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CFD_DETONATION

CFD

*CFD_DETONATION
"Optional title"
coid
$x_d$, $y_d$, $z_d$, $t_d$, $R$, path, pid

Parameter definition

Variable
Description
coid
Command ID
$x_d$, $y_d$, $z_d$
Detonation point or function (fcn)
$t_d$
Detonation time or function (fcn)
$R$
Detonation radius
default: not used
path
Detonation path
options:
0 $\rightarrow$ radial detonation path
1 $\rightarrow$ detonation path that accounts for obsacles and geometrical features
pid
Part ID (defining region in space where detonation will occur)
default: not used

Description

CFD detonation point definition (see CFD_DOMAIN). The optional parameter $R$ limits the distance the detonation front is allowed to propagate through programmed burn.

It is possible to model undetonated explosives with Finite Elements (FE) and then switch to a CFD formulation (programmed burn) at detonation. This done by setting the flag follow=1 in CFD_HE and by specifying the FE part ID (pid) in this command. Further, it is necessary to deactivate the elements with ACTIVATE_ELEMENTS on the same signal as the triggering of the detonation.

Example

FE to CFD switch

Switching from Finite Element model of explosive to CFD at detonation time.

*UNIT_SYSTEM SI *PARAMETER hc = 0.1, "Explosive charge height" Rc = 0.03, "Explosive charge radius" Rf = 0.005, "Fragment radius" v0 = 1000.0, "Fragment velocity" tend = 0.0001, "Terminattion time" dc = 0.002, "CFD cell size" follow = 1, "Let undetonated CFD explosive follow FE mesh" pid = 11 "FE explosive part ID" # # --- TIME --- # *TIME [%tend] # # --- MESH --- # *COMPONENT_CYLINDER "Explosive charge" 1, [%pid], 20, 8 0, 0, 0, 0, 0, [%hc], [%Rc] *COMPONENT_SPHERE "Fragment" 2, 12, 3 [-1.5*%Rc], 0, [0.7*%hc], [%Rf] # # --- MATERIAL --- # *MAT_METAL "Explosive" 1, 1717.0, 1.0e9, 0.49, 0, 0, 1 1 *FUNCTION 1 5.0e7 *EOS_GRUNEISEN 1, 1.5, 2.0 *MAT_RIGID "Fragment" 2, 7800.0 # # --- PART --- # *PART "Explosive" [%pid], 1 "Fragment" 12, 2 # # --- CONTACT --- # *CONTACT "all to all" 1 ALL, 0, ALL, 0 # # --- INITIAL VELOCITY --- # *INITIAL_VELOCITY P, 12, [%v0] # # --- BC --- # *BC_SYMMETRY Z # # --- CFD --- # *CFD_DOMAIN 1 ALL, 0, [%dc], 1, 1 -0.1, -0.1, 0, 0.1, 0.1, 0.2 0, 0, 1, 0, 0, 0 *CFD_HE "Explosive" 1 COMPB, 20, [%follow] *GEOMETRY_PART 20 [%pid] # # --- DETONATION and DEACTIVATION --- # *ACTIVATE_ELEMENTS 1, P, [%pid], 0, fcn(100) *CFD_DETONATION 1 fcn(101), fcn(102), fcn(103), fcn(100), 0, 0, [%pid] *FUNCTION "Detonation criterion" 100 epsp_part(%pid, 0) - 0.5 *FUNCTION "x-coordinate at max plastic strain" 101 epsp_part(%pid, 1) *FUNCTION "y-coordinate at max plastic strain" 102 epsp_part(%pid, 2) *FUNCTION "z-coordinate at max plastic strain" 103 epsp_part(%pid, 3) *END