pyva.properties.materialClasses.EquivalentFluid

class pyva.properties.materialClasses.EquivalentFluid(flow_res, porosity, tortuosity, rho_bulk, length_visc, length_therm, limp=True, c0=343.0, rho0=1.23, eta=0.0, dynamic_viscosity=1.84e-05, kappa=1.4, Cp=1005.1, heat_conductivity=0.0257673)

Bases: Fluid

The EquivalentFluid class deals with fibre models based on Champoux Allard with limp/rigid frame theory

This class is a doughter class of fluid.

flow_res

Type:: flow resistivity

porosity

Type:: volume porosity

tortuosity

Type:: tortuosity (alpha_inf)

rho_bulk

Type:: apearant density of fluid and matrix

length_visc

Type:: viscous characteristic length

length_therm

Type:: thermal characteristic length

limp

Type:: Switch for use of limp model, false means rigid frame

all original attributes of fluid

See [All2005]_ for details of the theory

__init__(flow_res, porosity, tortuosity, rho_bulk, length_visc, length_therm, limp=True, c0=343.0, rho0=1.23, eta=0.0, dynamic_viscosity=1.84e-05, kappa=1.4, Cp=1005.1, heat_conductivity=0.0257673)

Construcutor of equivalent fluid class

The equivalent fluid model deals with the propagation of sound waves through a geometrical porous construction. It models the acoustic motion inside the skeleon and the viscous and thermal interactions between fluid and skeleton.

Parameters:

flow_res (float) – flow resistivity
porosity (float) – volume porosity.
tortuosity (float) – tortuosity (alpha_inf)N.
rho_bulk (float) – apearant density of fluid and matrix.
length_visc (float) – viscous characteristic lengt.
length_therm (float) – thermal characteristic length.
limp (bool, optional) – Switch for use of limp model. The default is True.
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

`G`(omega)	Characteristic function of the equivalent fluid
`__init__`(flow_res, porosity, tortuosity, ...)	Construcutor of equivalent fluid 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.
`bulk_modulus`(omega)	Dynamic complex bulk modulus of the equivalent fluid
`c_freq`(omega)	Complex, frequency dependent speed of sound of the equivalent fluid
`damping`(omega)	Damping loss
`impedance`(omega)	Complex characteristic impedance of the equivalent fluid
`infinite_layer_TM`(omega, wavenumber, thickness)	Calculated transfermatrix of infinite fluid layer
`inverse_parameter_derivation`(flow_res, ...)	Create EquivalentFluid object from test paramters
`propagation_constant`(omega)	param omega: angular frequency
`reflection_factor`(omega, impedance[, theta, ...])	Refection factor for interface to other fluids
`rho_freq`(omega)	Complex density of the equivalent fluid
`rho_rigid`(omega)	Dynamic complex density of the equivalent fluid with rigid matrix
`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.
`kinematic_viscosity`	Kinematic viscosity.
`nu0`	Kinematic viscosity.
`z0`	Real characteristic impedance without damping

G(omega)

Characteristic function of the equivalent fluid

Parameters:: omega (float) – angular frequency.
Returns:: Characteristic function.
Return type:: complex

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

bulk_modulus(omega)

Dynamic complex bulk modulus of the equivalent fluid

Parameters:: omega (float) – angular frequency.
Returns:: Dynamic complex bulk modulus.
Return type:: complex

c_freq(omega)

Complex, frequency dependent speed of sound of the equivalent fluid

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

impedance(omega)

Complex characteristic impedance of the equivalent fluid

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

static inverse_parameter_derivation(flow_res, porosity, rho_bulk, fluid, rho_eq, K_eq, omega, limp=True)

Create EquivalentFluid object from test paramters

Parameters:

flow_res (float) – flow resistivity
porosity (float) – volume porosity.
rho_bulk (float) – apearant density of fluid and matrix.
fluid (Fluid) – fluid during test in the fluid phase of the absorber.
rho_eq (complex nd.array of size (N,) or complex) – Equivalent density of absorber material under test.
K_eq (complex nd.array of size (N,) or complex) – Equivalent bulk modulus of absorber material under test.
omega (ndarray of size (N,) or float) – Upper and lower limit for averaging
limp (bool, optional) – Switch for use of limp model. The default is True.

Returns:

LMS extimation of the materail due to test results.

Return type:

EquivalentFluid

property kinematic_viscosity

Kinematic viscosity.

Returns:: Kinematic viscosity.
Return type:: float

property nu0

Kinematic viscosity.

Returns:: Kinematic viscosity
Return type:: float

propagation_constant(omega)

Parameters:: omega (float or ndarray) – angular frequency
Returns:: propagation constant.
Return type:: complex

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)

Complex density of the equivalent fluid

Parameters:: omega (float) – angular frequency.
Returns:: Complex density.
Return type:: complex

rho_rigid(omega)

Dynamic complex density of the equivalent fluid with rigid matrix

Parameters:: omega (float) – angular frequency.
Returns:: Dynamic complex 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