/BEM/DAA

Block Format Keyword Doubly Asymptotic Approximation for Underwater Explosion, where the fluid mass matrix is computed by boundary element method.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/BEM/DAA/daa_ID/unit_ID
daa_title
surf_ID grav_ID            
ρ C Pmin        
Xs Ys Zs        
Iform Ipri Ipres     Kform Freesurf Afterflow Integr  
Insert if Ipres=1
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Pm θ a aθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGHbWaaSbaaSqaaiabeI7aXbqabaaaaa@3A30@    
Insert if Ipres=2
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
fct_IDP   FscaleP        
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Xc Yc Zc        
Insert if grav_ID > 0 or Freesurf=2
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
XA YA ZA        
Dir-X Dir-Y Dir-Z        

Definition

Field Contents SI Unit Example
daa_ID DAA block identifier.

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier.

(Integer, maximum 10 digits)

 
daa_title DAA block title.

(Character, maximum 100 characters)

 
surf_ID Wet surface identifier. 2 3

(Integer)

 
grav_ID /GRAV option identifier.

(Integer)

 
ρ Fluid density.

(Real)

[kgm3]
C Fluid sound speed.

(Real)

[ms] MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaadaWcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@
Pmin Pressure cutoff (< 0).

Default = -1030 (Real)

[Pa]
Xs X-coordinate of standoff point. 3

(Real)

[m]
Ys Y-coordinate of standoff point. 3

(Real)

[m]
Zs Z-coordinate of standoff point. 3

(Real)

[m]
Iform BEM solution flag.
=1 (Default)
Gauss Integration.
= 2
Analytical integration.

(Integer)

 
Ipri Printout flag level.
=1 (Default)
Reduced printout.
= 2
Full printout.

(Integer)

 
Ipres Pressure loading flag. 6
=1
Pressure computed as Pi(t)=Pmetθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaaciGGqbWaaSbaaSqaaiaacMgaaeqaaOWaaeWaaeaacaWG0baacaGLOaGaayzkaaGaeyypa0JaamiuamaaBaaaleaacaWGTbaabeaakiaadwgadaahaaWcbeqaaiabgkHiTmaalaaabaGaamiDaaqaaiabeI7aXbaaaaaaaa@43A9@ .
= 2
Input by function.

(Integer)

 
Kform Analysis flag.
=1 (Default)
DAA1 formulation
= 2
High frequency

(Integer)

 
Freesurf Free surface flag. 6
=1 (Default)
No
= 2
Yes

(Integer)

 
Afterflow Afterflow computation. 7
=1
No
= 2 (Default)
Yes

(Integer)

 
Integr Time integer flag.
=1
First order
= 2 (Default)
Second order

(Integer)

 
Pm Maximum pressure. 5

(Real)

[Pa]
θ Decay time.

(Real)

[s]
a Maximum pressure constant. 5

(Real)

 
aθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGHbWaaSbaaSqaaiabeI7aXbqabaaaaa@3A30@ Pressure decay time constant. 5

(Real)

 
fct_IDP Incident pressure function identifier.

(Integer)

 
FscaleP Ordinate (pressure) scale factor for fct_IDP.

(Real)

[Pa]
XC X-coordinate of explosive charge.

(Real)

[m]
YC Y-coordinate of explosive charge.

(Real)

[m]
ZC Z-coordinate of explosive charge.

(Real)

[m]
XA X-coordinate of point A on the free surface.

(Real)

[m]
YA Y-coordinate of point A on the free surface.

(Real)

[m]
ZA Z-coordinate of point A on the free surface.

(Real)

[m]
Dir-X X-component of the normal to the free surface plane.

(Real)

 
Dir-Y Y-component of the normal to the free surface plane.

(Real)

 
Dir-Z Z-component of the normal to the free surface plane.

(Real)

 

Comments

  1. The entire structure must be modeled. Symmetric analysis is not supported.
  2. The surface normal n MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHUbaaaa@385F@ should be pointed into the fluid.
  3. Standoff point defined with (Xs, Ys, Zs) is the location where the incident pressure wave is given at time t=0:


    Figure 1.
  4. A plane wave can be simulated using a spherical wave and putting the explosive charge far enough away.
  5. Pressure at the standoff point as a function of time is:(1)
    Pi(t)=Pmetθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaaciGGqbWaaSbaaSqaaiaacMgaaeqaaOWaaeWaaeaacaWG0baacaGLOaGaayzkaaGaeyypa0JaamiuamaaBaaaleaacaWGTbaabeaakiaadwgadaahaaWcbeqaaiabgkHiTmaalaaabaGaamiDaaqaaiabeI7aXbaaaaaaaa@43A9@
    Where,
    Pm MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbWaaSbaaSqaaiaad2gaaeqaaaaa@395B@
    Maximum pressure
    t MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWG0baaaa@3861@
    Time
    θ
    Decay time
    The maximum pressure and decay time can be calculated using:(2)
    Pm=K[W13R]a MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbWaaSbaaSqaaiaad2gaaeqaaOGaeyypa0Jaam4samaadmaabaWaaSaaaeaacaWGxbWaaWbaaSqabeaadaWccaqaaiaaigdaaeaacaaIZaaaaaaaaOqaaiaadkfaaaaacaGLBbGaayzxaaWaaWbaaSqabeaacaWGHbaaaaaa@41C4@
    (3)
    θ=KθW13[W13R]aθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH4oqCcqGH9aqpcaWGlbWaaSbaaSqaaiabeI7aXbqabaGccaWGxbWaaWbaaSqabeaadaWccaqaaiaaigdaaeaacaaIZaaaaaaakmaadmaabaWaaSaaaeaacaWGxbWaaWbaaSqabeaadaWccaqaaiaaigdaaeaacaaIZaaaaaaaaOqaaiaadkfaaaaacaGLBbGaayzxaaWaaWbaaSqabeaacaWGHbWaaSbaaWqaaiabeI7aXbqabaaaaaaa@47E9@
    W MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGxbaaaa@3844@
    Explosive mass.
    R MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGsbaaaa@383F@
    Distance to the explosion.
    K MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGlbaaaa@3838@ , α MathType@MTEF@5@5@+=feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegaaa@3792@ , Kθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGlbWaaSbaaSqaaiabeI7aXbqabaaaaa@3A1A@ and aθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGHbWaaSbaaSqaaiabeI7aXbqabaaaaa@3A30@
    Constants depending on the explosive.
    If W MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGxbaaaa@3844@ in kg, R MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGsbaaaa@383F@ in meter, Pm MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbWaaSbaaSqaaiaad2gaaeqaaaaa@395B@ in MPa and in ms.
    K MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGlbaaaa@3838@ α MathType@MTEF@5@5@+=feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegaaa@3792@ Kθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGlbWaaSbaaSqaaiabeI7aXbqabaaaaa@3A1A@ aθ MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGHbWaaSbaaSqaaiabeI7aXbqabaaaaa@3A30@
    TNT 52.12 1.180 0.0895 -0.185
    PETN 56.21 1.194 0.0860 -0.257
    HBX 53.51 1.144 0.0920 -0.247
  6. A free surface is a plane defined by a point and its normal vector.
  7. The afterflow normal velocity is calculated as:(4)
    vafterflow=cosγρR0tP(t)dt MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWG2bWaaSbaaSqaaiaadggacaWGMbGaamiDaiaadwgacaWGYbGaamOzaiaadYgacaWGVbGaam4DaaqabaGccqGH9aqpdaWcaaqaaiGacogacaGGVbGaai4Caiabeo7aNbqaaiabeg8aYjaadkfaaaWaa8qmaeaacaWGqbWaaeWaaeaacaWG0baacaGLOaGaayzkaaGaamizaiaadshaaSqaaiaaicdaaeaacaWG0baaniabgUIiYdaaaa@524C@
    P
    Fluid point.
    C
    Explosive charge point.
    S
    Standoff point.


    Figure 2.
1
Littlewood, J. de Runtz T. 2004. "USA Code". Mecalog Workshop, Sophia Antipolis, France, 2004
2
Cole, Robert H. Underwater Explosion. Princeton University Press, 1948