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// 2024 © Benjamin Dedieu <benjamin.dedieu@proton.me>
#include "TimeAverager.hpp"
#include <lib/high-precision/Constants.hpp>
#include <core/Scene.hpp>
#include <pkg/common/NormShearPhys.hpp>
#include <pkg/common/Sphere.hpp>
#include <pkg/dem/DemXDofGeom.hpp>
#include <boost/unordered_map.hpp>
// The TimeAverager class is used to average data over time for specific sphere identified by ids.
// See description in TimeAverager.hpp
namespace yade {
YADE_PLUGIN((TimeAverager));
// PUBLIC METHODS
Vector3r TimeAverager::getPos(Body::id_t id) const { return getValueFromMap(pos, id); }
Vector3r TimeAverager::getVel(Body::id_t id) const { return getValueFromMap(vel, id); }
Vector3r TimeAverager::getAngVel(Body::id_t id) const { return getValueFromMap(angVel, id); }
Vector3r TimeAverager::getForce(Body::id_t id) const { return getValueFromMap(force, id); }
Vector3r TimeAverager::getTorque(Body::id_t id) const { return getValueFromMap(torque, id); }
Real TimeAverager::getNbContact(Body::id_t id) const { return getValueFromMap(nbContact, id); }
Vector3r TimeAverager::getContactForce(Body::id_t id) const { return getValueFromMap(contactForce, id); }
Vector3r TimeAverager::getContactTorque(Body::id_t id) const { return getValueFromMap(contactTorque, id); }
vector<Vector3r> TimeAverager::getContactForceField(Body::id_t id) const
{
if (computeContactForceField) { return getValueFromMap(contactForceField, id); }
throw std::runtime_error("No value to retrieve for contactForceField since computeContactForceField is false.");
}
void TimeAverager::initialization()
{
scene->forces.sync();
FOREACH(Body::id_t id, ids)
{
const shared_ptr<Body>& b = Body::byId(id, scene);
if (!b) continue;
pos[id] = b->state->pos;
vel[id] = b->state->vel;
angVel[id] = b->state->angVel;
force[id] = scene->forces.getForce(id);
torque[id] = scene->forces.getTorque(id);
nbContact[id] = getInstantNbContact(b);
contactForce[id] = getInstantContactForce(b);
contactTorque[id] = getInstantContactTorque(b);
if (computeContactForceField) { contactForceField[id] = getInstantContactForceField(b); }
}
tAccu = 0;
}
void TimeAverager::action()
{
const Real& dt = scene->dt;
scene->forces.sync();
FOREACH(Body::id_t id, ids)
{
const shared_ptr<Body>& b = Body::byId(id, scene);
if (!b) continue;
pos[id] = updateAverage(pos[id], b->state->pos, dt);
vel[id] = updateAverage(vel[id], b->state->vel, dt);
angVel[id] = updateAverage(angVel[id], b->state->angVel, dt);
force[id] = updateAverage(force[id], scene->forces.getForce(id), dt);
torque[id] = updateAverage(torque[id], scene->forces.getTorque(id), dt);
nbContact[id] = updateAverage(nbContact[id], getInstantNbContact(b), dt);
contactForce[id] = updateAverage(contactForce[id], getInstantContactForce(b), dt);
contactTorque[id] = updateAverage(contactTorque[id], getInstantContactTorque(b), dt);
if (computeContactForceField) {
// Can't average directly vector<Vector3r>, so we do it element by element
vector<Vector3r> instantContactForceField = getInstantContactForceField(b);
for (size_t i = 0; i < contactForceField[id].size(); ++i) {
contactForceField[id][i] = updateAverage(contactForceField[id][i], instantContactForceField[i], dt);
}
}
}
tAccu += dt;
}
// PRIVATE METHODS
template <typename T> T TimeAverager::updateAverage(const T& averagedVal, const T& instantVal, const Real& dt) const
{
if (tAccu + dt == 0) return averagedVal;
return (tAccu * averagedVal + dt * instantVal) / (tAccu + dt);
}
template <typename T> T TimeAverager::getValueFromMap(const boost::unordered_map<Body::id_t, T>& mapObject, Body::id_t id) const
{
auto it = mapObject.find(id);
if (it == mapObject.end()) { throw std::runtime_error("Particle ID not found in map"); }
return it->second;
}
Real TimeAverager::getInstantNbContact(const shared_ptr<Body>& b) const
{
// Get number of contacts from size of interaction map object and convert to floating point
return b->intrs.size();
}
Vector3r TimeAverager::getInstantContactForce(const shared_ptr<Body>& b) const
{
Vector3r instantContactForce = Vector3r::Zero();
for (Body::MapId2IntrT::iterator it = b->intrs.begin(), end = b->intrs.end(); it != end; ++it) {
const shared_ptr<Interaction>& I = (*it).second;
if (!I->isReal()) continue;
NormShearPhys* phys = YADE_CAST<NormShearPhys*>(I->phys.get());
instantContactForce += phys->shearForce + phys->normalForce;
}
return instantContactForce;
}
Vector3r TimeAverager::getInstantContactTorque(const shared_ptr<Body>& b) const
{
Vector3r instantContactTorque = Vector3r::Zero();
for (Body::MapId2IntrT::iterator it = b->intrs.begin(), end = b->intrs.end(); it != end; ++it) {
const shared_ptr<Interaction>& I = (*it).second;
if (!I->isReal()) continue;
NormShearPhys* phys = YADE_CAST<NormShearPhys*>(I->phys.get());
GenericSpheresContact* geom = YADE_CAST<GenericSpheresContact*>(I->geom.get());
Vector3r relativePos = geom->contactPoint - b->state->pos;
Vector3r forceSum = phys->shearForce + phys->normalForce;
instantContactTorque += relativePos.cross(forceSum);
}
return instantContactTorque;
}
vector<Vector3r> TimeAverager::getInstantContactForceField(const shared_ptr<Body>& b) const
{
vector<Vector3r> instantContactForceField(grid.size(), Vector3r::Zero());
// Loop on interaction map
for (Body::MapId2IntrT::iterator it = b->intrs.begin(), end = b->intrs.end(); it != end; ++it) {
// Retrieve Interaction object from the current map pair
const shared_ptr<Interaction>& I = (*it).second;
if (!I->isReal()) continue;
// Get physics and geom object from the interaction
NormShearPhys* phys = YADE_CAST<NormShearPhys*>(I->phys.get());
GenericSpheresContact* geom = YADE_CAST<GenericSpheresContact*>(I->geom.get());
// Compute Gaussian kernel weights associated to each grid point, according to the distance between
// the contact point and the grid point, and compute the sum of the weights for normalization purpose.
vector<Real> weights(grid.size());
Real normalizationFactor = 0.0;
for (size_t i = 0; i < grid.size(); i++) {
Real distanceToContact = (b->state->pos + grid[i] - geom->contactPoint).norm();
weights[i] = exp(-pow(distanceToContact, 2) / (2 * pow(sigma, 2)));
normalizationFactor += weights[i];
}
// Distribute the contact force on the grid
if (normalizationFactor > 0) { // Safety check for the division
for (size_t i = 0; i < grid.size(); i++) {
instantContactForceField[i] += (phys->shearForce + phys->normalForce) * weights[i] / normalizationFactor;
}
}
}
return instantContactForceField;
}
} // namespace yade
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