The proudmanAcousticPower
function object computes the acoustic power due to the volume of isotropic turbulence using Proudman's 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:
\[ L_P = 10 \log \frac{P_A}{P_{ref}} \]
where \(P_{ref} = 1e^{-12}\) [W/m^3] is a constant.
Operand | Type | Location |
---|---|---|
input | volScalarField | $FOAM_CASE/<time>/<inpField> |
output file | - | - |
output field | volScalarField | $FOAM_CASE/<time>/<outField> |
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.
The freestream density and reference speed of sound are only necessary when a thermodynamics package is unavailable, typically for incompressible cases.
Tutorial:
Source code:
History