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Simple particle with a fixed interaction radius h which moves according to leapfrog KDK scheme. More...

Inheritance diagram for swift2.particle.tests.DisappearingParticleTest.DisappearingParticleTest:

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Collaboration diagram for swift2.particle.tests.DisappearingParticleTest.DisappearingParticleTest:

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Public Member Functions
	__init__ (self, name, cfl_factor, initial_time_step_size, particle_particle_interaction_over_particle_sets_kernel="", touch_particles_of_set_first_time_kernel="", touch_particles_of_set_last_time_kernel="")
	Initialise the particle.

	algorithm_steps (self)
	Leapfrog consists basically of four steps per particle.

	initialisation_steps (self)
	No particular initialisation required.

Public Member Functions inherited from swift2.particle.Particle.Particle
	readme_descriptor (self)
	Create default readme descriptor.

Public Member Functions inherited from peano4.datamodel.DaStGen2.DaStGen2
	configure (self, namespace, association, subdirectory="")
	I always need the MPI aspect, but I can't add the right one before I don't know whether this DaStGen model is used for vertices, faces or cells.

	additional_load_and_store_arguments (self)

	additional_load_and_store_arguments (self, new_arguments)

Public Member Functions inherited from peano4.datamodel.DoF.DoF
	get_full_qualified_type (self)

	get_logical_type_name (self)
	What should the data type be called within the data repository, or within action sets.

	get_enumeration_type (self)
	What should the data type be called within the data repository.

	additional_load_and_store_arguments_for_other_dof (self, argument_name, use_dof_association=None)
	You can make Peano's store and load arguments of any DoF depend on other DoFs that you have loaded before.

	subnamespace (self)

Data Fields
	cfl_factor

	initial_time_step_size

	velocity

	accelerator

	v_full

	u_full

	u

	density

	pressure

	soundSpeed

	v_sig_AV

	particle_particle_interaction_over_particle_sets_kernel

	touch_particles_of_set_first_time_kernel

	touch_particles_of_set_last_time_kernel

	name

Data Fields inherited from swift2.particle.Particle.Particle
	particles_per_cell

	min_h

	max_h

	name

Data Fields inherited from peano4.toolbox.particles.Particle.Particle
	name

	partid

Data Fields inherited from peano4.datamodel.DaStGen2.DaStGen2
	generator

	data

	peano4_mpi_and_storage_aspect

Data Fields inherited from peano4.datamodel.DoF.DoF
	association

	name

	namespace

	subdirectory

Additional Inherited Members
Static Public Attributes inherited from swift2.particle.Particle.Particle
str	DependencyChecks_Attribute_Prefix = "dependencyChecks"

list	DependencyChecks_Ifdefs = ["PeanoDebug > 0"]

Static Public Attributes inherited from peano4.datamodel.DaStGen2.DaStGen2
str	readme_package_descriptor

Protected Member Functions inherited from swift2.particle.Particle.Particle
	_dependency_checks_modify_steps (self, steplist, step_type_name, peano4_event_enum)
	Add dependency checks as well as mesh consistency checks to the algorithm steps.

	_add_dependency_checks (self)
	Add dependency (particle consistency) checks.

Protected Attributes inherited from swift2.particle.Particle.Particle
	_algorithm_steps

	_initialisation_steps

Protected Attributes inherited from peano4.datamodel.DaStGen2.DaStGen2
	_additional_load_and_store_arguments

Protected Attributes inherited from peano4.datamodel.DoF.DoF
	_additional_load_and_store_arguments

Detailed Description

Simple particle with a fixed interaction radius h which moves according to leapfrog KDK scheme.

By default, it uses global time stepping, i.e. the combination of maximum velocity and minimal mesh size determines the time step size of the subsequent time step. Besides the default variables x and h, the particle has the following properties:

a vector a which is the acceleration;
a vector v which is the velocity.

You can add further properties via

   myparticle.data.add_attribute( peano4.dastgen2.Peano4DoubleArray("myFancyArray","Dimensions") )

in your code. Or you can create a subclass which adds additional fields after it has called the baseline constructor.

You will need to add further properties for any SPH project.

Force calculation

particle_particle_interaction_over_particle_sets_kernel is a C++ string which defines a force between two particles. It has access to three important objects:

localParticles is a container (list) over pointers to local particles
activeParticles is a container (list) over pointers to active particles
marker is a cell marker which identifies the current cell.

Please consult the guidebook for a definition of local and active particles but take into account that the local particles always are a subset of the active particles.

Besides the actual particle-to-particle calculation, i.e. a force calculation, users can also provide kernels that kick in when you touch particles for the first time before you actually compute any particle-particle interaction, and there is a plug-in point what you do just once the particle-particle interaction has terminated. The latter point is reached before we do the actual time stepping. In both plug-in points, you have a vertex marker which gives you the position of the vertex to which a particular is associated, and you have the localParticles. This is a vector of pointers in this particular case.

See also: peano4::datamanagement::CellMarker; peano4::datamanagement::VertexMarker

Definition at line 11 of file DisappearingParticleTest.py.

Constructor & Destructor Documentation

◆ init()

swift2.particle.tests.DisappearingParticleTest.DisappearingParticleTest.__init__	(	self,
		name,
		particles_per_cell,
		min_h,
		max_h = "",
		touch_particles_of_set_first_time_kernel = "",
		touch_particles_of_set_last_time_kernel = "" )

Initialise the particle.

This is the baseclass for a particle, i.e. we only add the absolute minimum of information to a particle. As we inherit from the toolbox particle, we already have some attributes defined. These are the guys which are not explicitly visible from the code snippet below, i.e. they are introduced by the superclass constructor.

Here's an overview of pre-defined attributes that each and every particle hosts:

A position which is a double vector with Dimension entries.
A search radius which describes the range with which other particles a particle might theoretically interact. The effective interaction might be smaller if a code decides to ignore potential interaction partners, i.e. this is an absolute maximum. The search radius will decide on which resolution level within the tree a particle is held.
A MoveState flag. This flag is essential. We use it later to label those particles that have been moved to avoid that we move particles multiple times.
A flag that indicates if a particle has been updated within a cell. Consult our code release papers: In short, a particle does not uniquely belong to one cell but can belong to many cells. We nevertheless want to update them only once.

See also: swift2.actionsets.UpdateParticleMarker

Reimplemented from swift2.particle.Particle.Particle.

Definition at line 61 of file DisappearingParticleTest.py.

References swift2.particle.tests.DisappearingParticleTest.DisappearingParticleTest.__init__().

Referenced by swift2.particle.tests.DisappearingParticleTest.DisappearingParticleTest.__init__().

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Member Function Documentation

◆ algorithm_steps()

swift2.particle.tests.DisappearingParticleTest.DisappearingParticleTest.algorithm_steps ( self )

Leapfrog consists basically of four steps per particle.

We first determine the force. Then we update the velocity by half a timestep and move the particle by a full timestep. Then the force is re-computed and the second half of the velocity update is done. Some variations of this KDK form re-arrange the steps executed per timestep to avoid a second force loop.

Reimplemented from swift2.particle.Particle.Particle.

Definition at line 111 of file DisappearingParticleTest.py.