Descriptionπ
The proudmanAcousticPower
function object
computes the acoustic power due to the volume of isotropic turbulence
using Proudmanβs formula.
The acoustic power, i.e. \(P_A\) [W/m^3] in terms of turbulent kinetic energy, i.e. \(k\), and turbulent kinetic energy dissipation rate, i.e. \(\epsilon\) is given as:
\[P_A = \alpha_\epsilon \rho \epsilon M_t^5\]where \(\alpha_\epsilon = 0.1\) is a constant and
\[M_t = \frac{\sqrt{2 k}}{a_0}\]with \(a_0\) the speed of sound.
The acoustic power is also output in dB
using:
where \(P_{\ref} = 1e^{-12}\) [W/m^3] is a constant.
Operandsπ
Operand | Type | Location |
---|---|---|
input | volScalarField |
$FOAM_CASE/<time>/<inpField> |
output file | - | - |
output field | volScalarField |
$FOAM_CASE/<time>/<outField> |
Usageπ
Example of the proudmanAcousticPower
function object
by using functions
sub-dictionary in system/controlDict
file:
proudmanAcousticPower1
{
// Mandatory entries (unmodifiable)
type proudmanAcousticPower;
libs (fieldFunctionObjects);
// Optional entries (runtime modifiable)
alphaEps 0.1;
// For incompressible flow simulations
rhoInf 1.225;
aRef 340;
// Optional (inherited) entries
region region0;
enabled true;
log true;
timeStart 0;
timeEnd 1000;
executeControl timeStep;
executeInterval 1;
writeControl timeStep;
writeInterval 1;
}
where the entries mean:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type | Type name: proudmanAcousticPower | word | yes | - |
libs | Library name: fieldFunctionObjects | word | yes | - |
rhoInf | Freestream density (for incompressible) | scalar | conditional | - |
aRef | Speed of sound (incompressible) | scalar | conditional | - |
alphaEps | Empirical model coefficient | scalar | no | 0.1 |
The inherited entries are elaborated in:
Usage by the postProcess
utility is not available.
Notes on entriesπ
The freestream density and reference speed of sound are only necessary when a thermodynamics package is unavailable, typically for incompressible cases.
Further informationπ
Tutorial:
Source code:
API:
History:
- Introduced in version v1912