Description

Main Chrono::Granular system class used to control and dispatch the GPU sphere-only solver.

#include <ChGranular.h>

Inheritance diagram for chrono::granular::ChSystemGranularSMC:

Collaboration diagram for chrono::granular::ChSystemGranularSMC:

Public Member Functions
	ChSystemGranularSMC (float sphere_rad, float density, float3 boxDims)
	Construct granular system with given sphere radius, density, and big domain dimensions.

unsigned int	get_SD_count () const
	Return number of subdomains in the big domain.

void	set_gravitational_acceleration (float xVal, float yVal, float zVal)
	Set acceleration of gravity.

size_t	getNumSpheres () const
	Return total number of spheres in the system.

size_t	estimateMemUsage () const
	Roughly estimates the total amount of memory used by the system.

size_t	Create_BC_Sphere (float center[3], float radius, bool outward_normal, bool track_forces)
	Create an axis-aligned sphere boundary condition.

size_t	Create_BC_Cone_Z (float cone_tip[3], float slope, float hmax, float hmin, bool outward_normal, bool track_forces)
	Create an z-axis aligned cone boundary condition.

size_t	Create_BC_Plane (float plane_pos[3], float plane_normal[3], bool track_forces)
	Create plane boundary condition.

size_t	Create_BC_Cyl_Z (float center[3], float radius, bool outward_normal, bool track_forces)
	Create an z-axis aligned cylinder boundary condition.

void	createWallBCs ()
	Create big domain walls out of plane boundary conditions.

bool	disable_BC_by_ID (size_t BC_id)
	Disable a boundary condition by its ID, returns false if the BC does not exist.

bool	enable_BC_by_ID (size_t BC_id)
	Enable a boundary condition by its ID, returns false if the BC does not exist.

bool	set_BC_offset_function (size_t BC_id, const GranPositionFunction &offset_function)
	Enable a boundary condition by its ID, returns false if the BC does not exist.

bool	getBCReactionForces (size_t BC_id, float forces[3]) const
	Get the reaction forces on a boundary by ID, returns false if the forces are invalid (bad BC ID)

void	setOutputMode (GRAN_OUTPUT_MODE mode)
	Set the output mode of the simulation.

void	setVerbose (GRAN_VERBOSITY level)
	Set simualtion verbosity – used to check on very large, slow simulations or debug.

void	setOutputFlags (unsigned char flags)
	Set output settings bit flags by bitwise ORing settings in GRAN_OUTPUT_FLAGS.

void	set_fixed_stepSize (float size_UU)
	Set timestep size.

void	disableMinLength ()
	Ensure that the deformation-based length unit is used.

void	set_timeIntegrator (GRAN_TIME_INTEGRATOR new_integrator)
	Set the time integration scheme for the system.

void	set_friction_mode (GRAN_FRICTION_MODE new_mode)
	Set friction formulation. More...

void	set_rolling_mode (GRAN_ROLLING_MODE new_mode)
	Set rolling resistence formulation. More...

double	get_max_z () const
	Get the max z position of the spheres, allows easier co-simulation.

virtual double	advance_simulation (float duration)
	Advance simulation by duration in user units, return actual duration elapsed Requires initialize() to have been called.

virtual void	initialize ()
	Initialize simulation so that it can be advanced Must be called before advance_simulation and after simulation parameters are set.

void	set_static_friction_coeff_SPH2SPH (float mu)
	Set sphere-to-sphere static friction coefficient.

void	set_static_friction_coeff_SPH2WALL (float mu)
	Set sphere-to-wall static friction coefficient.

void	set_rolling_coeff_SPH2SPH (float mu)
	Set sphere-to-sphere rolling friction coefficient – units and use vary by rolling friction mode.

void	set_rolling_coeff_SPH2WALL (float mu)
	Set sphere-to-wall rolling friction coefficient – units and use vary by rolling friction mode.

void	set_spinning_coeff_SPH2SPH (float mu)
	Set sphere-to-sphere spinning friction coefficient – units and use vary by spinning friction mode.

void	set_spinning_coeff_SPH2WALL (float mu)
	Set sphere-to-wall spinning friction coefficient – units and use vary by spinning friction mode.

void	set_K_n_SPH2SPH (double someValue)
	Set sphere-to-sphere normal contact stiffness.

void	set_K_n_SPH2WALL (double someValue)
	Set sphere-to-wall normal contact stiffness.

void	set_Gamma_n_SPH2SPH (double someValue)
	Set sphere-to-sphere normal damping coefficient.

void	set_Gamma_n_SPH2WALL (double someValue)
	Set sphere-to-wall normal damping coefficient.

void	set_K_t_SPH2SPH (double someValue)
	Set sphere-to-sphere tangent contact stiffness.

void	set_Gamma_t_SPH2SPH (double someValue)
	Set sphere-to-sphere tangent damping coefficient.

void	set_K_t_SPH2WALL (double someValue)
	Set sphere-to-wall tangent contact stiffness.

void	set_Gamma_t_SPH2WALL (double someValue)
	Set sphere-to-wall tangent damping coefficient.

void	set_Cohesion_ratio (float someValue)
	Set the ratio of cohesion to gravity for monodisperse spheres. Assumes a constant cohesion model.

void	set_Adhesion_ratio_S2W (float someValue)
	Set the ratio of adhesion to gravity for sphere to wall. Assumes a constant cohesion model.

void	set_BD_Fixed (bool fixed)
	Set the big domain to be fixed or not; if fixed it will ignore any given position functions.

void	setParticlePositions (const std::vector< float3 > &points, const std::vector< float3 > &vels=std::vector< float3 >(), const std::vector< float3 > &ang_vels=std::vector< float3 >())
	Set initial particle positions. MUST be called only once and MUST be called before initialize.

void	setParticleFixed (const std::vector< bool > &fixed)
	Set particle fixity. MUST be called only once and MUST be called before initialize.

float3	getPosition (int nSphere)
	return particle position given sphere index

float	getAbsVelocity (int nSphere)

float3	getVelocity (int nSphere)

float3	getAngularVelocity (int nSphere)

int	getNumContacts ()

float3	Get_BC_Plane_Position (size_t plane_id)

void	setBDWallsMotionFunction (const GranPositionFunction &pos_fn)
	Prescribe the motion of the big domain, allows wavetank-style simulations.

void	setRecordingContactInfo (bool record)

void	setPsiFactors (unsigned int psi_T_new, unsigned int psi_L_new, float psi_R_new=1.f)
	Set tuning psi factors for tuning the non-dimensionalization.

void	checkSDCounts (std::string ofile, bool write_out, bool verbose) const
	Copy back the subdomain device data and save it to a file for error checking on the priming kernel.

void	writeFile (std::string ofile) const
	Writes out particle positions according to the system output mode.

void	writeContactInfoFile (std::string ofile) const
	Writes out contact info.

void	setMaxSafeVelocity_SU (float max_vel)
	Safety check velocity to ensure the simulation is still stable.

Public Attributes
GranPositionFunction	BDOffsetFunction
	The offset function for the big domain walls.

Protected Member Functions
int3	getSDTripletFromID (unsigned int SD_ID) const
	Wrap the device helper function.

void	initializeSpheres ()
	Create a helper to do sphere initialization.

void	defragment_initial_positions ()
	Sorts particle positions spatially in order to improve memory efficiency.

void	setupSphereDataStructures ()
	Setup sphere data, initialize local coords.

void	partitionBD ()
	This method figures out how big a SD is, and how many SDs are going to be necessary in order to cover the entire BD. More...

void	copyConstSphereDataToDevice ()
	Copy constant sphere data to device.

void	resetBroadphaseInformation ()
	Reset binning and broadphase info.

void	resetSphereAccelerations ()
	Reset sphere accelerations.

void	resetBCForces ()
	Reset sphere-wall forces.

void	packSphereDataPointers ()
	Collect all the sphere data into the member struct.

void	runSphereBroadphase ()
	Run the first sphere broadphase pass to get things started.

template<typename T1 , typename T2 >
T1	convertToPosSU (T2 val)
	Helper function to convert a position in UU to its SU representation while also changing data type.

void	convertBCUnits ()
	convert all BCs from UU to SU

float	get_max_vel () const
	Max velocity of all particles in system.

virtual double	get_max_K () const
	Get the maximum stiffness term in the system.

virtual void	switchToSimUnits ()
	This method defines the mass, time, length Simulation Units. More...

void	setBCOffset (const BC_type &, const BC_params_t< float, float3 > &params_UU, BC_params_t< int64_t, int64_t3 > &params_SU, double3 offset_UU)
	Set the position function of a boundary condition and account for the offset.

void	updateBCPositions ()
	Update positions of each boundary condition using prescribed functions.

Protected Attributes
double	LENGTH_SU2UU
	1 / C_L. Any length expressed in SU is a multiple of SU2UU

double	TIME_SU2UU
	1 / C_T. Any time quantity in SU is measured as a positive multiple of TIME_SU2UU

double	MASS_SU2UU
	1 / C_M. Any mass quantity is measured as a positive multiple of MASS_SU2UU.

double	FORCE_SU2UU
	1 / C_F. Any force quantity is measured as a multiple of FORCE_SU2UU.

double	TORQUE_SU2UU
	1 / C_tau. Any torque quantity is measured as a multiple of TORQUE_SU2UU.

double	VEL_SU2UU
	1 / C_v. Any velocity quantity is measured as a multiple of VEL_SU2UU.

unsigned int	psi_T
	Safety factor on simulation time.

unsigned int	psi_L
	Safety factor on space adim.

float	psi_R
	Fraction of sphere radius which gives an upper bound on the length unit.

ChGranParams *	gran_params
	Holds the sphere and big-domain-related params in unified memory.

ChGranSphereData *	sphere_data
	Holds system degrees of freedom.

GRAN_VERBOSITY	verbosity
	Allows the code to be very verbose for debugging.

bool	use_min_length_unit
	If dividing the longest box dimension into INT_MAX pieces gives better resolution than the deformation-based scaling, do that.

unsigned char	output_flags
	Bit flags indicating what fields to write out during writeFile Set with the GRAN_OUTPUT_FLAGS enum.

GRAN_OUTPUT_MODE	file_write_mode
	How to write the output files? Default is CSV.

unsigned int	nSpheres
	Number of discrete elements.

unsigned int	nSDs
	Number of subdomains.

std::vector< int, cudallocator< int > >	sphere_local_pos_X
	Store X positions relative to owner subdomain in unified memory.

std::vector< int, cudallocator< int > >	sphere_local_pos_Y
	Store Y positions relative to owner subdomain in unified memory.

std::vector< int, cudallocator< int > >	sphere_local_pos_Z
	Store Z positions relative to owner subdomain in unified memory.

std::vector< float, cudallocator< float > >	pos_X_dt
	Store X velocity in unified memory.

std::vector< float, cudallocator< float > >	pos_Y_dt
	Store Y velocity in unified memory.

std::vector< float, cudallocator< float > >	pos_Z_dt
	Store Z velocity in unified memory.

std::vector< float, cudallocator< float > >	sphere_Omega_X
	Store X angular velocity (axis and magnitude in one vector) in unified memory.

std::vector< float, cudallocator< float > >	sphere_Omega_Y
	Store Y angular velocity (axis and magnitude in one vector) in unified memory.

std::vector< float, cudallocator< float > >	sphere_Omega_Z
	Store Z angular velocity (axis and magnitude in one vector) in unified memory.

std::vector< float, cudallocator< float > >	sphere_acc_X
	Store X acceleration in unified memory.

std::vector< float, cudallocator< float > >	sphere_acc_Y
	Store Y acceleration in unified memory.

std::vector< float, cudallocator< float > >	sphere_acc_Z
	Store Z acceleration in unified memory.

std::vector< float, cudallocator< float > >	sphere_ang_acc_X
	Store X angular acceleration (axis and magnitude in one vector) in unified memory.

std::vector< float, cudallocator< float > >	sphere_ang_acc_Y
	Store Y angular acceleration (axis and magnitude in one vector) in unified memory.

std::vector< float, cudallocator< float > >	sphere_ang_acc_Z
	Store Z angular acceleration (axis and magnitude in one vector) in unified memory.

std::vector< float, cudallocator< float > >	sphere_acc_X_old
	X acceleration history used for the Chung integrator in unified memory.

std::vector< float, cudallocator< float > >	sphere_acc_Y_old
	Y acceleration history used for the Chung integrator in unified memory.

std::vector< float, cudallocator< float > >	sphere_acc_Z_old
	Z acceleration history used for the Chung integrator in unified memory.

std::vector< float, cudallocator< float > >	sphere_ang_acc_X_old
	X angular acceleration history used for the Chung integrator in unified memory.

std::vector< float, cudallocator< float > >	sphere_ang_acc_Y_old
	Y angular acceleration history used for the Chung integrator in unified memory.

std::vector< float, cudallocator< float > >	sphere_ang_acc_Z_old
	Z angular acceleration history used for the Chung integrator in unified memory.

std::vector< not_stupid_bool, cudallocator< not_stupid_bool > >	sphere_fixed
	Fixity of each sphere.

std::vector< unsigned int, cudallocator< unsigned int > >	contact_partners_map
	Set of contact partners for each sphere. Only used in frictional simulations.

std::vector< not_stupid_bool, cudallocator< not_stupid_bool > >	contact_active_map
	Whether the frictional contact at an index is active.

std::vector< float3, cudallocator< float3 > >	contact_history_map
	Tracks the tangential history vector for a given contact pair. Only used in multistep friction.

std::vector< float3, cudallocator< float3 > >	normal_contact_force
	Tracks the normal contact force for a given contact pair.

std::vector< float3, cudallocator< float3 > >	tangential_friction_force
	Tracks the tangential contact force for a given contact pair.

std::vector< float3, cudallocator< float3 > >	rolling_friction_torque
	Tracks the rolling resistance for a given contact pair.

float	X_accGrav
	X gravity in user units.

float	Y_accGrav
	Y gravity in user units.

float	Z_accGrav
	Z gravity in user units.

std::vector< unsigned int, cudallocator< unsigned int > >	SD_NumSpheresTouching
	Entry "i" says how many spheres touch subdomain i.

std::vector< unsigned int, cudallocator< unsigned int > >	SD_SphereCompositeOffsets

std::vector< unsigned int, cudallocator< unsigned int > >	spheres_in_SD_composite
	Array containing the IDs of the spheres stored in the SDs associated with the box.

std::vector< unsigned int, cudallocator< unsigned int > >	sphere_owner_SDs
	List of owner subdomains for each sphere.

float	stepSize_UU
	User provided timestep in UU.

float	stepSize_SU
	SU (adimensional) value of time step.

GRAN_TIME_INTEGRATOR	time_integrator
	how is the system integrated through time?

float	elapsedSimTime
	Total time elapsed since beginning of simulation.

double	K_n_s2s_UU
	Normal stiffness for sphere-to-sphere contact (Hertzian spring constant)

double	K_n_s2w_UU
	Normal stiffness for sphere-to-wall contact (Hertzian spring constant)

double	Gamma_n_s2s_UU
	Normal damping for sphere-to-sphere.

double	Gamma_n_s2w_UU
	Normal damping for sphere-to-wall.

double	K_t_s2s_UU
	Tangential stiffness for sphere-to-sphere (Hertzian spring constant.

double	K_t_s2w_UU
	Tangential stiffness for sphere-to-wall (Hertzian spring constant.

double	Gamma_t_s2s_UU
	Tangential damping for sphere-to-sphere.

double	Gamma_t_s2w_UU
	Tangential damping for sphere-to-wall.

double	rolling_coeff_s2s_UU
	Rolling friction coefficient for sphere-to-sphere.

double	rolling_coeff_s2w_UU
	Rolling friction coefficient for sphere-to-wall Units and use are dependent on the rolling friction model used.

double	spinning_coeff_s2s_UU
	Spinning friction coefficient for sphere-to-sphere.

double	spinning_coeff_s2w_UU
	Spinning friction coefficient for sphere-to-wall Units and use are dependent on the spinning friction model used.

float	cohesion_over_gravity
	Store the ratio of the acceleration due to cohesion vs the acceleration due to gravity, makes simple API.

float	adhesion_s2w_over_gravity
	Store the ratio of the acceleration due to adhesion vs the acceleration due to gravity.

int64_t3	BD_rest_frame_SU
	The reference point for UU to SU local coordinates.

std::vector< BC_type, cudallocator< BC_type > >	BC_type_list
	List of generalized boundary conditions that constrain sphere motion.

std::vector< BC_params_t< int64_t, int64_t3 >, cudallocator< BC_params_t< int64_t, int64_t3 > > >	BC_params_list_SU
	Sim-unit (adimensional) details of boundary conditions.

std::vector< BC_params_t< float, float3 >, cudallocator< BC_params_t< float, float3 > > >	BC_params_list_UU
	User-unit (dimensional) details of boundary conditions.

std::vector< GranPositionFunction >	BC_offset_function_list
	Offset motions functions for boundary conditions – used for moving walls, wavetanks, etc.

const float	sphere_radius_UU
	User defined radius of the sphere.

const float	sphere_density_UU
	User defined density of the sphere.

const float	box_size_X
	X-length of the big domain; defines the global X axis located at the CM of the box.

const float	box_size_Y
	Y-length of the big domain; defines the global Y axis located at the CM of the box.

const float	box_size_Z
	Z-length of the big domain; defines the global Z axis located at the CM of the box.

std::vector< float3 >	user_sphere_positions
	User-provided sphere positions in UU.

std::vector< float3 >	user_sphere_vel
	User-provided sphere velocities in UU.

std::vector< float3 >	user_sphere_ang_vel

std::vector< bool >	user_sphere_fixed
	User-provided sphere fixity as bools.

bool	BD_is_fixed = true
	Allow the user to set the big domain to be fixed, ignoring any given position functions.

Member Function Documentation

◆ partitionBD()

void chrono::granular::ChSystemGranularSMC::partitionBD ( )

protected

This method figures out how big a SD is, and how many SDs are going to be necessary in order to cover the entire BD.

Nomenclature: BD: Big domain, SD: Sub-domain.

◆ set_friction_mode()

void chrono::granular::ChSystemGranularSMC::set_friction_mode ( GRAN_FRICTION_MODE new_mode )

inline

Set friction formulation.

The frictionless setting uses a streamlined solver and avoids storing any physics information associated with friction

◆ set_rolling_mode()

void chrono::granular::ChSystemGranularSMC::set_rolling_mode ( GRAN_ROLLING_MODE new_mode )

inline

Set rolling resistence formulation.

NOTE: This requires friction to be active, otherwise this setting will be ignored

◆ switchToSimUnits()

void chrono::granular::ChSystemGranularSMC::switchToSimUnits ( )

protectedvirtual

This method defines the mass, time, length Simulation Units.

It also sets several other constants that enter the scaling of various physical quantities set by the user.

SU values for normal stiffnesses for S2S and S2W

The documentation for this class was generated from the following files:

/builds/uwsbel/chrono/src/chrono_granular/physics/ChGranular.h
/builds/uwsbel/chrono/src/chrono_granular/physics/ChGranular.cpp

Description

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Member Function Documentation

◆ partitionBD()

◆ set_friction_mode()

◆ set_rolling_mode()

◆ switchToSimUnits()