implements a simple one-dimensional finite-diffference solver for the Couette flow. More...

#include <FDCouetteSolver.h>

Inheritance diagram for coupling::solvers::FiniteDifferenceSolver:

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Collaboration diagram for coupling::solvers::FiniteDifferenceSolver:

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Public Member Functions
	FiniteDifferenceSolver (const double channelheight, tarch::la::Vector< 3, double > wallVelocity, const double kinVisc, const double dx, const double dt, const int plotEveryTimestep, const std::string filestem, const tarch::la::Vector< 3, unsigned int > processes, const unsigned int numThreads=1)
	a simple constructor

	~FiniteDifferenceSolver ()
	a simple destructor

void	advance (double dt) override
	advances one time step dt in time and triggers vtk plot if required

tarch::la::Vector< 3, double >	getVelocity (tarch::la::Vector< 3, double > pos) const override
	gets the velocity at a given position

virtual void	setWallVelocity (const tarch::la::Vector< 3, double > wallVelocity) override
	changes the velocity at the moving wall (z=0)

double	getDensity (tarch::la::Vector< 3, double > pos) const override
	returns density at a certain position

void	setMDBoundaryValues (coupling::datastructures::FlexibleCellContainer< 3 > &md2macroBuffer) override
	applies the values received from the MD-solver within the conntinuum solver

Public Member Functions inherited from coupling::solvers::NumericalSolver
	NumericalSolver (const double channelheight, const double dx, const double dt, const double kinVisc, const int plotEveryTimestep, const std::string filestem, const tarch::la::Vector< 3, unsigned int > processes, const Scenario *scen=nullptr)
	a simple constructor

virtual	~NumericalSolver ()
	a simple destructor

void	setMDBoundary (tarch::la::Vector< 3, double > mdDomainOffset, tarch::la::Vector< 3, double > mdDomainSize, unsigned int overlapStrip)
	flags the domain boundary cells.

tarch::la::Vector< 3, unsigned int >	getNumberProcesses () const
	returns the number of process, regards parallel runs

tarch::la::Vector< 3, unsigned int >	getAvgNumberLBCells () const
	returns the average number of cells on each process

Public Member Functions inherited from coupling::solvers::AbstractCouetteSolver< 3 >
virtual	~AbstractCouetteSolver ()
	a dummy destructor

virtual tarch::la::Vector< dim, double >	getVelocity (tarch::la::Vector< dim, double > pos) const=0
	returns the current velocity at the given position

virtual void	setWallVelocity (const tarch::la::Vector< dim, double > wallVelocity)=0
	changes the velocity at the moving for, refers to Couette scenario

Private Member Functions
void	setBeyondWall ()
	updates the velocities at boundaries

void	update ()
	update the velocity in the cells which are flagged as FLUID

Private Attributes
const double	_omega
	factor for the finite difference stencil = dtkinVisc/(dxdx)

tarch::la::Vector< 3, double >	_wallVelocity
	velocity of moving wall of Couette flow

double *	_velold {nullptr}
	the velocity field from the last time step

Additional Inherited Members
Static Public Member Functions inherited from coupling::solvers::NumericalSolver
static int	getAvgDomainSize (double channelheight, double dx, tarch::la::Vector< 3, unsigned int > processes, int d)

Protected Types inherited from coupling::solvers::NumericalSolver
enum	Flag { FLUID = 0 , NO_SLIP = 1 , MOVING_WALL = 2 , PERIODIC = 3 , MD_BOUNDARY = 4 , PARALLEL_BOUNDARY = 5 }
	for every cell exists a flag entry, upon this is defined how the cell is handled More...

enum	NbFlag { LEFT = 0 , RIGHT = 1 , BACK = 2 , FRONT = 3 , BOTTOM = 4 , TOP = 5 }
	The flags are used on parallel boundaries to define in which direction the boundary goes. More...

Protected Member Functions inherited from coupling::solvers::NumericalSolver
int	get (int i) const
	returns i and performs checks in debug mode

int	get (int x, int y, int z) const
	returns linearized index and performs checks in debug mode

int	getParBuf (int x, int y, int lengthx, int lengthy) const
	returns index in 2D parallel buffer with buffer dimensions lengthx+2,lengthy+2. Performs checks in debug mode

void	plot () const

void	plot (std::string filename) const
	create vtk plot if required

bool	skipRank () const
	returns true, if this rank is not of relevance for the LB simulation

Protected Attributes inherited from coupling::solvers::NumericalSolver
const double	_channelheight
	the height and width of the channel in z and y direction

const double	_dx
	mesh size, dx=dy=dz

const double	_dt
	time step

const double	_kinVisc
	kinematic viscosity of the fluid

tarch::la::Vector< 3, unsigned int >	_processes
	domain decomposition on MPI rank basis; total number is given by multipling all entries

const int	_plotEveryTimestep
	number of time steps between vtk plots

const std::string	_filestem
	file stem for vtk plot

const int	_domainSizeX {getDomainSize(_channelheight, _dx, _processes, 0)}
	domain size in x-direction

const int	_domainSizeY {getDomainSize(_channelheight, _dx, _processes, 1)}
	domain size in y-direction

const int	_domainSizeZ {getDomainSize(_channelheight, _dx, _processes, 2)}
	domain size in z-direction

const int	_avgDomainSizeX {getAvgDomainSize(_channelheight, _dx, _processes, 0)}
	avg. domain size in MPI-parallel simulation in x-direction

const int	_avgDomainSizeY {getAvgDomainSize(_channelheight, _dx, _processes, 1)}
	avg. domain size in MPI-parallel simulation in y-direction

const int	_avgDomainSizeZ {getAvgDomainSize(_channelheight, _dx, _processes, 2)}
	avg. domain size in MPI-parallel simulation in z-direction

const tarch::la::Vector< 3, unsigned int >	_coords {getProcessCoordinates()}
	coordinates of this process (=1,1,1, unless parallel run of the solver )

int	_counter {0}
	time step counter

double *	_vel {NULL}
	velocity field

double *	_density {NULL}
	density field

Flag *	_flag {NULL}
	flag field

double *	_sendBufferX {NULL}
	buffer to send data from left/right to right/left neighbour

double *	_recvBufferX {NULL}
	buffer to receive data from from left/right neighbour

double *	_sendBufferY {NULL}
	buffer to send data from front/back to front/back neighbour

double *	_recvBufferY {NULL}
	buffer to receive data from from front/back neighbour

double *	_sendBufferZ {NULL}
	buffer to send data from top/buttom to top/buttom neighbour

double *	_recvBufferZ {NULL}
	buffer to receive data from from top/buttom neighbour

const int	_xO {_domainSizeX + 2}
	offset for y-direction (lexicographic grid ordering)

const int	_yO {(_domainSizeX + 2) * (_domainSizeY + 2)}
	offset for z-direction

tarch::la::Vector< 6, int >	_parallelNeighbours {(-1)}
	neighbour ranks

tarch::la::Vector< 3, int >	_offset {(-1)}
	offset of the md domain

tarch::la::Vector< 3, int >	_globalNumberCouplingCells {(-1)}
	the total number of coupling cells of the coupled simulation

const Scenario *	_scen

Detailed Description

implements a simple one-dimensional finite-diffference solver for the Couette flow.

In our scenario, the lower wall is accelerated and the upper wall stands still. The lower wall is located at zero height. The grid is just a simple cubic, equidistant mesh.

Author: Helene Wittenberg

Constructor & Destructor Documentation

◆ FiniteDifferenceSolver()

coupling::solvers::FiniteDifferenceSolver::FiniteDifferenceSolver	(	const double	channelheight,
		tarch::la::Vector< 3, double >	wallVelocity,
		const double	kinVisc,
		const double	dx,
		const double	dt,
		const int	plotEveryTimestep,
		const std::string	filestem,
		const tarch::la::Vector< 3, unsigned int >	processes,
		const unsigned int	numThreads = 1 )

inline

a simple constructor

Parameters

channelheight	the width and height of the channel in y and z direction
kinVisc	the kinematic viscosity of the fluid
wallVelocity	velocity at the moving wall, refers to Couette scenario
dx	the spacial step size, and equidistant grid is applied
dt	the time step
plotEveryTimestep	the time step interval for plotting data; 4 means, every 4th time step is plotted
filestem	the name of the plotted file
processes	defines on how many processes the solver will run; 1,1,1 - sequential run - 1,2,2 = 122 = 4 processes
numThreads	number of OpenMP threads

Member Function Documentation

◆ advance()

void coupling::solvers::FiniteDifferenceSolver::advance ( double dt )

inlineoverridevirtual

advances one time step dt in time and triggers vtk plot if required

Implements coupling::solvers::AbstractCouetteSolver< 3 >.

◆ getDensity()

double coupling::solvers::FiniteDifferenceSolver::getDensity ( tarch::la::Vector< 3, double > pos ) const

inlineoverridevirtual

returns density at a certain position

Parameters

pos	position for which the density will be returned

Returns: a density vector

Implements coupling::solvers::NumericalSolver.

◆ getVelocity()

tarch::la::Vector< 3, double > coupling::solvers::FiniteDifferenceSolver::getVelocity ( tarch::la::Vector< 3, double > pos ) const

inlineoverride

gets the velocity at a given position

Parameters

pos	a position within the continuum domain

Returns: the velocity vector

◆ setBeyondWall()

void coupling::solvers::FiniteDifferenceSolver::setBeyondWall ( )

inlineprivate

updates the velocities at boundaries

there is no grid point on the wall, since the wall is located directly between the cells on the boundary. Therefore so set the boundary condition, the velocity boundary condition is applied by setting the velocity in the outer cell

◆ setMDBoundaryValues()

void coupling::solvers::FiniteDifferenceSolver::setMDBoundaryValues ( coupling::datastructures::FlexibleCellContainer< 3 > & md2macroBuffer )

inlineoverridevirtual

applies the values received from the MD-solver within the conntinuum solver

Parameters

recvBuffer	holds the data from the md solver
recvIndice	the indices to connect the data from the buffer with coupling cells

Implements coupling::solvers::NumericalSolver.

◆ setWallVelocity()

virtual void coupling::solvers::FiniteDifferenceSolver::setWallVelocity ( const tarch::la::Vector< 3, double > wallVelocity )

inlineoverridevirtual

changes the velocity at the moving wall (z=0)

Parameters

wallVelocity the velocity will be set at the moving wall

Implements coupling::solvers::NumericalSolver.

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

coupling/solvers/FDCouetteSolver.h

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FiniteDifferenceSolver()

Member Function Documentation

◆ advance()

◆ getDensity()

◆ getVelocity()

◆ setBeyondWall()

◆ setMDBoundaryValues()

◆ setWallVelocity()