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Changes to new generalized granular pair styles and fix wall/gran 

-Clean-up of unused variables in code
-Bug fix for single method of pair granular
-Changes to fix wall/gran to fix issues with JKR
-Doc page updates for fix wall/gran and fix wall/gran/region
This commit is contained in:
Dan S. Bolintineanu 2019-02-19 16:47:13 -07:00
parent ff795e761a
commit 4e26ca29f7
5 changed files with 85 additions and 81 deletions
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53
doc/src/fix_wall_gran.txt
View File

@ -11,18 +11,21 @@ fix wall/gran/omp command :h3
[Syntax:]
fix ID group-ID wall/gran fstyle Kn Kt gamma_n gamma_t xmu dampflag wallstyle args keyword values ... :pre
fix ID group-ID wall/gran fstyle fstyle_params wallstyle args keyword values ... :pre
ID, group-ID are documented in "fix"_fix.html command :ulb,l
wall/gran = style name of this fix command :l
fstyle = style of force interactions between particles and wall :l
possible choices: hooke, hooke/history, hertz/history :pre
Kn = elastic constant for normal particle repulsion (force/distance units or pressure units - see discussion below) :l
Kt = elastic constant for tangential contact (force/distance units or pressure units - see discussion below) :l
gamma_n = damping coefficient for collisions in normal direction (1/time units or 1/time-distance units - see discussion below) :l
gamma_t = damping coefficient for collisions in tangential direction (1/time units or 1/time-distance units - see discussion below) :l
xmu = static yield criterion (unitless value between 0.0 and 1.0e4) :l
dampflag = 0 or 1 if tangential damping force is excluded or included :l
possible choices: hooke, hooke/history, hertz/history, granular :pre
fstyle_params = parameters associated with force interaction style :l
For {hooke}, {hooke/history}, and {hertz/history}, {fstyle_params} are:
Kn = elastic constant for normal particle repulsion (force/distance units or pressure units - see discussion below)
Kt = elastic constant for tangential contact (force/distance units or pressure units - see discussion below)
gamma_n = damping coefficient for collisions in normal direction (1/time units or 1/time-distance units - see discussion below)
gamma_t = damping coefficient for collisions in tangential direction (1/time units or 1/time-distance units - see discussion below)
xmu = static yield criterion (unitless value between 0.0 and 1.0e4)
dampflag = 0 or 1 if tangential damping force is excluded or included :pre
For {granular}, {fstyle_params} are set using the same syntax as for the {pair_coeff} command of "pair_style granular"_pair_granular.html :pre
wallstyle = {xplane} or {yplane} or {zplane} or {zcylinder} :l
args = list of arguments for a particular style :l
{xplane} or {yplane} or {zplane} args = lo hi
@ -44,7 +47,10 @@ keyword = {wiggle} or {shear} :l
fix 1 all wall/gran hooke 200000.0 NULL 50.0 NULL 0.5 0 xplane -10.0 10.0
fix 1 all wall/gran hooke/history 200000.0 NULL 50.0 NULL 0.5 0 zplane 0.0 NULL
fix 2 all wall/gran hooke 100000.0 20000.0 50.0 30.0 0.5 1 zcylinder 15.0 wiggle z 3.0 2.0 :pre
fix 2 all wall/gran hooke 100000.0 20000.0 50.0 30.0 0.5 1 zcylinder 15.0 wiggle z 3.0 2.0
fix 3 all wall/gran granular hooke 1000.0 50.0 tangential linear_nohistory 1.0 0.4 zplane 0.0 NULL
fix 4 all wall/gran granular jkr 1000.0 50.0 tangential linear_history 800.0 1.0 0.5 rolling sds 500.0 200.0 0.5 twisting marshall zcylinder 15.0 wiggle z 3.0 2.0
fix 5 all wall/gran granular dmt 1000.0 50.0 0.3 10.0 tangential linear_history 800.0 0.5 0.1 roll sds 500.0 200.0 0.1 twisting marshall zplane 0.0 NULL :pre
[Description:]
@ -54,31 +60,39 @@ close enough to touch it.
The nature of the wall/particle interactions are determined by the
{fstyle} setting. It can be any of the styles defined by the
"pair_style granular"_pair_gran.html commands. Currently this is
{hooke}, {hooke/history}, or {hertz/history}. The equation for the
"pair_style gran/*"_pair_gran.html or the more general "pair_style granular"_pair_granular.html"
commands. Currently the options are {hooke}, {hooke/history}, or {hertz/history} for the former,
and {granular} with all the possible options of the associated {pair_coeff} command
for the latter. The equation for the
force between the wall and particles touching it is the same as the
corresponding equation on the "pair_style granular"_pair_gran.html doc
page, in the limit of one of the two particles going to infinite
corresponding equation on the "pair_style gran/*"_pair_gran.html
and "pair_style_granular"_pair_granular.html doc
pages, in the limit of one of the two particles going to infinite
radius and mass (flat wall). Specifically, delta = radius - r =
overlap of particle with wall, m_eff = mass of particle, and the
effective radius of contact = RiRj/Ri+Rj is just the radius of the
particle.
effective radius of contact = RiRj/Ri+Rj is set to the radius
of the particle.
The parameters {Kn}, {Kt}, {gamma_n}, {gamma_t}, {xmu} and {dampflag}
have the same meaning and units as those specified with the
"pair_style granular"_pair_gran.html commands. This means a NULL can
"pair_style gran/*"_pair_gran.html commands. This means a NULL can
be used for either {Kt} or {gamma_t} as described on that page. If a
NULL is used for {Kt}, then a default value is used where {Kt} = 2/7
{Kn}. If a NULL is used for {gamma_t}, then a default value is used
where {gamma_t} = 1/2 {gamma_n}.
All the model choices for cohesion, tangential friction, rolling friction
and twisting friction supported by the "pair_style granular"_pair_granular.html
through its {pair_coeff} command are also supported for walls. These are discussed
in greater detail on the doc page for "pair_style granular"_pair_granular.html.
Note that you can choose a different force styles and/or different
values for the 6 wall/particle coefficients than for particle/particle
values for the wall/particle coefficients than for particle/particle
interactions. E.g. if you wish to model the wall as a different
material.
NOTE: As discussed on the doc page for "pair_style
granular"_pair_gran.html, versions of LAMMPS before 9Jan09 used a
gran/*"_pair_gran.html, versions of LAMMPS before 9Jan09 used a
different equation for Hertzian interactions. This means Hertizian
wall/particle interactions have also changed. They now include a
sqrt(radius) term which was not present before. Also the previous
@ -188,6 +202,7 @@ Any dimension (xyz) that has a granular wall must be non-periodic.
"fix move"_fix_move.html,
"fix wall/gran/region"_fix_wall_gran_region.html,
"pair_style granular"_pair_gran.html
"pair_style gran/*"_pair_gran.html
"pair_style granular"_pair_granular.html
[Default:] none

43
doc/src/fix_wall_gran_region.txt
View File

@ -10,24 +10,30 @@ fix wall/gran/region command :h3
[Syntax:]
fix ID group-ID wall/gran/region fstyle Kn Kt gamma_n gamma_t xmu dampflag wallstyle regionID :pre
fix ID group-ID wall/gran/region fstyle fstyle_params wallstyle regionID :pre
ID, group-ID are documented in "fix"_fix.html command :ulb,l
wall/region = style name of this fix command :l
fstyle = style of force interactions between particles and wall :l
possible choices: hooke, hooke/history, hertz/history :pre
Kn = elastic constant for normal particle repulsion (force/distance units or pressure units - see discussion below) :l
Kt = elastic constant for tangential contact (force/distance units or pressure units - see discussion below) :l
gamma_n = damping coefficient for collisions in normal direction (1/time units or 1/time-distance units - see discussion below) :l
gamma_t = damping coefficient for collisions in tangential direction (1/time units or 1/time-distance units - see discussion below) :l
xmu = static yield criterion (unitless value between 0.0 and 1.0e4) :l
dampflag = 0 or 1 if tangential damping force is excluded or included :l
possible choices: hooke, hooke/history, hertz/history, granular :pre
fstyle_params = parameters associated with force interaction style :l
For {hooke}, {hooke/history}, and {hertz/history}, {fstyle_params} are:
Kn = elastic constant for normal particle repulsion (force/distance units or pressure units - see discussion below)
Kt = elastic constant for tangential contact (force/distance units or pressure units - see discussion below)
gamma_n = damping coefficient for collisions in normal direction (1/time units or 1/time-distance units - see discussion below)
gamma_t = damping coefficient for collisions in tangential direction (1/time units or 1/time-distance units - see discussion below)
xmu = static yield criterion (unitless value between 0.0 and 1.0e4)
dampflag = 0 or 1 if tangential damping force is excluded or included :pre
For {granular}, {fstyle_params} are set using the same syntax as for the {pair_coeff} command of "pair_style granular"_pair_granular.html :pre
wallstyle = region (see "fix wall/gran"_fix_wall_gran.html for options for other kinds of walls) :l
region-ID = region whose boundary will act as wall :l,ule
[Examples:]
fix wall all wall/gran/region hooke/history 1000.0 200.0 200.0 100.0 0.5 1 region myCone :pre
fix wall all wall/gran/region hooke/history 1000.0 200.0 200.0 100.0 0.5 1 region myCone
fix 3 all wall/gran/region granular hooke 1000.0 50.0 tangential linear_nohistory 1.0 0.4 region myBox
fix 4 all wall/gran/region granular jkr 1000.0 50.0 tangential linear_history 800.0 1.0 0.5 rolling sds 500.0 200.0 0.5 twisting marshall region myCone
fix 5 all wall/gran/region granular dmt 1000.0 50.0 0.3 10.0 tangential linear_history 800.0 0.5 0.1 roll sds 500.0 200.0 0.1 twisting marshall region myCone :pre
[Description:]
@ -122,11 +128,14 @@ to make the two faces differ by epsilon in their position.
The nature of the wall/particle interactions are determined by the
{fstyle} setting. It can be any of the styles defined by the
"pair_style granular"_pair_gran.html commands. Currently this is
{hooke}, {hooke/history}, or {hertz/history}. The equation for the
"pair_style gran/*"_pair_gran.html or the more general "pair_style granular"_pair_granular.html"
commands. Currently the options are {hooke}, {hooke/history}, or {hertz/history} for the former,
and {granular} with all the possible options of the associated {pair_coeff} command
for the latter. The equation for the
force between the wall and particles touching it is the same as the
corresponding equation on the "pair_style granular"_pair_gran.html doc
page, but the effective radius is calculated using the radius of the
corresponding equation on the "pair_style gran/*"_pair_gran.html
and "pair_style_granular"_pair_granular.html doc
pages, but the effective radius is calculated using the radius of the
particle and the radius of curvature of the wall at the contact point.
Specifically, delta = radius - r = overlap of particle with wall,
@ -140,12 +149,18 @@ particle.
The parameters {Kn}, {Kt}, {gamma_n}, {gamma_t}, {xmu} and {dampflag}
have the same meaning and units as those specified with the
"pair_style granular"_pair_gran.html commands. This means a NULL can
"pair_style gran/*"_pair_gran.html commands. This means a NULL can
be used for either {Kt} or {gamma_t} as described on that page. If a
NULL is used for {Kt}, then a default value is used where {Kt} = 2/7
{Kn}. If a NULL is used for {gamma_t}, then a default value is used
where {gamma_t} = 1/2 {gamma_n}.
All the model choices for cohesion, tangential friction, rolling friction
and twisting friction supported by the "pair_style granular"_pair_granular.html
through its {pair_coeff} command are also supported for walls. These are discussed
in greater detail on the doc page for "pair_style granular"_pair_granular.html.
Note that you can choose a different force styles and/or different
values for the 6 wall/particle coefficients than for particle/particle
interactions. E.g. if you wish to model the wall as a different

16
src/GRANULAR/fix_wall_gran.cpp
View File

@ -1021,9 +1021,8 @@ void FixWallGran::granular(double rsq, double dx, double dy, double dz,
double radius, double meff, double *history,
double *contact)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
double xtmp,ytmp,ztmp,delx,dely,delz,fx,fy,fz,nx,ny,nz;
double radi,radj,radsum,r,rinv,rsqinv;
double fx,fy,fz,nx,ny,nz;
double radsum,r,rinv;
double Reff, delta, dR, dR2;
double vr1,vr2,vr3,vnnr,vn1,vn2,vn3,vt1,vt2,vt3;
@ -1035,17 +1034,17 @@ void FixWallGran::granular(double rsq, double dx, double dy, double dz,
double Fne, Ft, Fdamp, Fntot, Fncrit, Fscrit, Frcrit;
double fs, fs1, fs2, fs3;
double mi,mj,damp,ccel,tor1,tor2,tor3;
double tor1,tor2,tor3;
double relrot1,relrot2,relrot3,vrl1,vrl2,vrl3,vrlmag,vrlmaginv;
//For JKR
double R2, coh, F_pulloff, delta_pulloff, dist_pulloff, a, a2, E;
double R2, coh, F_pulloff, a, a2, E;
double t0, t1, t2, t3, t4, t5, t6;
double sqrt1, sqrt2, sqrt3, sqrt4;
double sqrt1, sqrt2, sqrt3;
//Rolling
double k_roll, damp_roll;
double roll1, roll2, roll3, torroll1, torroll2, torroll3;
double torroll1, torroll2, torroll3;
double rollmag, rolldotn, scalefac;
double fr, fr1, fr2, fr3;
@ -1055,9 +1054,6 @@ void FixWallGran::granular(double rsq, double dx, double dy, double dz,
double tortwist1, tortwist2, tortwist3;
double shrmag,rsht;
int *ilist,*jlist,*numneigh,**firstneigh;
int *touch,**firsttouch;
double *allhistory,**firsthistory;
r = sqrt(rsq);
radsum = rwall + radius;

4
src/GRANULAR/pair_gran_hooke_history.cpp
View File

@ -349,10 +349,6 @@ void PairGranHookeHistory::settings(int narg, char **arg)
{
if (narg != 6) error->all(FLERR,"Illegal pair_style command");
kn = force->numeric(FLERR,arg[0]);
if (strcmp(arg[1],"NULL") == 0) kt = kn * 2.0/7.0;
else kt = force->numeric(FLERR,arg[1]);

50
src/GRANULAR/pair_granular.cpp
View File

@ -130,7 +130,7 @@ void PairGranular::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
double xtmp,ytmp,ztmp,delx,dely,delz,fx,fy,fz,nx,ny,nz;
double radi,radj,radsum,rsq,r,rinv,rsqinv;
double radi,radj,radsum,rsq,r,rinv;
double Reff, delta, dR, dR2;
double vr1,vr2,vr3,vnnr,vn1,vn2,vn3,vt1,vt2,vt3;
@ -140,19 +140,19 @@ void PairGranular::compute(int eflag, int vflag)
double knfac, damp_normal, damp_normal_prefactor;
double k_tangential, damp_tangential;
double Fne, Ft, Fdamp, Fntot, Fncrit, Fscrit, Frcrit;
double fs, fs1, fs2, fs3;
double fs, fs1, fs2, fs3, tor1, tor2, tor3;
double mi,mj,meff,damp,ccel,tor1,tor2,tor3;
double relrot1,relrot2,relrot3,vrl1,vrl2,vrl3,vrlmag,vrlmaginv;
double mi,mj,meff;
double relrot1,relrot2,relrot3,vrl1,vrl2,vrl3;
//For JKR
double R2, coh, F_pulloff, delta_pulloff, dist_pulloff, a, a2, E;
double t0, t1, t2, t3, t4, t5, t6;
double sqrt1, sqrt2, sqrt3, sqrt4;
double sqrt1, sqrt2, sqrt3;
//Rolling
double k_roll, damp_roll;
double roll1, roll2, roll3, torroll1, torroll2, torroll3;
double torroll1, torroll2, torroll3;
double rollmag, rolldotn, scalefac;
double fr, fr1, fr2, fr3;
@ -204,7 +204,6 @@ void PairGranular::compute(int eflag, int vflag)
double *rmass = atom->rmass;
int *mask = atom->mask;
int nlocal = atom->nlocal;
int newton_pair = force->newton_pair;
inum = list->inum;
ilist = list->ilist;
@ -465,9 +464,6 @@ void PairGranular::compute(int eflag, int vflag)
vrl1 = Reff*(relrot2*nz - relrot3*ny); //- 0.5*((radj-radi)/radsum)*vtr1;
vrl2 = Reff*(relrot3*nx - relrot1*nz); //- 0.5*((radj-radi)/radsum)*vtr2;
vrl3 = Reff*(relrot1*ny - relrot2*nx); //- 0.5*((radj-radi)/radsum)*vtr3;
vrlmag = sqrt(vrl1*vrl1+vrl2*vrl2+vrl3*vrl3);
if (vrlmag != 0.0) vrlmaginv = 1.0/vrlmag;
else vrlmaginv = 0.0;
int rhist0 = roll_history_index;
int rhist1 = rhist0 + 1;
@ -1192,12 +1188,12 @@ double PairGranular::single(int i, int j, int itype, int jtype,
double rsq, double factor_coul, double factor_lj, double &fforce)
{
double radi,radj,radsum;
double r,rinv,rsqinv,delx,dely,delz, nx, ny, nz, Reff;
double r,rinv,delx,dely,delz, nx, ny, nz, Reff;
double dR, dR2;
double vr1,vr2,vr3,vnnr,vn1,vn2,vn3,vt1,vt2,vt3,wr1,wr2,wr3;
double vtr1,vtr2,vtr3,vrel;
double mi,mj,meff,damp,ccel,tor1,tor2,tor3;
double relrot1,relrot2,relrot3,vrl1,vrl2,vrl3,vrlmag,vrlmaginv;
double mi,mj,meff;
double relrot1,relrot2,relrot3,vrl1,vrl2,vrl3;
double knfac, damp_normal, damp_normal_prefactor;
double k_tangential, damp_tangential;
@ -1207,25 +1203,22 @@ double PairGranular::single(int i, int j, int itype, int jtype,
//For JKR
double R2, coh, F_pulloff, delta_pulloff, dist_pulloff, a, a2, E;
double delta, t0, t1, t2, t3, t4, t5, t6;
double sqrt1, sqrt2, sqrt3, sqrt4;
double sqrt1, sqrt2, sqrt3;
//Rolling
double k_roll, damp_roll;
double roll1, roll2, roll3, torroll1, torroll2, torroll3;
double rollmag, rolldotn, scalefac;
double rollmag;
double fr, fr1, fr2, fr3;
//Twisting
double k_twist, damp_twist, mu_twist;
double signtwist, magtwist, magtortwist, Mtcrit;
double tortwist1, tortwist2, tortwist3;
double shrmag,rsht;
double shrmag;
int jnum;
int *ilist,*jlist,*numneigh,**firstneigh;
int *touch,**firsttouch;
double *history,*allhistory,**firsthistory;
int *jlist;
double *history,*allhistory;
double *radius = atom->radius;
radi = radius[i];
@ -1312,8 +1305,6 @@ double PairGranular::single(int i, int j, int itype, int jtype,
// if I or J part of rigid body, use body mass
// if I or J is frozen, meff is other particle
int *type = atom->type;
mi = rmass[i];
mj = rmass[j];
if (fix_rigid) {
@ -1348,11 +1339,11 @@ double PairGranular::single(int i, int j, int itype, int jtype,
else{
knfac = E;
a = sqrt(dR);
Fne = knfac*delta;
if (normal_model[itype][jtype] != HOOKE){
Fne *= a;
knfac *= a;
}
Fne = knfac*delta;
if (normal_model[itype][jtype] == DMT)
Fne -= 4*MY_PI*normal_coeffs[itype][jtype][3]*Reff;
}
@ -1471,9 +1462,6 @@ double PairGranular::single(int i, int j, int itype, int jtype,
vrl1 = Reff*(relrot2*nz - relrot3*ny); //- 0.5*((radj-radi)/radsum)*vtr1;
vrl2 = Reff*(relrot3*nx - relrot1*nz); //- 0.5*((radj-radi)/radsum)*vtr2;
vrl3 = Reff*(relrot1*ny - relrot2*nx); //- 0.5*((radj-radi)/radsum)*vtr3;
vrlmag = sqrt(vrl1*vrl1+vrl2*vrl2+vrl3*vrl3);
if (vrlmag != 0.0) vrlmaginv = 1.0/vrlmag;
else vrlmaginv = 0.0;
int rhist0 = roll_history_index;
int rhist1 = rhist0 + 1;
@ -1484,8 +1472,6 @@ double PairGranular::single(int i, int j, int itype, int jtype,
history[rhist1]*history[rhist1] +
history[rhist2]*history[rhist2]);
rolldotn = history[rhist0]*nx + history[rhist1]*ny + history[rhist2]*nz;
k_roll = roll_coeffs[itype][jtype][0];
damp_roll = roll_coeffs[itype][jtype][1];
fr1 = -k_roll*history[rhist0] - damp_roll*vrl1;
@ -1498,9 +1484,6 @@ double PairGranular::single(int i, int j, int itype, int jtype,
fr = sqrt(fr1*fr1 + fr2*fr2 + fr3*fr3);
if (fr > Frcrit) {
if (rollmag != 0.0) {
history[rhist0] = -1.0/k_roll*(Frcrit*fr1/fr + damp_roll*vrl1);
history[rhist1] = -1.0/k_roll*(Frcrit*fr2/fr + damp_roll*vrl2);
history[rhist2] = -1.0/k_roll*(Frcrit*fr3/fr + damp_roll*vrl3);
fr1 *= Frcrit/fr;
fr2 *= Frcrit/fr;
fr3 *= Frcrit/fr;
@ -1528,7 +1511,6 @@ double PairGranular::single(int i, int j, int itype, int jtype,
signtwist = (magtwist > 0) - (magtwist < 0);
Mtcrit = mu_twist*Fncrit;//critical torque (eq 44)
if (fabs(magtortwist) > Mtcrit) {
history[twist_history_index] = 1.0/k_twist*(Mtcrit*signtwist - damp_twist*magtwist);
magtortwist = -Mtcrit * signtwist; //eq 34
}
}
@ -1621,7 +1603,7 @@ double PairGranular::mix_geom(double valii, double valjj)
double PairGranular::pulloff_distance(double radi, double radj, int itype, int jtype)
{
double E, coh, a, delta_pulloff, Reff;
double E, coh, a, Reff;
Reff = radi*radj/(radi+radj);
if (Reff <= 0) return 0;
coh = normal_coeffs[itype][itype][3];