Computes normal forces for a Herztian visco-elastic interaction. More...

#include <HertzianViscoelasticInteraction.h>

Inheritance diagram for HertzianViscoelasticInteraction:

Public Types
typedef HertzianViscoelasticNormalSpecies	SpeciesType
	An alias for HertzianViscoelasticNormalSpecies. More...

Public Member Functions
	HertzianViscoelasticInteraction (BaseInteractable P, BaseInteractable I, unsigned timeStamp)
	Constructor. More...

	HertzianViscoelasticInteraction ()

	HertzianViscoelasticInteraction (const HertzianViscoelasticInteraction &p)
	Copy constructor. More...

	~HertzianViscoelasticInteraction () override
	Destructor. More...

void	computeNormalForce ()
	Computes the amount of normal force due to an Hertzian visco-elastic interaction. More...

	HertzianViscoelasticInteraction (const BaseInteraction &p)

void	read (std::istream &is) override
	Interaction read function, which accepts an std::istream as input. More...

void	write (std::ostream &os) const override
	Interaction write function, which accepts an std::ostream as input. More...

std::string	getBaseName () const
	Returns the name of the interaction. More...

Mdouble	getElasticEnergy () const override
	Computes and returns the amount of elastic energy stored in the spring. More...

const HertzianViscoelasticNormalSpecies *	getSpecies () const
	Returns a const pointer of type HerztianViscoelasticNormalSpecies (static-cast). More...

Mdouble	getElasticEnergyAtEquilibrium (Mdouble adhesiveForce) const override

Public Member Functions inherited from BaseInteraction
	BaseInteraction (BaseInteractable P, BaseInteractable I, unsigned timeStamp)
	A constructor takes the BaseInteractable objects which are interacting (come into contact) and time the interaction starts. More...

	BaseInteraction ()

	BaseInteraction (const BaseInteraction &p)
	Copy constructor. More...

	~BaseInteraction () override
	The destructor. It removes this interactions from the objects that were interacting, and writes the time to a file when needed. More...

virtual void	actionsOnErase ()
	If an interaction needs to do something before it gets erased, add it here. E.g. Liquid bridges rupture at the end of their lifetime, and the liquid bridge volume has to be redistributed. The reason this action is not done in the destructor is that this action should not be taken when erasing ghost interactions. More...

virtual void	computeForce ()
	Virtual function that contains the force law between the two objects interacting. More...

void	writeToFStat (std::ostream &os, Mdouble time) const
	Writes forces data to the FStat file. More...

std::string	getName () const override
	Virtual function which allows interactions to be named. More...

void	setDistance (Mdouble distance)
	Sets the interaction distance between the two interacting objects. More...

void	setNormal (Vec3D normal)
	Sets the normal vector between the two interacting objects. More...

void	setOverlap (Mdouble overlap)
	Set the overlap between the two interacting object. More...

void	setContactPoint (Vec3D contactPoint)
	Set the location of the contact point between the two interacting objects. More...

void	setTimeStamp (unsigned timeStamp)
	Updates the time step of the interacting. Note, time steps used to find completed interactions. More...

void	setSpecies (const BaseSpecies *species)
	Set the Species of the interaction; note this can either be a Species or MixedSpecies. More...

void	setP (BaseInteractable *P)
	Sets the first object involved in the interaction (normally a particle). More...

void	setI (BaseInteractable *I)
	Sets the second object involved in the interaction (often particle or wall). More...

void	importP (BaseInteractable *P)
	Sets the first object involved in the interaction (normally a particle). More...

void	importI (BaseInteractable *I)
	Sets the second object involved in the interaction (often particle or wall). More...

Vec3D	getIP () const

Vec3D	getIC () const

Vec3D	getCP () const

void	setLagrangeMultiplier (Mdouble multiplier)

Mdouble	getLagrangeMultiplier ()

void	setHandler (InteractionHandler *handler)
	Sets the pointer to the interaction hander which is storing this interaction. More...

InteractionHandler *	getHandler () const
	Gets a point to the interaction handlers to which this interaction belongs. More...

const Vec3D &	getForce () const
	Gets the current force (vector) between the two interacting objects. More...

const Vec3D &	getTorque () const
	Gets the current torque (vector) between the two interacting objects. More...

const Vec3D &	getNormal () const
	Gets the normal vector between the two interacting objects. More...

const Vec3D &	getContactPoint () const
	Gets constant reference to contact point (vector). More...

Mdouble	getOverlap () const
	Returns a Mdouble with the current overlap between the two interacting objects. More...

Mdouble	getOverlapVolume () const
	Returns the overlap volume between two interacting objects. More...

Mdouble	getContactRadius () const
	Returns a Mdouble with the current contact between the two interacting objects. More...

void	removeFromHandler ()
	Removes this interaction from its interaction hander. More...

void	copySwitchPointer (const BaseInteractable original, BaseInteractable ghost) const
	This copies the interactions of the original particle and replaces the original with the ghost copy. More...

void	gatherContactStatistics ()

BaseInteractable *	getP ()
	Returns a pointer to first object involved in the interaction (normally a particle). More...

BaseInteractable *	getI ()
	Returns a pointer to the second object involved in the interaction (often a wall or a particle). More...

const BaseInteractable *	getP () const
	Returns a constant pointer to the first object involved in the interaction. More...

const BaseInteractable *	getI () const
	Returns a constant pointer to the second object involved in the interaction. More...

Mdouble	getTimeStamp () const
	Returns an Mdouble which is the time stamp of the interaction. More...

virtual void	integrate (Mdouble timeStep)
	integrates variables of the interaction which need to be integrate e.g. the tangential overlap. More...

virtual Mdouble	getTangentialOverlap () const
	get the length of the current tangential overlap More...

Mdouble	getDistance () const
	Returns an Mdouble which is the norm (length) of distance vector. More...

const Vec3D &	getRelativeVelocity () const
	Returns a constant reference to a vector of relative velocity. More...

Mdouble	getNormalRelativeVelocity () const
	Returns a double which is the norm (length) of the relative velocity vector. More...

Mdouble	getAbsoluteNormalForce () const
	Returns the absolute value of the norm (length) of the Normal force vector. More...

virtual BaseInteraction *	copy () const =0
	Makes a copy of the interaction and returns a pointer to the copy. More...

void	setFStatData (std::fstream &fstat, BaseParticle P, BaseWall I)

void	setFStatData (std::fstream &fstat, BaseParticle P, BaseParticle I)

unsigned int	getMultiContactIdentifier () const

void	setMultiContactIdentifier (unsigned int multiContactIdentifier_)

virtual void	rotateHistory (Matrix3D &rotationMatrix)
	When periodic particles are used, some interactions need certain history properties rotated (e.g. tangential springs). This is the function for that. More...

virtual void	actionsAfterTimeStep ()

virtual unsigned	getNumberOfFieldsVTK () const

virtual std::string	getTypeVTK (unsigned i) const

virtual std::string	getNameVTK (unsigned i) const

virtual std::vector< Mdouble >	getFieldVTK (unsigned i) const

void	addForce (Vec3D force)
	add an force increment to the total force. More...

void	addTorque (Vec3D torque)
	add a torque increment to the total torque. More...

void	setForce (Vec3D force)
	set total force (this is used by the normal force, tangential forces are added use addForce) More...

void	setTorque (Vec3D torque)
	set the total force (this is used by the normal force, tangential torques are added use addTorque) More...

const BaseSpecies *	getBaseSpecies () const
	Return a constant point to BaseSpecies of the interaction. More...

virtual void	createMPIType ()

virtual void *	createMPIInteractionDataArray (unsigned int numberOfInteractions) const

virtual void	deleteMPIInteractionDataArray (void *dataArray)

virtual void	getMPIInteraction (void *historyDataArray, unsigned int index) const
	copies the history interactions into the data array More...

virtual void	getInteractionDetails (void *interactionDataArray, unsigned int index, unsigned int &identificationP, unsigned int &identificationI, bool &isWallInteraction, unsigned &timeStamp)

virtual void	setMPIInteraction (void *interactionDataArray, unsigned int index, bool resetPointers)

void	setBasicMPIInteractionValues (int P, int I, unsigned timeStamp, Vec3D force, Vec3D torque, bool isWallInteraction, bool resetPointers)

void	setIdentificationP (unsigned int identification)

void	setIdentificationI (int identification)

void	setWallInteraction (bool flag)

unsigned int	getIdentificationP ()

int	getIdentificationI ()

bool	isWallInteraction ()

virtual bool	isBonded () const

Public Member Functions inherited from BaseObject
	BaseObject ()=default
	Default constructor. More...

	BaseObject (const BaseObject &p)=default
	Copy constructor, copies all the objects BaseObject contains. More...

virtual	~BaseObject ()=default
	virtual destructor More...

virtual void	moveInHandler (unsigned int index)
	Except that it is virtual, it does the same thing as setIndex() does. More...

void	setIndex (unsigned int index)
	Allows one to assign an index to an object in the handler/container. More...

void	setId (unsigned long id)
	Assigns a unique identifier to each object in the handler (container) which remains constant even after the object is deleted from the container/handler. More...

unsigned int	getIndex () const
	Returns the index of the object in the handler. More...

unsigned int	getId () const
	Returns the unique identifier of any particular object. More...

void	setGroupId (unsigned groupId)

unsigned	getGroupId () const

Additional Inherited Members
Protected Member Functions inherited from BaseInteraction
virtual const Vec3D	getTangentialForce () const

Mdouble	getEffectiveRadius () const
	Returns a Mdouble to the effective radius of the interaction. (Not corrected for the overlap) More...

Mdouble	getEffectiveMass () const
	Returns a Mdouble to the effective radius of the interaction. (Not corrected for the overlap) More...

void	setRelativeVelocity (Vec3D relativeVelocity)
	set the relative velocity of the current of the interactions. More...

void	setNormalRelativeVelocity (Mdouble normalRelativeVelocit)
	set the normal component of the relative velocity. More...

void	setAbsoluteNormalForce (Mdouble absoluteNormalForce)
	the absolute values of the norm (length) of the normal force More...

virtual void	reverseHistory ()
	When periodic particles some interaction need certain history properties reversing. This is the function for that. More...

void	writeInteraction (std::ostream &os, bool created) const
	Writes information about a interaction to the interaction file. More...

Detailed Description

Computes normal forces for a Herztian visco-elastic interaction.

Member Typedef Documentation

◆ SpeciesType

typedef HertzianViscoelasticNormalSpecies HertzianViscoelasticInteraction::SpeciesType

An alias for HertzianViscoelasticNormalSpecies.

Constructor & Destructor Documentation

◆ HertzianViscoelasticInteraction() [1/4]

HertzianViscoelasticInteraction::HertzianViscoelasticInteraction	(	BaseInteractable *	P,
		BaseInteractable *	I,
		unsigned	timeStamp
	)

Constructor.

Parameters

[in]	P
[in]	I
[in]	timeStamp

         : BaseInteraction(P, I, timeStamp)
 {
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"HertzianViscoelasticInteraction::HertzianViscoelasticInteraction() finished"<<std::endl;
 #endif
 }

◆ HertzianViscoelasticInteraction() [2/4]

HertzianViscoelasticInteraction::HertzianViscoelasticInteraction ( )

default

◆ HertzianViscoelasticInteraction() [3/4]

HertzianViscoelasticInteraction::HertzianViscoelasticInteraction ( const HertzianViscoelasticInteraction & p )

Copy constructor.

Parameters

[in] p

         : BaseInteraction(p)
 {
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"HertzianViscoelasticInteraction::HertzianViscoelasticInteraction(const HertzianViscoelasticInteraction& p) finished"<<std::endl;
 #endif
 }

◆ ~HertzianViscoelasticInteraction()

HertzianViscoelasticInteraction::~HertzianViscoelasticInteraction ( )

override

Destructor.

 {
 #ifdef DEBUG_DESTRUCTOR
     std::cout<<"HertzianViscoelasticInteraction::~HertzianViscoelasticInteraction() finished"<<std::endl;
 #endif
 }

◆ HertzianViscoelasticInteraction() [4/4]

HertzianViscoelasticInteraction::HertzianViscoelasticInteraction ( const BaseInteraction & p )

inlineexplicit

                                                                        : BaseInteraction(p)
     {
         
     }

Member Function Documentation

◆ computeNormalForce()

void HertzianViscoelasticInteraction::computeNormalForce ( )

Computes the amount of normal force due to an Hertzian visco-elastic interaction.

The contact model is based on the description given in http://people.ds.cam.ac.uk/jae1001/CUS/research/pfizer/Antypov_Elliott_EPL_2011.pdf (which is the same as in Yade https://answers.launchpad.net/yade/+question/235934) kn = 4/3 E* sqrt(R/2 delta) = sqrt(2)/3 kn fn = kn delta + gamma sqrt(m/2 kn) vn =

Note, the constants are slightly different in the C Thornton model, otherwise it's the same: www.cfd.com.au/cfd_conf12/PDFs/175CUM.pdf

Todo:: check for superquadrics

 {
     // This function is called for all particles within interactionRadius distance.
     
     // This has to be outside the loop because it is needed for the other forces
     // Compute the relative velocity vector of particle P w.r.t. I
     setRelativeVelocity(
             getP()->getVelocityAtContact(getContactPoint()) - getI()->getVelocityAtContact(getContactPoint()));
     // Compute the projection of vrel onto the normal (can be negative)
     setNormalRelativeVelocity(Vec3D::dot(getRelativeVelocity(), getNormal()));
     
     if (getOverlap() > 0) //if contact forces
     {
         const HertzianViscoelasticNormalSpecies* species = getSpecies();
         
         Mdouble stiffness = 4. / 3. * species->getEffectiveElasticModulus() * std::sqrt(getEffectiveRadius() * getOverlap());
         
         //calculating the current normal force
         //dissipation is computed such that the restitution is constant
         Mdouble dissipationCoefficient = species->getDissipation() * sqrt(getEffectiveMass() * stiffness);
         Mdouble normalForce = stiffness * getOverlap() - dissipationCoefficient * getNormalRelativeVelocity();
         
         //setting the normal force parameter in the base interaction class so that it can be accessed
         //by other classes...
         setAbsoluteNormalForce(std::abs(normalForce)); //used for further force calculations;
         setForce(getNormal() * normalForce);
         setTorque(Vec3D(0.0, 0.0, 0.0));
     }
     else
     {
         setAbsoluteNormalForce(0.0);
         setForce(Vec3D(0.0, 0.0, 0.0));
         setTorque(Vec3D(0.0, 0.0, 0.0));
     }
 }

◆ getBaseName()

std::string HertzianViscoelasticInteraction::getBaseName ( ) const

Returns the name of the interaction.

Returns: std::string

 {
     return "HertzianViscoelastic";
 }

◆ getElasticEnergy()

Mdouble HertzianViscoelasticInteraction::getElasticEnergy ( ) const

overridevirtual

Computes and returns the amount of elastic energy stored in the spring.

kn = 4/3 E* sqrt(R/2 delta) fn = kn delta -> E = int fn ddelta = 2/5 4/3 E sqrt(R/2 delta) delta^2

Reimplemented from BaseInteraction.

 {
     if (getOverlap() > 0)
     {
         return 8. / 15. * getSpecies()->getEffectiveElasticModulus() * std::sqrt(getEffectiveRadius() * getOverlap()) *
                mathsFunc::square(getOverlap());
     }
     else
     {
         return 0.0;
     }
 }

References BaseInteraction::getEffectiveRadius(), BaseInteraction::getOverlap(), getSpecies(), and mathsFunc::square().

◆ getElasticEnergyAtEquilibrium()

Mdouble HertzianViscoelasticInteraction::getElasticEnergyAtEquilibrium ( Mdouble adhesiveForce ) const

overridevirtual

Computes elastic-adhesive energy at zero overlap, assuming the energy is zero at the equilibrium point mod = 4/3 E* sqrt(R/2) fn = mod delta^3/2 - fadh -> E = int_deltaEq^0 fn ddelta = [2/5 mod delta^5/2 - fadh * delta]_deltaEq^0 = [2/5 fn delta - 3/5 fadh delta]_deltaEq^0 = 3/5 fadh deltaEq

Todo:: TW consider renaming to getElasticAdhesiveEnergy or getElasticAdhesiveEnergyRelativeToEquilibrium

Reimplemented from BaseInteraction.

 {
     const HertzianViscoelasticNormalSpecies* species = getSpecies();
     const Mdouble modulus = 4. / 3. * species->getEffectiveElasticModulus() * std::sqrt(getEffectiveRadius());
     const Mdouble equilibriumOverlap = std::cbrt(mathsFunc::square(adhesiveForce / modulus));
     return 0.6 * adhesiveForce * equilibriumOverlap;//why not 0.4?
 }

References BaseInteraction::getEffectiveRadius(), getSpecies(), and mathsFunc::square().

◆ getSpecies()

const HertzianViscoelasticNormalSpecies * HertzianViscoelasticInteraction::getSpecies ( ) const

Returns a const pointer of type HerztianViscoelasticNormalSpecies (static-cast).

Returns: const HertzianViscoelasticNormalSpecies*

 {
     return static_cast<const HertzianViscoelasticNormalSpecies*>(getBaseSpecies()->getNormalForce());
 }

References BaseInteraction::getBaseSpecies(), and BaseSpecies::getNormalForce().

Referenced by computeNormalForce(), getElasticEnergy(), and getElasticEnergyAtEquilibrium().

◆ read()

void HertzianViscoelasticInteraction::read ( std::istream & is )

overridevirtual

Interaction read function, which accepts an std::istream as input.

Parameters

[in,out] is

Reimplemented from BaseInteraction.

 {
     BaseInteraction::read(is);
 }

References BaseInteraction::read().

Referenced by HertzianBSHPViscoelasticInteraction::read().

◆ write()

void HertzianViscoelasticInteraction::write ( std::ostream & os ) const

overridevirtual

Interaction write function, which accepts an std::ostream as input.

Parameters

[in,out] os

Reimplemented from BaseInteraction.

 {
     BaseInteraction::write(os);
 }

References BaseInteraction::write().

Referenced by HertzianBSHPViscoelasticInteraction::write().

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

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ SpeciesType

Constructor & Destructor Documentation

◆ HertzianViscoelasticInteraction() [1/4]

◆ HertzianViscoelasticInteraction() [2/4]

◆ HertzianViscoelasticInteraction() [3/4]

◆ ~HertzianViscoelasticInteraction()

◆ HertzianViscoelasticInteraction() [4/4]

Member Function Documentation

◆ computeNormalForce()

◆ getBaseName()

◆ getElasticEnergy()

◆ getElasticEnergyAtEquilibrium()

◆ getSpecies()

◆ read()

◆ write()