/EBCS

Block Format Keyword Describes the elementary boundary condition sets.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/EBCS/type/ebcs_ID/unit_ID
ebcs_title

Type: GRADP0, PRES, VALVIN or VALVOUT

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
surf_ID                  
C                
fct_IDpr Fscalepr              
fct_IDrho Fscalerho              
fct_IDen Fscaleen              
lc r1 r2        
Type: VEL
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
surf_ID                  
C                
fct_IDvx Fscalevx              
fct_IDvy Fscalevy              
fct_IDvz Fscalevz              
fct_IDrho Fscalerho              
fct_IDen Fscaleen              
lc r1 r2        
Type: NORMV
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
surf_ID                  
C                
fct_IDvim Fscalevim              
fct_IDrho Fscalerho              
fct_IDen Fscaleen              
lc r1 r2        
Type: INIP, INIV
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
surf_ID                  
Rho C l c        

Definitions

Field Contents SI Unit Example
type Elementary boundary condition keyword.

(see EBCS Type for available keywords)

 
ebcs_ID Elementary boundary condition identifier.

(Integer, maximum 10 digits)

 
unit_ID Unit 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)

[ m s ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada Wcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@
fct_IDpr Function f p r ( t ) identifier for pressure.
= 0
P = F s c a l e p r
= n
P = F s c a l e p r f p r ( t )

(Integer)

 
Fscalepr Pressure scale factor.

Default = 0 (Real)

[ Pa ]
fct_IDrho Function f r h o ( t ) identifier for density.
= 0
ρ = F s c a l e r h o
= n
ρ = F s c a l e r h o f r h o ( t )

(Integer)

 
Fscalerho Density scale factor.

Default = 0 (Real)

[ kg m 3 ]
fct_IDen Function f e n ( t ) identifier for energy.
= 0
E = F s c a l e e n
= n
E = F s c a l e e n f e n ( t )

(Integer)

 
Fscaleen Energy scale factor.

Default = 0 (Real)

[ J ]
l c Characteristic length.

Default = 0 (Real)

[ m ]
r1 Linear resistance. 6

Default = 0 (Real)

[ kg m 2 s ]
r2 Quadratic resistance. 6

Default = 0 (Real)

[ kg m 3 ]
fct_IDvx Function f V X ( t ) identifier for X velocity.
= 0
V X = F s c a l e V X
= n
V X = F s c a l e V X f V X ( t )

(Integer)

 
Fscalevx X velocity scale factor.

Default = 0 (Real)

[ kg m 3 ]
fct_IDvy Function f V Y ( t ) identifier for Y velocity.
= 0
V Y = F s c a l e V Y
= n
V Y = F s c a l e V Y f V Y ( t )

(Integer)

 
Fscalevy Y velocity scale factor.

Default = 0 (Real)

[ m s ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada Wcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@
fct_IDvz Function f V Z ( t ) identifier for Z velocity.
= 0
V Z = F s c a l e V Z
= n
V Z = F s c a l e V Z f V Z ( t )

(Integer)

 
Fscalevz Z velocity scale factor.

Default = 0 (Real)

[ m s ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada Wcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@
fct_IDvim Function f v i m ( t ) identifier for imposed velocity.
= 0
V = F s c a l e v i m
= n
V = F s c a l e v i m f v i m ( t )

(Integer)

 
Fscalevim Imposed velocity.

Default = 0 (Real)

[ m s ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada Wcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@
Rho Initial density.

Default = 0 (Real)

[ kg m 3 ]

EBCS Type

Table 1. 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

Comments

  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 (BIPHAS)) 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 less tha four or equal to six are non-reflective frontiers (NRF), using:
    (1)
    P t = ρ c V n t + c ( P P ) l c

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

    Where, l c is the characteristic length, to compute cutoff frequency f c as:(2)
    f c = c 2 π . l c
  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.(3)
    P r e s = r 1 V n + r 2 V n | V n |

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