/EOS/STIFF-GAS

Block Format Keyword Describes the ideal gas equation of state for stiffed gas P ( μ , E ) = ( γ − 1 ) ( 1 + μ ) E − γ P * MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa WdbiaadcfadaqadaWdaeaapeGaeqiVd0MaaiilaiaadweaaiaawIca caGLPaaacqGH9aqpdaqadaWdaeaapeGaeq4SdCMaeyOeI0IaaGymaa GaayjkaiaawMcaamaabmaapaqaa8qacaaIXaGaey4kaSIaeqiVd0ga caGLOaGaayzkaaGaamyraiabgkHiTiabeo7aNjaadcfadaahaaWcbe qaaiaacQcaaaaaaa@4C31@ .

This equation of state was originally designed to model water for underwater explosions.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/EOS/STIFF-GAS/mat_ID/unit_ID
eos_title
γ P0 Psh P * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa WdbiaadcfadaahaaWcbeqaaiaacQcaaaaaaa@382F@ ρ 0

Definitions

Field Contents SI Unit Example
mat_ID Material identifier.

(Integer, maximum 10 digits)

  
unit_ID Unit Identifier.

(Integer, maximum 10 digits)

  
eos_title EOS title.

(Character, maximum 100 characters)

  
γ Heat capacity ratio γ = C p C v MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape Gaeq4SdCMaeyypa0ZaaSaaa8aabaWdbiaadoeapaWaaSbaaSqaa8qa caWGWbaapaqabaaakeaapeGaam4qa8aadaWgaaWcbaWdbiaadAhaa8 aabeaaaaaaaa@3D36@ .

(Real)

  
P0 Initial pressure.

(Real)

 [ Pa ]
Psh Pressure shift.

(Real)

 [ Pa ]
P * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa WdbiaadcfadaahaaWcbeqaaiaacQcaaaaaaa@382F@ EOS additional pressure term.

(Real)

 [ Pa ]
ρ 0 Reference density.

Default = material density (Real)

 [ k g m 3 ]

Example

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
                   g                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/LAW06/7/1
water
#              RHO_I        
               0.001          
#                 NU                PMIN
 
/EOS/STIFF-GAS/7/1
STIFF_GAS_WATER
#              GAMMA                  P0                 PSH              P_STAR                RHO0
                 6.1                0.10                   0              368.85  
/ALE/MAT/7
 
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata

Comments

  1. (1)
    P ( μ , E ) = ( γ − 1 ) ( 1 + μ ) E − γ P * MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa WdbiaadcfadaqadaWdaeaapeGaeqiVd0MaaiilaiaadweaaiaawIca caGLPaaacqGH9aqpdaqadaWdaeaapeGaeq4SdCMaeyOeI0IaaGymaa GaayjkaiaawMcaamaabmaapaqaa8qacaaIXaGaey4kaSIaeqiVd0ga caGLOaGaayzkaaGaamyraiabgkHiTiabeo7aNjaadcfadaahaaWcbe qaaiaacQcaaaaaaa@4C31@
    Where,
    E = E i n t V 0
    µ = ρ ρ 0 − 1
  2. The stiffened gas EOS introduces an additional pressure term ( P * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaaaaa@37A7@ ) with respect to the ideal gas equation of state. The EOS is stated in this form because the speed of sound in water is:(2)
    c s = γ ( P + P * ) ρ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4yamaaBa aaleaacaWGZbaabeaakiabg2da9maakaaabaWaaSaaaeaacqaHZoWz caGGOaGaamiuaiabgUcaRiaadcfadaahaaWcbeqaaiaacQcaaaGcca GGPaaabaGaeqyWdihaaaWcbeaaaaa@416E@

    This way, by considering P * ≫ P MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaakiablUMi=iaadcfaaaa@39E3@ , the speed of sound will not be affected by P MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaaaa@36CC@ fluctuations and c s ≈ γ P * ρ MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4yamaaBa aaleaacaWGZbaabeaakiabgIKi7oaakaaabaWaaSaaaeaacqaHZoWz caWGqbWaaWbaaSqabeaacaGGQaaaaaGcbaGaeqyWdihaaaWcbeaaaa a@3F0A@ .

  3. P * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaaaaa@37A7@ can be calculated with:(3)
    P * = ρ c s 2 γ − P MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaakiabg2da9maalaaabaGaeqyWdiNaam4yamaa DaaaleaacaWGZbaabaGaaGOmaaaaaOqaaiabeo7aNbaacqGHsislca WGqbaaaa@40C2@

    As P * ≫ P MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaakiablUMi=iaadcfaaaa@39E3@ , P * ≈ ρ c s 2 γ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaakiabgIKi7oaalaaabaGaeqyWdiNaam4yamaa DaaaleaacaWGZbaabaGaaGOmaaaaaOqaaiabeo7aNbaaaaa@3FAB@ leads to a good estimate of P * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaaaaa@37A7@ .

  4. The stiffened gas EOS 1 can be derived from a polynomial EOS:(4)
    P = C 0 + C 1 μ + C 2 μ 2 + C 3 μ 3 + ( C 4 + C 5 μ ) E 0 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaiabg2 da9iaadoeadaWgaaWcbaGaaGimaaqabaGccqGHRaWkcaWGdbWaaSba aSqaaiaaigdaaeqaaOGaeqiVd0Maey4kaSIaam4qamaaBaaaleaaca aIYaaabeaakiabeY7aTnaaCaaaleqabaGaaGOmaaaakiabgUcaRiaa doeadaWgaaWcbaGaaG4maaqabaGccqaH8oqBdaahaaWcbeqaaiaaio daaaGccqGHRaWkdaqadaqaaiaadoeadaWgaaWcbaGaaGinaaqabaGc cqGHRaWkcaWGdbWaaSbaaSqaaiaaiwdaaeqaaOGaeqiVd0gacaGLOa GaayzkaaGaamyramaaBaaaleaacaaIWaaabeaaaaa@5292@
    Where,
    C 0 = − γ P * MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaaIWaaabeaakiabg2da9iabgkHiTiabeo7aNjaadcfadaah aaWcbeqaaiaacQcaaaaaaa@3CF9@
    C 1 = C 2 = C 3 = 0 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaaIXaaabeaakiabg2da9iaadoeadaWgaaWcbaGaaGOmaaqa baGccqGH9aqpcaWGdbWaaSbaaSqaaiaaiodaaeqaaOGaeyypa0JaaG imaaaa@3EF1@
    C 4 = C 5 = γ − 1 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa aaleaacaaI0aaabeaakiabg2da9iaadoeadaWgaaWcbaGaaGynaaqa baGccqGH9aqpcqaHZoWzcqGHsislcaaIXaaaaa@3ECB@
    E 0 = P 0 − C 0 C 4 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyramaaBa aaleaacaaIWaaabeaakiabg2da9maalaaabaGaamiuamaaBaaaleaa caaIWaaabeaakiabgkHiTiaadoeadaWgaaWcbaGaaGimaaqabaaake aacaWGdbWaaSbaaSqaaiaaisdaaeqaaaaaaaa@3EE3@
  5. For example, for water, ρ = 0.001 g . m m − 3 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyWdiNaey ypa0JaaGimaiaac6cacaaIWaGaaGimaiaaigdacaWGNbGaaiOlaiaa d2gacaWGTbWaaWbaaSqabeaacqGHsislcaaIZaaaaaaa@41B1@ , c s = 1500 m m . m s − 1 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4yamaaBa aaleaacaWGZbaabeaakiabg2da9iaaigdacaaI1aGaaGimaiaaicda caWGTbGaamyBaiaac6cacaWGTbGaam4CamaaCaaaleqabaGaeyOeI0 IaaGymaaaaaaa@4255@ and γ = 6.1 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4SdCMaey ypa0JaaGOnaiaac6cacaaIXaaaaa@3AD1@ can be found in literature. 1 This leads to P * = 368.852 M P a MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaCa aaleqabaGaaiOkaaaakiabg2da9iaaiodacaaI2aGaaGioaiaac6ca caaI4aGaaGynaiaaikdacaWGnbGaamiuaiaadggaaaa@4072@ . Thus, the stiffened gas EOS will give the following behavior at atmospheric pressure:


    Figure 1.
  6. Equations of state are used by Radioss to compute the hydrodynamic pressure and are compatible with the material laws:
    • /MAT/LAW3 (HYDPLA)
    • /MAT/LAW4 (HYD_JCOOK)
    • /MAT/LAW6 (HYDRO or HYD_VISC)
    • /MAT/LAW10 (DPRAG1)
    • /MAT/LAW12 (3D_COMP)
    • /MAT/LAW49 (STEINB)
    • /MAT/LAW102 (DPRAG2)
    • /MAT/LAW103 (HENSEL-SPITTEL)
1 Cole, R. H.; "Underwater Explosions. Princeton University Press" Princeton, New Jersey (1948)