PAABSF

Bulk Data Entry Defines the properties of the fluid acoustic absorber element.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PAABSF PID TZREID TSIMID S A B K RHOC  

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PAABSF 4 3 4 1.0 0.5        

Definitions

Field Contents SI Unit Example
PID Property identification number.

(Integer > 0)

 
TZREID TABLEDi entry identification number that defines the resistance as a function of frequency. The real part of the impedance.

(Integer > 0 or Blank)

 
TZIMID TABLEDi entry identification number that defines the reactance as a function of frequency. The imaginary part of impedance.

(Integer > 0 or Blank)

 
S Impedance scale factor.

Default = 1.0 (Real)

 
A Area factor when 1 or 2 grid points are specified in the CAABSF entry.

Default = 1.0 (Real > 0.0)

 
B Equivalent damping coefficient.

Default = 0.0 (Real)

 
K Equivalent stiffness coefficient.

Default = 0.0 (Real)

 
RHOC Constant used in data recovery for calculating an absorption coefficient.
RHO
Media density
C
Speed of sound in the media

Default = 1.0; current unused (Real)

 

Comments

  1. PAABSF is referenced by a CAABSF entry only.
  2. If only one grid point is specified on the CAABSF entry, the impedance Z ( f ) = Z R + i Z i MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aacaWGAbWaaeWaaeaacaWGMbaacaGLOaGaayzkaaGaeyypa0JaamOw amaaBaaaleaacaWGsbaabeaakiabgUcaRiaadMgacaWGAbWaaSbaaS qaaiaadMgaaeqaaaaa@42E5@ is the total impedance at the point. If two grids are specified, then the impedance is the impedance per unit length. If three or four points are specified, then the impedance is the impedance per unit area. Z R ( f ) = T Z R E I D ( f ) + B MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aacaWGAbWaaSbaaSqaaiaadkfaaeqaaOWaaeWaaeaacaWGMbaacaGL OaGaayzkaaGaeyypa0JaamivaiaadQfacaWGsbGaamyraiaadMeaca WGebWaaeWaaeaacaWGMbaacaGLOaGaayzkaaGaey4kaSIaamOqaaaa @474A@ and Z i ( f ) = T Z I M I D ( f ) = K / ( ω ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aacaWGAbGaamyAamaabmaabaGaamOzaaGaayjkaiaawMcaaiabg2da 9iaadsfacaWGAbGaamysaiaad2eacaWGjbGaamiramaabmaabaGaam OzaaGaayjkaiaawMcaaiabg2da9iaadUeacaGGVaWaaeWaaeaacqaH jpWDaiaawIcacaGLPaaaaaa@4B60@ .
  3. The resistance represents a damper quantity B. The reactance represents a quantity of the type ( ω M K / ω ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aadaqadaqaaiabeM8a3jaad2eacqGHsislcaWGlbGaai4laiabeM8a 3bGaayjkaiaawMcaaaaa@413C@ . The impedance is defined as:
    (1)
    Z = p / u
    Where,
    p MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aacaWGWbaaaa@39CC@
    Pressure
    u MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aacaWGWbaaaa@39CC@
    Velocity
  4. The impedance scale factor S is used in computing element stiffness and damping terms as:(2)
    k = A S 2 π f Z i ( f ) S R 2 + Z i 2 ( of shape functions ) b = A S 2 π f Z R ( f ) Z R 2 + Z i 2 ( of shape functions )
  5. To create a non-reflecting boundary, set the values of the TABLEDi entry referenced by the TZREID field (Resistance-real part of Impedance) to be equal to ( ρ fluid) * (cfluid) for all frequencies. This will allow the acoustic wave to propagate normally through the boundary, without reflection. This condition is called the Sommerfeld boundary condition.
    Where,
    ρ fluid
    Density of the fluid
    cfluid
    Speed of sound in the fluid
  6. This card is represented as a property in HyperMesh.