/* ---------------------------------------------------------------------- LIGGGHTS - LAMMPS Improved for General Granular and Granular Heat Transfer Simulations LIGGGHTS is part of the CFDEMproject www.liggghts.com | www.cfdem.com Copyright 2018- JKU Linz LIGGGHTS is based on LAMMPS LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator http://lammps.sandia.gov, Sandia National Laboratories Steve Plimpton, sjplimp@sandia.gov This software is distributed under the GNU General Public License. See the README file in the top-level directory. ------------------------------------------------------------------------- */ /* ---------------------------------------------------------------------- Contributing authors: Daniel Queteschiner (JKU Linz) ------------------------------------------------------------------------- */ #ifdef TANGENTIAL_MODEL TANGENTIAL_MODEL(TANGENTIAL_INCREMENTAL_HISTORY,incremental_history,2) #else #ifndef TANGENTIAL_MODEL_INCREMENTAL_HISTORY_H_ #define TANGENTIAL_MODEL_INCREMENTAL_HISTORY_H_ #include "contact_models.h" #include #include "update.h" #include "global_properties.h" #include "atom.h" namespace LIGGGHTS { namespace ContactModels { #define TRACK_TANGENTIAL_OVERLAP #define SCALE_OLD_TANGENTIAL_FORCE template<> class TangentialModel : protected Pointers { double ** coeffFrict; int history_offset; public: static const int MASK = CM_CONNECT_TO_PROPERTIES | CM_COLLISION | CM_NO_COLLISION; TangentialModel(LAMMPS * lmp, IContactHistorySetup * hsetup) : Pointers(lmp), coeffFrict(NULL) { #ifdef TRACK_TANGENTIAL_OVERLAP history_offset = hsetup->add_history_value("shearx", "1"); hsetup->add_history_value("sheary", "1"); hsetup->add_history_value("shearz", "1"); hsetup->add_history_value("shearfx", "1"); hsetup->add_history_value("shearfy", "1"); hsetup->add_history_value("shearfz", "1"); #else history_offset = hsetup->add_history_value("shearfx", "1"); hsetup->add_history_value("shearfy", "1"); hsetup->add_history_value("shearfz", "1"); #endif #ifdef SCALE_OLD_TANGENTIAL_FORCE hsetup->add_history_value("kt", "0"); hsetup->add_history_value("Fn", "1"); #endif if (comm->me == 0 && screen) fprintf(screen, "TANGENTIAL/INCREMENTAL_HISTORY loaded\n"); } inline void registerSettings(Settings&){} inline void connectToProperties(PropertyRegistry & registry) { registry.registerProperty("coeffFrict", &MODEL_PARAMS::createCoeffFrict); registry.connect("coeffFrict", coeffFrict,"tangential_model history"); } inline void collision(CollisionData & cdata, ForceData & i_forces, ForceData & j_forces) { // normal forces = Hookian contact + normal velocity damping const double enx = cdata.en[0]; const double eny = cdata.en[1]; const double enz = cdata.en[2]; // shear history effects if (cdata.touch) *cdata.touch |= TOUCH_TANGENTIAL_MODEL; #ifdef TRACK_TANGENTIAL_OVERLAP double * const shear = &cdata.contact_history[history_offset]; double * const Ft_shear = &cdata.contact_history[history_offset+3]; #ifdef SCALE_OLD_TANGENTIAL_FORCE double* const kt_old = &cdata.contact_history[history_offset+6]; double* const Fn_old = &cdata.contact_history[history_offset+7]; #endif #else double * const Ft_shear = &cdata.contact_history[history_offset]; #ifdef SCALE_OLD_TANGENTIAL_FORCE double* const kt_old = &cdata.contact_history[history_offset+3]; double* const Fn_old = &cdata.contact_history[history_offset+4]; #endif #endif if (cdata.shearupdate && cdata.computeflag) { const double dt = update->dt; const double deltatx = cdata.vtr1 * dt; const double deltaty = cdata.vtr2 * dt; const double deltatz = cdata.vtr3 * dt; #ifdef TRACK_TANGENTIAL_OVERLAP shear[0] += deltatx; shear[1] += deltaty; shear[2] += deltatz; // project vector into normal plane and // subtract normal component from shear displacement vector const double shear_dot_en = shear[0]*enx + shear[1]*eny + shear[2]*enz; shear[0] -= shear_dot_en * enx; shear[1] -= shear_dot_en * eny; shear[2] -= shear_dot_en * enz; #endif const double Ft_shear_dot_en = Ft_shear[0]*enx + Ft_shear[1]*eny + Ft_shear[2]*enz; Ft_shear[0] -= Ft_shear_dot_en * enx; Ft_shear[1] -= Ft_shear_dot_en * eny; Ft_shear[2] -= Ft_shear_dot_en * enz; const double kt = cdata.kt; const double gammat = cdata.gammat; const double xmu = coeffFrict[cdata.itype][cdata.jtype]; #ifdef SCALE_OLD_TANGENTIAL_FORCE // rescale Ft_shear, see // Thornton et al., Powder Technol. 233 (2013) 30-46 if((cdata.Fn - Fn_old[0]) < 0. && kt_old[0] > 0. && kt_old[0] != kt) { const double kt_ratio = kt/kt_old[0]; Ft_shear[0] *= kt_ratio; Ft_shear[1] *= kt_ratio; Ft_shear[2] *= kt_ratio; } kt_old[0] = kt; Fn_old[0] = cdata.Fn; #endif Ft_shear[0] -= kt * deltatx + gammat * cdata.vtr1; Ft_shear[1] -= kt * deltaty + gammat * cdata.vtr2; Ft_shear[2] -= kt * deltatz + gammat * cdata.vtr3; // rescale tangential forces if needed const double Ft_shear_mag = sqrt(Ft_shear[0]*Ft_shear[0] + Ft_shear[1]*Ft_shear[1] + Ft_shear[2]*Ft_shear[2]); const double Ft_friction = xmu * fabs(cdata.Fn); if (Ft_shear_mag > Ft_friction) { if (Ft_shear_mag > 0.0) { const double ratio = Ft_friction / Ft_shear_mag; Ft_shear[0] *= ratio; Ft_shear[1] *= ratio; Ft_shear[2] *= ratio; } } } const double Ft1 = Ft_shear[0]; const double Ft2 = Ft_shear[1]; const double Ft3 = Ft_shear[2]; // forces & torques const double tor1 = eny * Ft3 - enz * Ft2; const double tor2 = enz * Ft1 - enx * Ft3; const double tor3 = enx * Ft2 - eny * Ft1; double torque_i[3] = {}; double torque_j[3] = {}; #ifdef NONSPHERICAL_ACTIVE_FLAG if (cdata.is_non_spherical) { double xci[3] = {}; double Ft_i[3] = { Ft1, Ft2, Ft3 }; vectorSubtract3D(cdata.contact_point, atom->x[cdata.i], xci); vectorCross3D(xci, Ft_i, torque_i); if (!cdata.is_wall) { double xcj[3] = {}; vectorSubtract3D(cdata.contact_point, atom->x[cdata.j], xcj); double Ft_j[3] = { -Ft1, -Ft2, -Ft3 }; vectorCross3D(xcj, Ft_j, torque_j); } } else #endif { torque_i[0] = -cdata.cri * tor1; torque_i[1] = -cdata.cri * tor2; torque_i[2] = -cdata.cri * tor3; if (!cdata.is_wall) { torque_j[0] = -cdata.crj * tor1; torque_j[1] = -cdata.crj * tor2; torque_j[2] = -cdata.crj * tor3; } } // return resulting forces if (cdata.is_wall) { const double area_ratio = cdata.area_ratio; i_forces.delta_F[0] += Ft1 * area_ratio; i_forces.delta_F[1] += Ft2 * area_ratio; i_forces.delta_F[2] += Ft3 * area_ratio; i_forces.delta_torque[0] += torque_i[0] * area_ratio; i_forces.delta_torque[1] += torque_i[1] * area_ratio; i_forces.delta_torque[2] += torque_i[2] * area_ratio; } else { i_forces.delta_F[0] += Ft1; i_forces.delta_F[1] += Ft2; i_forces.delta_F[2] += Ft3; i_forces.delta_torque[0] += torque_i[0]; i_forces.delta_torque[1] += torque_i[1]; i_forces.delta_torque[2] += torque_i[2]; j_forces.delta_F[0] += -Ft1; j_forces.delta_F[1] += -Ft2; j_forces.delta_F[2] += -Ft3; j_forces.delta_torque[0] += torque_j[0]; j_forces.delta_torque[1] += torque_j[1]; j_forces.delta_torque[2] += torque_j[2]; } } inline void noCollision(ContactData & cdata, ForceData&, ForceData&) { // unset non-touching neighbors if (cdata.touch) *cdata.touch &= ~TOUCH_TANGENTIAL_MODEL; if (!cdata.contact_history) return; double * const shear = &cdata.contact_history[history_offset]; int i = 0; shear[i++] = 0.0; shear[i++] = 0.0; shear[i++] = 0.0; #ifdef TRACK_TANGENTIAL_OVERLAP shear[i++] = 0.0; shear[i++] = 0.0; shear[i++] = 0.0; #endif #ifdef SCALE_OLD_TANGENTIAL_FORCE shear[i++] = 0.0; shear[i++] = 0.0; #endif } inline void beginPass(CollisionData&, ForceData&, ForceData&){} inline void endPass(CollisionData&, ForceData&, ForceData&){} }; } } #endif // TANGENTIAL_MODEL_INCREMENTAL_HISTORY_H_ #endif