoustic_FE(omega, S[, ID])	Acoustic Finite Element radiator/end condition of plane wave fluid
air(temperature, pressure[, h_rel])	Determine precise properties of air from ambient conditions.
c_freq([omega])	Complex, frequency dependent speed of sound
damping(omega)	Damping loss
impedance(omega)	Complex characteristic impedance including damping
infinite_layer_TM(omega, wavenumber, thickness)	Calculated transfermatrix of infinite fluid layer
reflection_factor(omega, impedance[, theta, ...])	Refection factor for interface to other fluids
rho_freq(omega)	frequency dependend density of fluid
shear_wavenumber(omega)	Shear wavenumber according to Maa's theory
wavelength(omega)	param omega: DESCRIPTION.
wavenumber(omega)	Wavenumber including damping

Attributes

Pr	Prandtl number.
diffusivity	Diffusivity.
frequency_limits	Frequency limits of Delany validity range.
kinematic_viscosity	Kinematic viscosity.
nu0	Kinematic viscosity.
z0	Real characteristic impedance without damping

property Pr

Prandtl number.

Returns:

Prandtl number.

Return type:

float

absorption(omega, impedance, theta=0)

Absorption coefficient for interface to other fluids

Parameters:

• omega (float) – angular frequency.

• impedance (complex) – impedance of interfacing fluid.

• theta (float, optional) – angle of incidence. The default is 0.

Returns:

Absorption coefficient.

Return type:

complex

absorption_diffuse(omega, z, theta_max=1.5550883635269477, theta_step=0.015707963267948967)

Diffuse absorption coefficient for interface to other fluids

Parameters:

• omega (float) – angular frequency.

• z (complex) – impedance.

• theta_max (float, optional) – Maximum integration angle. The default is np.pi/2*0.99.

• theta_step (float, optional) – Angle integration step. The default is np.pi/200.

Returns:

alpha – diffuse field absorption coefficient.

Return type:

float

acoustic_FE(omega, S, ID=[1], **kwargs)

Acoustic Finite Element radiator/end condition of plane wave fluid

See also

piston

Parameters:

• omega (float) – angular frequency.

• S (float) – tube cross section

• ID (list of int, optional) – list of input ID. The default is [1].

• **kwargs (TYPE) – DESCRIPTION.

Raises:

ValueError – DESCRIPTION.

Returns:

0D aoustic radiation mobility S/Z * p = Q Za = p/Q = p/(v*S) = Z/S

Return type:

DynamicMatrix

static air(temperature, pressure, h_rel=0.0)

Determine precise properties of air from ambient conditions.

Implementation is based on [1] that collects numerous papers dealing with various properties of air. Rasmussen condenses all papers into one formula collection.

[1] Rasmussen, K. (1997). Calculation methods for the physical properties of air used in the calibration of microphones.

Parameters:

• temperature (float) – temperature in Kelvin

• pressure (float) – atmospheric pressure in bar

• h_rel (float) – relative humidity in percent. The default is 0 (dry air).

Returns:

air with properties according to environmental conditions.

Return type:

Fluid

c_freq(omega=0.0)

Complex, frequency dependent speed of sound

Parameters:

omega (float) – Angular frequency.

Returns:

speed of sound.

Return type:

complex

damping(omega)

Damping loss

Parameters:

omega (float or ndarray) – DESCRIPTION.

Returns:

damping loss.

Return type:

float or ndarray

property diffusivity

Diffusivity.

Returns:

Diffusivity.

Return type:

float

property frequency_limits

Frequency limits of Delany validity range.

Returns:

• f_min (float) – minimum allowed frequency.

• f_max (float) – maximum allowed frequency.

impedance(omega)

Complex characteristic impedance including damping

Parameters:

omega (float or ndarray) – angular frequency.

Returns:

characteristic impedance.

Return type:

complex

infinite_layer_TM(omega, wavenumber, thickness, ID=[1, 2], **kwargs)

Calculated transfermatrix of infinite fluid layer

Deprecated: This method is part of the FluidLayer class

Parameters:

• omega (float) – angular frequency.

• wavenumber (float) – wavenumbner in plane direction.

• thickness (float) – thickness of fluid layer.

• ID (list if int, optional) – list of input and output ID. The default is [1,2].

• **kwargs (TYPE) – DESCRIPTION.

Raises:

ValueError – DESCRIPTION.

Returns:

transfer matrix of infinite fluid layer.

Return type:

DynamicMatrix

property kinematic_viscosity

Kinematic viscosity.

Returns:

Kinematic viscosity.

Return type:

float

property nu0

Kinematic viscosity.

Returns:

Kinematic viscosity

Return type:

float

reflection_factor(omega, impedance, theta=0, area=1.0)

Refection factor for interface to other fluids

Parameters:

• omega (float) – angular frequency.

• impedance (complex) – impedance of interfacing fluid.

• theta (float, optional) – angle of incidence. The default is 0.

• area (float, optional) – ?????? . The default is 1..

Returns:

reflection coefficient.

Return type:

complex

rho_freq(omega)

frequency dependend density of fluid

Parameters:

omega (float) – Angular frequency.

Returns:

density

Return type:

complex

shear_wavenumber(omega)

Shear wavenumber according to Maa’s theory

Parameters:

omega (float or ndarray) – angular frequency.

Returns:

wavenumber

Return type:

complex

wavelength(omega)

Parameters:

omega (TYPE) – DESCRIPTION.

Returns:

wavelength

Return type:

float

wavenumber(omega)

Wavenumber including damping

Parameters:

omega (TYPE) – DESCRIPTION.

Returns:

Complex wavenumber

Return type:

complex

property z0

Real characteristic impedance without damping

Returns:

Characteristic impedance.

Return type:

float