/MAT/LAW37 (BIPHAS)

Block Format Keyword

/MAT/LAW37 - Hydrodynamic Bi-Material Liquid Gas Material

Description

Describes the hydrodynamic bi-material liquid gas material. It is not recommended to use this multi-material laws (LAW37) with RADIOSS single precision engine.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW37/mat_ID or /MAT/BIPHAS/mat_ID
mat_title
Blank format
		Cl
				P0

Field	Contents	SI Unit Example
mat_ID	Material identifier (Integer, maximum 10 digits)
mat_title	Material title (Character, maximum 100 characters)
	Liquid reference density (Real)
Cl	Liquid bulk modulus (Real)
	Initial mass fraction liquid proportion (Real) = 0: gas = 1: liquid
	Shear kinematic viscosity () (Real)
	Volumetric viscosity (kinematic) for liquid: (Real) Default = 0: Stokes Hypothesis ()
	Reference gas density (Real)
	Perfect gas constant (Real)
P0	Reference gas initial pressure (Real)
	Shear kinematic viscosity = (Real)
	Volumetric viscosity (kinematic) for gas: (Real) Default = 0: Stokes Hypothesis ()

#RADIOSS STARTER

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#- 1. MATERIALS:

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/MAT/LAW37/1

air (unit g_mm_ms)

# RHO_l0 C_l ALPHA_l NU_l NU_VOL_l

.001 2089 0 .001 0

# RHO_G0 GAMMA P0 NU_g NU_VOL_g

1.22E-6 1.4 .1 .00143

/ALE/MAT/1

# Modif. factor.

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#enddata

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

1.	For each cycle equilibrium is computed between liquid and gas:

Liquid EOS:

with

where, c is the sound speed.

Gas EOS:

Where, Eint is the internal energy, is the perfect gas constant, and V is the volume.

Stress Tension

Where,

is the stress tension

is the spherical stress tension

is the viscous stress tension

is the shear viscosity (kinematic)

is the dilatation viscosity (kinematic)

2.	= 0 or Cl = 0 is the case of boundaries elements. In this case, the 3rd line/3rd field (Reference gas initial pressure P0) becomes an ID function for scaling initial liquid density versus time.

3.	In Animation files:

/ANIM/BRIC/USER2 is the density of gas ()

/ANIM/BRIC/USER3 is the density of liquid ()

/ANIM/BRIC/VFRAC allows to output volumetric fractions for both liquid and gas.

Refer to the /TH option in the RADIOSS Starter Manual, or refer to the /ANIM/Eltyp/Restype option in the RADIOSS Engine Manual).

4.	If using Law 37 coupled with Law 6 for liquid phase (without gas phase), the compatibility of the liquid EOS is as follows:

•	for Law 37

•

for Law 6

with,

C0 = P0

C1 = Cl

C2 = C3 = C4 = C5 = E0 = 0

5.	If using Law 37 coupled with Law 6 for gas phase (without liquid phase), the compatibility of the gas EOS is as follows:

PgV = ( - 1)Eint for Law 37

for Law 6

with,

C0 = C1 = C2 = C3 = 0

Where, E is the internal energy per initial volume.

Then, .

6. Multi-material law 51 (/MAT/MULTIMAT) can emulate LAW37 with less diffusion.