Commands list

×Contents and search
EXPAND ALL SORT A-Z

CFD_DETONATION

CFD

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

Parameter definition

Variable
Description
coid
Command ID
$x_d$, $y_d$, $z_d$
Detonation point or function (fcn)
quantity: Length
$t_d$
Detonation time or function (fcn)
quantity: Time
$R$
Detonation radius
quantity: Length
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
gid
Optional ID of detonation geometry
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.

If defined, the detonation geometry gid replaces the detonation point. All CFD cells inside the geometry will then ignite at time $t_d$.

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