Iform = 0
Block Format Keyword The material law is based on a diffusive interface technique.
To get sharper interfaces between submaterial zones, refer to /ALE/MUSCL.
- P
- Positive for a compression and negative for traction.
Where, E=Eint/V0, C'2=C2δμ≥0 and C'3=C3δμ≥0 mean that the EOS is linear for an expansion and cubic for a compression.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/MAT/LAW51/mat_ID/unit_ID | |||||||||
mat_title | |||||||||
Blank | |||||||||
Iform |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
Pext | ν | νvol |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat _ 10 | ρmat _ 10 | Emat _ 10 | ΔPmat _1 min | Cmat _ 10 | |||||
Cmat _ 11 | Cmat _ 12 | Cmat _ 13 | Cmat _ 14 | Cmat _ 15 | |||||
Gmat _ 11 |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat _ 20 | ρmat _ 20 | Emat _ 20 | ΔPmat _2 min | Cmat _ 20 | |||||
Cmat _ 21 | Cmat _ 22 | Cmat _ 23 | Cmat _ 24 | Cmat _ 25 | |||||
Gmat _ 21 |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat _ 30 | ρmat _ 30 | Emat _ 30 | ΔPmat _3 min | Cmat _ 30 | |||||
Cmat _ 31 | Cmat _ 32 | Cmat _ 33 | Cmat _ 34 | Cmat _ 35 | |||||
Gmat _ 31 |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
mat_ID | Material
identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit Identifier. (Interger, maximum 10 digits) |
|
mat_title | Material
title. (Character, maximum 100 characters) |
|
Iform | Formulation
flag. (Integer) |
|
Pext | External pressure. 2 Default = 0 (Real) |
[Pa] |
ν | Kinematic viscosity shear
ν=μ/ρ
. 3 Default = 0 (Real) |
[m2s] |
νvol | Kinematic viscosity
(volumetric),
νvol=3λ+2μρ
which corresponds to Stokes
Hypothesis. 3 Default = 0 (Real) |
[m2s] |
αmat _ i0 | Initial volumetric
fraction. 4 (Real) |
|
ρmat _ i0 | Initial
density. (Real) |
[kgm2] |
Emat _ i0 | Initial energy per unit
volume. (Real) |
[Jm3] |
ΔPmat _imin | Hydrodynamic cavitation
pressure. 5 If fluid material ( Gmat _ i1=0 ), then default = −Pext . If solid material ( Gmat _ i1≠0 ), then default = -1e30. (Real) |
[Pa] |
Cmat _i0 | Initial
pressure. (Real) |
[Pa] |
Cmat _i1 | Hydrodynamic
coefficient. (Real) |
[Pa] |
Cmat _i2 | Hydrodynamic
coefficient. (Real) |
[Pa] |
Cmat _i3 | Hydrodynamic
coefficient. (Real) |
[Pa] |
Cmat _i4 | Hydrodynamic
coefficient. (Real) |
|
Cmat _i5 | Hydrodynamic
coefficient. (Real) |
|
Gmat _i1 | Elasticity shear modulus.
(Real) |
[Pa] |
Example
/MAT/LAW51/1
99.99% Water + 0.01% Air-MULTIMAT: AIR+WATER,units{kg,m,s,Pa}
#(output is total pressure:Pext=0)
#--------------------------------------------------------------------------------------------------#
# Material Law No 51. MULTI-MATERIAL SOLID LIQUID GAS ALE-CFD-SPH
#--------------------------------------------------------------------------------------------------#
# Blank format
# IFORM
0
#---Global parameters------------------------------------------------------------------------------#
# P_EXT NU LAMDA
0 0 0
#---Material#1:AIR(PerfectGas)---------------------------------------------------------------------#
# ALPHA_1 RHO_0_1 E_0_1 P_MIN_1 C_0_1
0.0001 1.2 2.5E+05 0 0
# C_1_1 C_2_1 C_3_1 C_4_1 C_5_1
0 0 0 0.4 0.4
# G_1
0
#---Material#2:WATER(Linear_Incompressible)--------------------------------------------------------#
# ALPHA_2 RHO_0_2 E_0_2 P_MIN_2 C_0_2
0.9999 1000.0 0 0 0
# C_1_2 C_2_2 C_3_2 C_4_2 C_5_2
2.25E+9 0 0 0 0
# G_2
0
#---Material#3:not defined-------------------------------------------------------------------------#
# ALPHA_3 RHO_0_3 E_0_3 P_MIN_3 C_0_3
0.0 0 0 0 0
# C_1_3 C_2_3 C_3_3 C_4_3 C_5_3
0 0 0 0 0
# G_3
0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/LAW51/1
99.99% Water + 0.01% Air-MULTIMAT: AIR+WATER,units{kg,m,s,Pa}
#(output is relative pressure to Pext=1E+5Pa)
#--------------------------------------------------------------------------------------------------#
# Material Law No 51. MULTI-MATERIAL SOLID LIQUID GAS -ALE-CFD-SPH
#--------------------------------------------------------------------------------------------------#
# Blank format
# IFORM
0
#---Global parameters------------------------------------------------------------------------------#
# P_EXT NU LAMDA
1E+5 0 0
#---Material#1:AIR(PerfectGas)---------------------------------------------------------------------#
# ALPHA_1 RHO_0_1 E_0_1 P_MIN_1 C_0_1
0.0001 1.2 2.5E+05 0 -1E+5
# C_1_1 C_2_1 C_3_1 C_4_1 C_5_1
0 0 0 0.4 0.4
# G_1
0
#---Material#2:WATER(Linear_Incompressible)--------------------------------------------------------#
# ALPHA_2 RHO_0_2 E_0_2 P_MIN_2 C_0_2
0.9999 1000.0 0 0 0
# C_1_2 C_2_2 C_3_2 C_4_2 C_5_2
2.25E+9 0 0 0 0
# G_2
0
#---Material#3:not defined-------------------------------------------------------------------------#
# ALPHA_3 RHO_0_3 E_0_3 P_MIN_3 C_0_3
0.0 0 0 0 0
# C_1_3 C_2_3 C_3_3 C_4_3 C_5_3
0 0 0 0 0
# G_3
0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
Comments
- Numerical diffusion can be improved using the second order method for volume fraction convection, /ALE/MUSCL. The previous /UPWIND used to limit diffusion is now obsolete
-
Radioss computes and outputs a relative pressure
ΔP
.
(6) ΔP=max {ΔPmin, C0+C1μ+C'2μ2+C'3μ3+(C4+C5μ)E(μ)}However, total pressure is essential for energy integration ( dEint=−PdV ). It can be computed with the external pressure flag Pext.
P=ΔP+Pext leads to dEint=−(Pext+ΔP)dV .
This means that if Pext = 0, the computed pressure ΔP is also the total pressure: ΔP=P
- Kinematic viscosities
are global and is not specific to each material. It allows computing viscous stress
tensor:
(7) τ=μ[(∇⊗V)+ t(∇⊗V)]+λ(∇V)IWhere,- ν=μ/ρ
- Kinematic viscosity in shear
- νvol=3(λ+2μ3)ρ
- Kinematic volumetric viscosity
- Volumetric fractions enable the sharing of elementary volume within the
three different materials.
For each material αmat _ i0 must be defined between 0 and 1.
Sum of initial volumetric fractions ∑3i=1αmat_i0 must be equal to 1.
For automatic initial fraction of the volume, refer to the /INIVOL card.
-
ΔPmat _imin
flag is the minimum value for the computed pressure
ΔP
. It means that total pressure is also bounded
to:
(8) Pmat _imin=ΔPmat_imin+PextFor fluid materials and detonation products, Pmat _imin must remain positive to avoid any tensile strength so ΔPmat _imin must be set to −Pext .
For solid materials, default value ΔPmat _imin = 1e-30 is suitable but may be modified.
- Material tracking is possible through animation
files:
/ANIM/BRIC/VFRAC (All material volumetric fractions)