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/EBCS - Elementary Boundary Conditions Sets (EBCS)

Description

Describes the elementary boundary condition sets.

Format
Type: GRADP0, PRES, VALVIN, VALVOUT

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/EBCS/type/ebcs_ID

ebcs_title

surf_ID

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

fct_IDpr

Fscalepr

 

 

 

 

 

 

 

fct_IDrho

Fscalerho

 

 

 

 

 

 

 

fct_IDen

Fscaleen

 

 

 

 

 

 

 

lc

r1

r2

 

 

 

 

 

Type: VEL

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surf_ID

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

fct_IDvx

Fscalevx

 

 

 

 

 

 

 

fct_IDvy

Fscalevy

 

 

 

 

 

 

 

fct_IDvz

Fscalevz

 

 

 

 

 

 

 

fct_IDpr

Fscalepr

 

 

 

 

 

 

 

fct_IDrho

Fscalerho

 

 

 

 

 

 

 

fct_IDen

Fscaleen

 

 

 

 

 

 

 

lc

r1

r2

 

 

 

 

 

Type: NORMV

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surf_ID

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

fct_IDvim

Fscalevim

 

 

 

 

 

 

 

fct_IDrho

Fscalerho

 

 

 

 

 

 

 

fct_IDen

Fscaleen

 

 

 

 

 

 

 

lc

r1

r2

 

 

 

 

 

Type: INIP, INIV

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surf_ID

 

 

 

 

 

 

 

 

 

Rho

C

lc

 

 

 

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

type

Elementary boundary condition keyword

(see table below for available keywords)

 

ebcs_ID

Elementary boundary condition identifier

(Integer, maximum 10 digits)

 

ebcs_title

Elementary boundary condition title

(Character, maximum 100 characters)

 

surf_ID

Surface identifier

(Integer)

 

C

Speed of sound

Default = 0  (Real)

fail_lad_SI_k

fct_IDpr

Function f (t) identifier for pressure

(Integer)

= 0: P = Fscalepr

= n: P = Fscalepr * f (t)

 

Fscalepr

Pressure scale factor

Default = 0  (Real)

symbol_Pa

fct_IDrho

Function f (t) identifier for density

(Integer)

= 0: density = Fscalerho

= n: density = Fscalerho * f (t)

 

Fscalerho

Density scale factor

Default = 0  (Real)

symbol_kg

fct_IDen

Function f (t) identifier for energy

(Integer)

= 0: E = Fscaleen

= n: E = Fscaleen * f (t)

 

Fscaleen

Energy scale factor

Default = 0  (Real)

symbol_J

lc

Characteristic length

Default = 0  (Real)

symbol_m

r1

Linear resistance (Comment 6)

Default = 0  (Real)

symbol_kg_m2s

r2

Quadratic resistance (Comment 6)

Default = 0  (Real)

symbol_kg

fct_IDvx

Function f (t) identifier for X velocity

(Integer)

= 0: VX = Fscalevx

= n: VX = Fscalevx * f (t)

 

Fscalevx

X velocity scale factor

Default = 0  (Real)

fail_lad_SI_k

fct_IDvy

Function f (t) identifier for Y velocity

(Integer)

= 0: Vy = Fscalevy

= n: Vy = Fscalevy * f (t)

 

Fscalevy

Y velocity scale factor

Default = 0  (Real)

fail_lad_SI_k

fct_IDvz

Function f (t) identifier for Z velocity

(Integer)

= 0: VZ = Fscalevz

= n: VZ = Fscalevz * f (t)

 

Fscalevz

Z velocity scale factor

Default = 0  (Real)

fail_lad_SI_k

fct_IDvim

Function f (t) identifier for imposed velocity

(Integer)

= 0: V = Fscalevim

= n: V = Fscalevim * f (t)

 

Fscalevim

Imposed velocity

Default = 0  (Real)

fail_lad_SI_k

Rho

Initial density

Default = 0  (Real)

symbol_kg
hmtoggle_plus1EBCS Type

The following table lists the element compatibilities with material:

Type

Keyword

Description

0

GRADP0

Zero pressure gradient. Is not allowed for SPMD parallel version.

1

PRES

Imposed density and pressure

2

VALVIN

Inlet valve (Imposed density and pressure)

3

VALVOUT

Outlet valve (Imposed density and pressure)

4

VEL

Imposed velocity

5

NORMV

Imposed normal velocity

6

INIP

Initial pressure

7

INIV

Initial velocity
hmtoggle_plus1Comments
1.Input is general, no prior assumptions are enforced!  You must verify that the elementary boundaries are consistent with general assumptions of ALE (equation closure).
2.It is not advised to use the Hydrodynamic Bi-material Liquid Gas Law (/MAT/LAW37) with the elementary boundary conditions.
3.Density, pressure, energy are imposed according to a scale factor and a time function. If the function number is 0, the imposed density, pressure and energy are used.
4.All EBCS which type is inferior to four or equal to six are non-reflective frontiers (NRF). The following equation is used:

Pressure in the far field Psymbol_inf is imposed with a function of time. The transient pressure is derived from Psymbol_inf, the local velocity field V and the normal of the outlet facet.

Where, lc is the characteristic length, to compute cutoff frequency f c as:

clip0613

5.In order to impose a positive velocity fct_IDvim (for instance 15 m/s), you must input -fct_IDvim (for instance -15 m/s).
6.A resistance pressure is computed and added to the current pressure.

Pres = r1 vn + r2 vn |vn|

It aims at modeling the friction loss due to the valves.