LinearViscoelasticNormalSpecies contains the parameters used to describe a linear elastic-dissipative normal force. More...

#include <LinearViscoelasticNormalSpecies.h>

Inheritance diagram for LinearViscoelasticNormalSpecies:

Public Types
typedef LinearViscoelasticInteraction	InteractionType
	The correct Interaction type for this FrictionForceSpecies. More...

Public Member Functions
	LinearViscoelasticNormalSpecies ()
	The default constructor. More...

	LinearViscoelasticNormalSpecies (const LinearViscoelasticNormalSpecies &p)
	The default copy constructor. More...

virtual	~LinearViscoelasticNormalSpecies ()
	The default destructor. More...

void	read (std::istream &is)
	Reads the species properties from an input stream. More...

void	write (std::ostream &os) const
	Writes the species properties to an output stream. More...

std::string	getBaseName () const
	Used in Species::getName to obtain a unique name for each Species. More...

Mdouble	getMaximumVelocity (Mdouble radius, Mdouble mass) const
	Calculates the maximum velocity allowed for a collision of two copies of P (for higher velocities particles could pass through each other) More...

void	setStiffnessAndRestitutionCoefficient (Mdouble k_, Mdouble eps, Mdouble mass)
	Sets k, disp such that it matches a given tc and eps for a collision of two copies of P. More...

void	setCollisionTimeAndRestitutionCoefficient (Mdouble tc, Mdouble eps, Mdouble mass)
	Sets k, disp such that it matches a given tc and eps for a collision of two copies of equal mass m. More...

void	setCollisionTimeAndRestitutionCoefficient (Mdouble collisionTime, Mdouble restitutionCoefficient, Mdouble mass1, Mdouble mass2)
	Set k, disp such that is matches a given tc and eps for a collision of two different masses. More...

Mdouble	getCollisionTime (Mdouble mass) const
	Calculates collision time for two copies of a particle of given disp, k, mass. More...

Mdouble	getRestitutionCoefficient (Mdouble mass) const
	Calculates restitution coefficient for two copies of given disp, k, mass. More...

void	mix (LinearViscoelasticNormalSpecies const SBase, LinearViscoelasticNormalSpecies const TBase)
	creates default values for mixed species More...

void	setStiffness (Mdouble new_k)
	Allows the spring constant to be changed. More...

Mdouble	getStiffness () const
	Allows the spring constant to be accessed. More...

void	setDissipation (Mdouble dissipation)
	Allows the normal dissipation to be changed. More...

Mdouble	getDissipation () const
	Allows the normal dissipation to be accessed. More...

MERCURY_DEPRECATED void	setStiffnessAndDissipation (helpers::KAndDisp new_)
	Allows the spring and dissipation constants to be changed simultaneously. More...

Public Member Functions inherited from BaseSpecies
	BaseSpecies ()
	The default constructor. More...

	BaseSpecies (const BaseSpecies &p)
	The copy constructor. More...

virtual	~BaseSpecies ()
	The default destructor. More...

virtual BaseSpecies *	copy () const =0
	Creates a deep copy of the object from which it is called. More...

void	setHandler (SpeciesHandler *handler)
	Sets the pointer to the handler to which this species belongs. More...

SpeciesHandler *	getHandler () const
	Returns the pointer to the handler to which this species belongs. More...

Mdouble	average (Mdouble a, Mdouble b)
	defines the average of two variables by the harmonic mean. More...

virtual void	mixAll (BaseSpecies const S, BaseSpecies const T)=0
	creates default values for mixed species More...

virtual Mdouble	getInteractionDistance () const =0
	returns the largest separation distance at which adhesive short-range forces can occur. More...

virtual bool	getUseAngularDOFs () const =0
	Returns true if torques (i.e. angular degrees of freedom) have to be calculated. More...

virtual BaseInteraction *	getNewInteraction (BaseInteractable P, BaseInteractable I, Mdouble timeStamp) const =0
	returns new Interaction object. More...

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

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

virtual	~BaseObject ()
	virtual destructor More...

virtual std::string	getName () const =0
	A purely virtual function. More...

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

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

void	setId (const unsigned int 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...

Private Attributes
Mdouble	stiffness_
	(normal) spring constant More...

Mdouble	dissipation_
	(normal) viscosity More...

Detailed Description

LinearViscoelasticNormalSpecies contains the parameters used to describe a linear elastic-dissipative normal force.

See LinearViscoelasticNormalInteraction::computeForce for a description of the force law.

Definition at line 36 of file LinearViscoelasticNormalSpecies.h.

Member Typedef Documentation

typedef LinearViscoelasticInteraction LinearViscoelasticNormalSpecies::InteractionType

The correct Interaction type for this FrictionForceSpecies.

Definition at line 40 of file LinearViscoelasticNormalSpecies.h.

Constructor & Destructor Documentation

LinearViscoelasticNormalSpecies::LinearViscoelasticNormalSpecies ( )

The default constructor.

Definition at line 35 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, and stiffness_.

 {
     stiffness_ = 0;
     dissipation_ = 0;
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"LinearViscoelasticNormalSpecies::LinearViscoelasticNormalSpecies() finished"<<std::endl;
 #endif
 }

LinearViscoelasticNormalSpecies::LinearViscoelasticNormalSpecies ( const LinearViscoelasticNormalSpecies & p )

The default copy constructor.

Parameters

[in] the species that is copied

Definition at line 47 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, and stiffness_.

 {
     stiffness_ = p.stiffness_;
     dissipation_ = p.dissipation_;
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"LinearViscoelasticNormalSpecies::LinearViscoelasticNormalSpecies(const LinearViscoelasticNormalSpecies &p) finished"<<std::endl;
 #endif
 }

LinearViscoelasticNormalSpecies::~LinearViscoelasticNormalSpecies ( )

virtual

The default destructor.

Definition at line 56 of file LinearViscoelasticNormalSpecies.cc.

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

Member Function Documentation

std::string LinearViscoelasticNormalSpecies::getBaseName ( ) const

Used in Species::getName to obtain a unique name for each Species.

Returns: a string containing the name of the species (minus the word "Species")

Definition at line 85 of file LinearViscoelasticNormalSpecies.cc.

 {
     return "LinearViscoelastic";
 }

Mdouble LinearViscoelasticNormalSpecies::getCollisionTime ( Mdouble mass ) const

Calculates collision time for two copies of a particle of given disp, k, mass.

Definition at line 136 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, constants::pi, mathsFunc::square(), and stiffness_.

Referenced by getRestitutionCoefficient().

 {
     if (mass <= 0)
     {
         std::cerr << "Warning in getCollisionTime(" << mass << ") mass is not set or has an unexpected value, (getCollisionTime(" << mass << "))" << std::endl;
     }
     if (stiffness_ <= 0)
     {
         std::cerr << "Warning in getCollisionTime(" << mass << ") stiffness=" << stiffness_ << " is not set or has an unexpected value, (getCollisionTime(" << mass << "), with stiffness=" << stiffness_ << ")" << std::endl;
     }
     if (dissipation_ < 0)
     {
         std::cerr << "Warning in getCollisionTime(" << mass << ") dissipation=" << dissipation_ << " is not set or has an unexpected value, (getCollisionTime(" << mass << "), with dissipation=" << dissipation_ << ")" << std::endl;
     }
     Mdouble tosqrt = stiffness_ / (.5 * mass) - mathsFunc::square(dissipation_ / mass);
     if (tosqrt <= 0)
     {
         std::cerr << "Warning in getCollisionTime(" << mass << ") values for mass, stiffness and dissipation would lead to an overdamped system, (getCollisionTime(" << mass << "), with stiffness=" << stiffness_ << " and dissipation=" << dissipation_ << ")" << std::endl;
     }
     return constants::pi / std::sqrt(tosqrt);
 }

Mdouble LinearViscoelasticNormalSpecies::getDissipation ( ) const

Allows the normal dissipation to be accessed.

Definition at line 130 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_.

Referenced by LinearViscoelasticInteraction::computeNormalForce(), mix(), and setCollisionTimeAndRestitutionCoefficient().

 {
     return dissipation_;
 }

Mdouble LinearViscoelasticNormalSpecies::getMaximumVelocity	(	Mdouble	radius,
		Mdouble	mass
	)		const

Calculates the maximum velocity allowed for a collision of two copies of P (for higher velocities particles could pass through each other)

Definition at line 165 of file LinearViscoelasticNormalSpecies.cc.

References stiffness_.

 {
     return radius * std::sqrt(stiffness_ / (.5 * mass));
 }

Mdouble LinearViscoelasticNormalSpecies::getRestitutionCoefficient ( Mdouble mass ) const

Calculates restitution coefficient for two copies of given disp, k, mass.

Definition at line 159 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, mathsFunc::exp(), and getCollisionTime().

 {
     return std::exp(-dissipation_ / mass * getCollisionTime(mass));
 }

Mdouble LinearViscoelasticNormalSpecies::getStiffness ( ) const

Allows the spring constant to be accessed.

Definition at line 103 of file LinearViscoelasticNormalSpecies.cc.

References stiffness_.

Referenced by LinearViscoelasticInteraction::computeNormalForce(), LinearViscoelasticInteraction::getElasticEnergy(), LinearViscoelasticInteraction::getElasticEnergyAtEquilibrium(), mix(), SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficient(), SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficientNoDispt(), and setCollisionTimeAndRestitutionCoefficient().

 {
     return stiffness_;
 }

void LinearViscoelasticNormalSpecies::mix	(	LinearViscoelasticNormalSpecies *const	S,
		LinearViscoelasticNormalSpecies *const	T
	)

creates default values for mixed species

For all parameters we assume that the harmonic mean of the parameters of the original two species is a sensible default.

Parameters

[in] S,T the two species whose properties are mixed to create the new species

Definition at line 223 of file LinearViscoelasticNormalSpecies.cc.

References BaseSpecies::average(), dissipation_, getDissipation(), getStiffness(), and stiffness_.

 {
     stiffness_ = average(S->getStiffness(), T->getStiffness());
     dissipation_ = average(S->getDissipation(), T->getDissipation());
 }

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

virtual

Reads the species properties from an input stream.

Parameters

[in] input stream (typically the restart file)

Implements BaseObject.

Definition at line 75 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, and stiffness_.

 {
     std::string dummy;
     is >> dummy >> stiffness_
             >> dummy >> dissipation_;
 }

void LinearViscoelasticNormalSpecies::setCollisionTimeAndRestitutionCoefficient	(	Mdouble	tc,
		Mdouble	eps,
		Mdouble	mass
	)

Sets k, disp such that it matches a given tc and eps for a collision of two copies of equal mass m.

Sets k, disp such that it matches a given tc and eps for a collision of two copies of equal mass m

Parameters

[in]	tc	collision time
[in]	eps	restitution coefficient
[in]	mass	effective particle mass, $\frac{2}{1/m1+1/m2}$

Definition at line 192 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, getDissipation(), getStiffness(), INFO, mathsFunc::log(), logger, constants::pi, mathsFunc::square(), and stiffness_.

Referenced by SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficient(), SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficientNoDispt(), and setCollisionTimeAndRestitutionCoefficient().

 {
     if (eps==0.0) {
         stiffness_ = .5 * mass * mathsFunc::square(constants::pi / tc);
         dissipation_ = std::sqrt(2.0 * mass * stiffness_);
     } else {
         dissipation_ = -mass / tc * mathsFunc::log(eps);
         stiffness_ = .5 * mass * (mathsFunc::square(constants::pi / tc) 
             + mathsFunc::square(dissipation_ / mass));
     }
     logger(INFO,"setCollisionTimeAndRestitutionCoefficient: set stiffness to % and dissipation to % to obtain a collision time of % and a restitution coefficient of % for two particles of mass %",
            getStiffness(),getDissipation(),tc,eps,mass);
 }

void LinearViscoelasticNormalSpecies::setCollisionTimeAndRestitutionCoefficient	(	Mdouble	collisionTime,
		Mdouble	restitutionCoefficient,
		Mdouble	mass1,
		Mdouble	mass2
	)

Set k, disp such that is matches a given tc and eps for a collision of two different masses.

Recall the resitution constant is a function of k, disp and the mass of each particle in the collision See also setCollisionTimeAndRestitutionCoefficient(Mdouble tc, Mdouble eps, Mdouble mass)

Set k, disp such that is matches a given tc and eps for a collision of two different masses. Recall the resitution constant is a function of k, disp and the mass of each particle in the collision See also setCollisionTimeAndRestitutionCoefficient(Mdouble tc, Mdouble eps, Mdouble mass)

Parameters

[in] collision time

Definition at line 212 of file LinearViscoelasticNormalSpecies.cc.

References setCollisionTimeAndRestitutionCoefficient().

 {
     Mdouble reduced_mass = mass1 * mass2 / (mass1 + mass2);
     setCollisionTimeAndRestitutionCoefficient(collisionTime, restitutionCoefficient, 2.0 * reduced_mass);
 }

void LinearViscoelasticNormalSpecies::setDissipation ( Mdouble dissipation )

Allows the normal dissipation to be changed.

Definition at line 116 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_.

Referenced by setStiffnessAndDissipation().

 {
     if (dissipation >= 0)
     {
         dissipation_ = dissipation;
     }
     else
     {
         std::cerr << "Error in setDissipation(" << dissipation << ")" << std::endl;
         exit(-1);
     }
 }

void LinearViscoelasticNormalSpecies::setStiffness ( Mdouble new_k )

Allows the spring constant to be changed.

Definition at line 91 of file LinearViscoelasticNormalSpecies.cc.

References stiffness_.

Referenced by setStiffnessAndDissipation().

 {
     if (new_k >= 0)
         stiffness_ = new_k;
     else
     {
         std::cerr << "Error in set_k" << std::endl;
         exit(-1);
     }
 }

void LinearViscoelasticNormalSpecies::setStiffnessAndDissipation ( helpers::KAndDisp new_ )

Allows the spring and dissipation constants to be changed simultaneously.

Definition at line 109 of file LinearViscoelasticNormalSpecies.cc.

References helpers::KAndDisp::disp, helpers::KAndDisp::k, setDissipation(), and setStiffness().

 {
     setStiffness(new_.k);
     setDissipation(new_.disp);
 }

void LinearViscoelasticNormalSpecies::setStiffnessAndRestitutionCoefficient	(	Mdouble	stiffness,
		Mdouble	eps,
		Mdouble	mass
	)

Sets k, disp such that it matches a given tc and eps for a collision of two copies of P.

Sets k, disp such that it matches a given tc and eps for a collision of two copies of P

Parameters

[in]	stiffness	stiffness
[in]	eps	restitution coefficient
[in]	mass	effective particle mass, $\frac{2}{1/m1+1/m2}$

Definition at line 176 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, mathsFunc::log(), constants::sqr_pi, mathsFunc::square(), and stiffness_.

 {
     stiffness_ = stiffness;
     if (eps==0.0) {
         dissipation_ = std::sqrt(2.0 * mass * stiffness);
     } else {
         dissipation_ = -std::sqrt(2.0 * mass * stiffness / (constants::sqr_pi + mathsFunc::square(log(eps)))) * log(eps);
     }
 }

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

virtual

Writes the species properties to an output stream.

Parameters

[out] output stream (typically the restart file)

Implements BaseObject.

Definition at line 66 of file LinearViscoelasticNormalSpecies.cc.

References dissipation_, and stiffness_.

 {
     os << " stiffness " << stiffness_
             << " dissipation " << dissipation_;
 }

Member Data Documentation

Mdouble LinearViscoelasticNormalSpecies::dissipation_

private

(normal) viscosity

Definition at line 108 of file LinearViscoelasticNormalSpecies.h.

Referenced by getCollisionTime(), getDissipation(), getRestitutionCoefficient(), LinearViscoelasticNormalSpecies(), mix(), read(), setCollisionTimeAndRestitutionCoefficient(), setDissipation(), setStiffnessAndRestitutionCoefficient(), and write().

Mdouble LinearViscoelasticNormalSpecies::stiffness_

private

(normal) spring constant

Definition at line 107 of file LinearViscoelasticNormalSpecies.h.

Referenced by getCollisionTime(), getMaximumVelocity(), getStiffness(), LinearViscoelasticNormalSpecies(), mix(), read(), setCollisionTimeAndRestitutionCoefficient(), setStiffness(), setStiffnessAndRestitutionCoefficient(), and write().

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

Species/NormalForceSpecies/LinearViscoelasticNormalSpecies.h
Species/NormalForceSpecies/LinearViscoelasticNormalSpecies.cc

Public Types

Public Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation