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Calculates the acoustic power due to the volume of isotropic turbulence
using Proudman's formula
The acoustic power \f$ P_A \f$ [W/m3] in terms of turbulence \f$ k \f$
and \f$ \epsilon \f$ is given as:
\f[
P_A = alpha_\epsilon \rho \epsilon M_t^5
\f]
where \f$ alpha_\epsilon \f$ is a constant (0.1) and
\f[
M_t = \frac{\sqrt{2 k}}{a_0}
\f]
with \f$ a_0 \f$ the speed of sound. The acoustic power is also output in
dB using:
\f[
L_P = 10 \log \frac{P_A}{P_ref}
\f]
where \f$ P_ref \f$ is a constant (1e-12 W/m3)
Usage
Example of function object specification to calculate the Proudman acoustic
power
proudmanAcousticPower1
{
type proudmanAcousticPower;
libs ("libfieldFunctionObjects.so");
...
// Required additional entries for incompressible calculations
rhoInf 1.225;
aRef 340;
}
Where the entries comprise:
Property | Description | Required | Default value
type | type name: proudmanAcousticPower | yes |
rhoInf | Freestream density for incompressible cases | no |
aRef | Reference spped of sound for incompressible cases | no |
alphaEps | Model coefficient | no | 0.1
Note
- The freestream density and reference speed of sound are only necessary
when a thermodynamics package is unavailable, typically for incompressible
cases.