swift2::boundaryconditions Namespace Reference

Functions
template<typename Particle >
void	applyFixedBoundaryCondition (Particle &particle, const peano4::datamanagement::VertexMarker &marker, const tarch::la::Vector< Dimensions, double > &domainOffset, const tarch::la::Vector< Dimensions, double > &domainSize, double relativeDomainHalo, int treeId)
	Apply fixed boundary conditions to particle.
std::pair< tarch::la::Vector< Dimensions, double >, tarch::la::Vector< Dimensions, double > >	getUpdateDueToFixedBoundaryCondition (const tarch::la::Vector< Dimensions, double > &particleX, const tarch::la::Vector< Dimensions, double > &particleV, double maxV, double maxDt, double h, const tarch::la::Vector< Dimensions, double > &domainOffset, const tarch::la::Vector< Dimensions, double > &domainSize, double relativeDomainHalo)
	Determine updated position and velocity due to boundary conditions.
bool	isVertexOnGlobalBoundary (const peano4::datamanagement::VertexMarker &marker, const tarch::la::Vector< Dimensions, double > &domainOffset, const tarch::la::Vector< Dimensions, double > &domainSize)

Function Documentation

applyFixedBoundaryCondition()

template<typename Particle >

void swift2::boundaryconditions::applyFixedBoundaryCondition	(	Particle &	particle,
		const peano4::datamanagement::VertexMarker &	marker,
		const tarch::la::Vector< Dimensions, double > &	domainOffset,
		const tarch::la::Vector< Dimensions, double > &	domainSize,
		double	relativeDomainHalo,
		int	treeId )

Apply fixed boundary conditions to particle.

This routine is usually inserted into your code by the action set swift2.api.boundaryconditions.Fixed. It serves as a proxy to the other applyFixedBoundaryCondition(), i.e. forwards the actual position update computation to this routine, and then takes the updated position, writes it into the particle, and logs the position update within the particle database (so all assertions are still correct).

See also

getUpdateDueToFixedBoundaryCondition()

getUpdateDueToFixedBoundaryCondition()

std::pair< tarch::la::Vector< Dimensions, double >, tarch::la::Vector< Dimensions, double > > swift2::boundaryconditions::getUpdateDueToFixedBoundaryCondition	(	const tarch::la::Vector< Dimensions, double > &	particleX,
		const tarch::la::Vector< Dimensions, double > &	particleV,
		double	maxV,
		double	maxDt,
		double	h,
		const tarch::la::Vector< Dimensions, double > &	domainOffset,
		const tarch::la::Vector< Dimensions, double > &	domainSize,
		double	relativeDomainHalo )

Determine updated position and velocity due to boundary conditions.

See applyFixedBoundaryCondition() and notably swift2.api.boundaryconditions.Fixed for some context where this routine is used. Please study notably the generic boundary condition discussion of the project. It provides code snippets how to use this routine.

Algorithm

Our boundary condition handling consists of a series of checks:

• If particles have left the computational domain, we reset them hard to the boundary.
• If particles are close to the boundary and approach it, we damp their velocity.

Close in the last sentence means that they are within a fraction of relativeDomainHalo of the current particle's mesh size. The damping factor is subject to a linear interpolation, i.e. if a particle sits directly on the boundary and moves outside, we damp its velocity by 0. We set the velocity of 0. If it is relativeDomainHalo of the mesh size away from the boundary and approaches it, we multiply this velocity by 1, i.e. we do not damp it. If it is halfway close to the boundary, we multiply the velocity with 0.5 and therefore damp the approach velocity of the particle.

Parameters

relativeDomainHalo

Floating point value between zero and one. If you set it to zero, you disable the velocity damping.

Returns

Tuple of new position and velocity

isVertexOnGlobalBoundary()

bool swift2::boundaryconditions::isVertexOnGlobalBoundary	(	const peano4::datamanagement::VertexMarker &	marker,
		const tarch::la::Vector< Dimensions, double > &	domainOffset,
		const tarch::la::Vector< Dimensions, double > &	domainSize )