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/MAT/LAW51 - Iform=5: Inlet Boundaries for Multi-Material ALE Law

Description

This boundary enables to handle gas inlet conditions for multi-material ALE laws (formulation: Iform = 0, 1, 10, or 11). Boundary sub-material states are computed using provided state at a stagnation point and polynomial EOS. This avoids defining an imposed velocity (/IMPVEL).

Bernoulli theory is applied:

Liquid is modeled using linear EOS.

law51_iform4

Format

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/MAT/LAW51/mat_ID

mat_title

Blank Format

Iform

 

 

 

 

 

 

 

 

 

 

#Global Parameters

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Scaletime

PEXT

 

 

 

 

 

 

#Material1 Parameters

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E0mat_1

fct_IDsymbol_a_141

fct_IDdensity1

fct_IDE1

 

C1mat_1

 

 

 

 

C0mat_1

 

 

 

 

 

 

#Material2 Parameters

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E0mat_2

fct_IDsymbol_a_142

fct_IDdensity2

fct_IDE2

 

C1mat_2

 

 

 

 

C0mat_2

 

 

 

 

 

 

#Material3 Parameters

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E0mat_3

fct_IDsymbol_a_143

fct_IDdensity3

fct_IDE3

 

C1mat_3

 

 

 

 

C0mat_3

 

 

 

 

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

mat_ID

Material identifier

(Integer, maximum 10 digits)

 

mat_title

Material title

(Character, maximum 100 characters)

 

Iform

Formulation flag

(Integer)

= 5: Liquid Inlet (computed from data at stagnation point)

 

Scaletime

Abscissa scale factor for input functions (Comment 2)

Default = 1 (Real)

 

PEXT

External (ambient) pressure (Comment 3)

(Real)

symbol_Pa

Initial volumetric fraction (Comment 4)

(Real)

 

Initial density at stagnation point (Comment 1)

(Real)

symbol_kg

E0mat_i

Initial density energy at stagnation point (Comment 5)

(Real)

fail_energy

fct_IDsymbol_a_14i

(Optional) Volumetric fraction scaling function identifier (Comment 6)

= 0:

> 0:

(Integer)

 

fct_IDdensityi

(Optional) Volumetric fraction scaling function identifier

= 0:

> 0:

(Integer)

 

fct_IDEi

(Optional) Volumetric fraction scaling function identifier

= 0:

> 0:

(Integer)

 

C1mat_i

Coefficient for perfect gas EOS (Comment 5)

(Real)

symbol_Pa

C4mat_i

Perfect gas (symbol_y - 1) constant (Comment 5)

(Real)

 

Hydrodynamic cavitation pressure (Comment 6)

Default = -10-30  (Real)

symbol_Pa

C0mat_i

Coefficient for perfect gas EOS (Comment 5)

(Real)

symbol_Pa
hmtoggle_plus1Comments
1.Provided gas state from stagnation point is used to compute inlet gas state. Bernoulli theorem is applied:

This leads to sub-material state in inlet boundary element:

Then global material state is determined by computing a mean value:

Pressure:

Density:

Energy:

2.Provided optional scale function can be used, such as f (Scaletime * t) is used, instead of f(t).
3.Parameter PEXT enables you to take into account ambient pressure in case you want to work with relative pressure . This parameter is required by RADIOSS for correct energy integration at each cycle. Otherwise, numerical EOS solving is generally incorrect. It represents pressure which must be added to EOS calculation to obtain total (physical) pressure. It has no influence on pressure contour in animation files.

Example using linear EOS:

Total pressure: , and also PEXT = 0

Relative Pressure: , and also PEXT = Pamb

4.Volumetric fractions enable the sharing of elementary volume within the three different materials.

For each material, must be defined between 0 and 1.

Sum of initial volumetric fractions must be equal to 1.

For automatic initial fraction of the volume, refer to /INIVOL.

5.Linear EOS is . This provides flexibility, depending on whether pressure and energy can be total or relative:

where and PEXT = 0.

This leads to usual form from .

where and PEXT = Pamb

6. flag is the minimum value for the computed pressure.

Since P = symbol_dp + PEXT, defining PEXT = 0 implies symbol_dp = P and symbol_dpmin = Pmin.

Fluid materials pressure must remain positive to avoid any tensile strength, then

Pmin = 0 leads to symbol_dpmin = -PEXT

For solid materials, the default value for = 1030 is suitable.

7.Stagnation Energy is optional, for this EOS does not depends on energy. Input value will only affect output value in animation files and time histories.
8.EOS parameters must be consistent with gas EOS from adjacent MM-ALE domain.