PARAM, SPLC

Bulk Data Entry Specifies the speed of sound used in the wave number and the complex particle velocity vector calculations.

Parameter	Values	Description
`SPLC`	< Real > 0.0 > Default = 1.0	This parameter is used to specify the speed of sound used in the wave number and the complex particle velocity vector calculations, as shown below (refer to Radiated Sound Output Analysis in the User Guide for further information): Wave Number The wave number $k$ is defined as: $k = \frac{2 π f}{c}$ Where, $c$ Speed of sound defined by PARAM, `SPLC` $f$ Frequency of the sound wave in the medium Complex Particle Velocity Vector The complex particle velocity vector is defined for each frequency as: ${\vec{(p v)}}_{j} (f) = \frac{p_{j} (f) {\hat{X}}_{j}}{ρ c} (1 - \frac{i}{k r_{j}})$ Where, p_j(f) Complex acoustic pressure due to source grid $j$ at the microphone location. ${\hat{X}}_{j}$ Unit vector from the source grid $j$ to the microphone grid. $({\hat{X}}_{j} = \frac{{\vec{X}}_{j}}{\| {\vec{X}}_{j} \|} = \frac{{\vec{X}}_{j}}{r_{j}})$ $ρ$ Density of the acoustic medium defined by PARAM, `SPLRHO`. $c$ Speed of sound defined by PARAM, `SPLC`. $k$ Wave number defined above under Wave Number. $r_{j}$ Distance from the acoustic source grid $j$ on the panel to the microphone grid. $i$ Square root of -1.

Parameter

Values

Description

SPLC

< Real > 0.0 >

Default = 1.0

This parameter is used to specify the speed of sound used in the wave number and the complex particle velocity vector calculations, as shown below (refer to Radiated Sound Output Analysis in the User Guide for further information):

Wave Number

The wave number $k$ is defined as:

k = \frac{2 π f}{c}

Where,

$c$: Speed of sound defined by PARAM, SPLC
$f$: Frequency of the sound wave in the medium

Complex Particle Velocity Vector

The complex particle velocity vector is defined for each frequency as:

{\vec{(p v)}}_{j} (f) = \frac{p_{j} (f) {\hat{X}}_{j}}{ρ c} (1 - \frac{i}{k r_{j}})

Where,

p_j(f): Complex acoustic pressure due to source grid $j$ at the microphone location.
${\hat{X}}_{j}$: Unit vector from the source grid $j$ to the microphone grid.

({\hat{X}}_{j} = \frac{{\vec{X}}_{j}}{| {\vec{X}}_{j} |} = \frac{{\vec{X}}_{j}}{r_{j}})

$ρ$: Density of the acoustic medium defined by PARAM, SPLRHO.
$c$: Speed of sound defined by PARAM, SPLC.
$k$: Wave number defined above under Wave Number.
$r_{j}$: Distance from the acoustic source grid $j$ on the panel to the microphone grid.
$i$: Square root of -1.

Comments

This parameter is used to specify the speed of sound used in Radiated Sound Analysis. The same value is used in the Equivalent Radiated Power (ERP) calculations (See PARAM, ERPC).
If both PARAM, SPLC and PARAM, ERPC are specified in the same input deck, then the last instance dominates.