The base class hydro to solve the incompressible Navier-Stokes equations. More...

#include "lib/hydro.h"

Inheritance diagram for hydro:

Public Member Functions
	hydro (const grid &mesh, const parser &solParam, parallel &mpiParam)
	Constructor of the base hydro class. More...

virtual void	solvePDE ()
	The core publicly accessible function of the hydro class to solve the Navier-Stokes equations. More...

virtual real	testPeriodic ()
	Function to test whether periodic BC is being implemented properly. More...

Public Attributes
vfield	V
	The vector field that stores the velocity field.

sfield	P
	The scalar field that stores the pressure field.

force *	vForcing
	Instance of force class to handle velocity field forcing.

Protected Member Functions
void	checkPeriodic ()
	Function to enable/disable periodic data transfer as per the problem. More...

void	setCoefficients ()
	Function to set the coefficients used for solving the implicit equations of U, V and W. More...

void	initVBC ()
	Function to initialize the boundary conditions for velocity. More...

void	imposeUBCs ()
	Function to impose the boundary conditions for the X-component of velocity. More...

void	imposeVBCs ()
	Function to impose the boundary conditions for the Y-component of velocity. More...

void	imposeWBCs ()
	Function to impose the boundary conditions for the Z-component of velocity. More...

void	initVForcing ()
	Function to initialize the forcing terms for velocity. More...

virtual void	solveVx ()
	Function to solve the implicit equation for x-velocity. More...

virtual void	solveVy ()
	Function to solve the implicit equation for y-velocity. More...

virtual void	solveVz ()
	Function to solve the implicit equation for z-velocity. More...

virtual void	timeAdvance ()
	The subroutine to solve the NS equations using the implicit Crank-Nicholson method. More...

Protected Attributes
int	timeStepCount
	Integer value for the number of time-steps elapsed - it is incremented by 1 in each time-step.

int	maxIterations
	Maximum number of iterations for the iterative solvers hydro::solveVx, hydro::solveVy and hydro::solveVz.

real	time

real	dt

real	hx

real	hy

real	hz

real	hx2

real	hz2

real	hz2hx2

real	hx2hy2

real	hy2hz2

real	hx2hy2hz2

const grid &	mesh

const parser &	inputParams

const real	inverseRe

probes *	dataProbe
	Instance of the probe class to collect data from probes in the domain.

boundary *	uLft
	Instances of the boundary class to impose boundary conditions on all the 6 walls for the 3 components of the velocity field.

boundary *	uRgt

boundary *	uFrn

boundary *	uBak

boundary *	uTop

boundary *	uBot

boundary *	vLft

boundary *	vRgt

boundary *	vFrn

boundary *	vBak

boundary *	vTop

boundary *	vBot

boundary *	wLft

boundary *	wRgt

boundary *	wFrn

boundary *	wBak

boundary *	wTop

boundary *	wBot

parallel &	mpiData
	Instance of the parallel class that holds the MPI-related data like rank, xRank, etc.

plainsf	Pp
	Plain scalar field into which the pressure correction is calculated and written by the Poisson solver.

plainsf	mgRHS
	Plain scalar field into which the RHS for pressure Poisson equation is written and passed to the Poisson solver.

plainvf	nseRHS
	Plain vector field into which the RHS of the Navier-Stokes equation is written and stored.

plainvf	velocityLaplacian
	Plain vector field into which the RHS of the implicit equation for velocities are calculated during iterative solving.

plainvf	pressureGradient
	Plain vector field which stores the pressure gradient term.

plainvf	guessedVelocity
	Plain vector field which serves as a temporary array during iterative solution procedure for velocity terms.

Detailed Description

The base class hydro to solve the incompressible Navier-Stokes equations.

The class initializes and stores the velocity vector field and the pressure scalar field along with a few auxilliary fields to solve the PDE. It solves the NSE using the solvePDE function from within which the implicit Crank-Nicholson method is used to solve the PDE.

Constructor & Destructor Documentation

◆ hydro()

hydro::hydro	(	const grid &	mesh,
		const parser &	solParam,
		parallel &	mpiParam
	)

Constructor of the base hydro class.

     The short base constructor of the hydro class merely assigns the const references to the grid and parser
     class instances being used in the solver.
     Also, the maximum allowable number of iterations for the Jacobi iterative solver being used to solve for the
     velocities implicitly is set as \f$ N_{max} = N_x \times N_y \times N_z \f$, where \f$N_x\f$, \f$N_y\f$ and \f$N_z\f$
     are the number of grid points in the collocated grid at the local sub-domains along x, y and z directions
     respectively.

Parameters

mesh	is a const reference to the global data contained in the grid class
solParam	is a const reference to the user-set parameters contained in the parser class

Member Function Documentation

◆ checkPeriodic()

void hydro::checkPeriodic ( )

protected

Function to enable/disable periodic data transfer as per the problem.

     The function checks the xPer, yPer and zPer flags in the parser class
     and enables/disables MPI data transfer at boundaries accordingly
     By default, the MPI neighbours at boundaries are set for periodic data-transfer.
     This has to be disabled if the problem has non-periodic boundaries.

◆ imposeUBCs()

void hydro::imposeUBCs ( )

protected

Function to impose the boundary conditions for the X-component of velocity.

     The function first calls the \ref sfield#syncData "syncData" function of the Vx field to update the sub-domain pads.
     Then the boundary conditions are applied at the full domain boundaries by calling the imposeBC()
     of each boundary class object assigned to each wall.
     The order of imposing boundary conditions is - left, right, front, back, bottom and top boundaries.
     The corner values are not being imposed specifically and is thus dependent on the above order.

◆ imposeVBCs()

void hydro::imposeVBCs ( )

protected

Function to impose the boundary conditions for the Y-component of velocity.

     The function first calls the \ref sfield#syncData "syncData" function of the Vy field to update the sub-domain pads.
     Then the boundary conditions are applied at the full domain boundaries by calling the imposeBC()
     of each boundary class object assigned to each wall.
     The order of imposing boundary conditions is - left, right, front, back, bottom and top boundaries.
     The corner values are not being imposed specifically and is thus dependent on the above order.

◆ imposeWBCs()

void hydro::imposeWBCs ( )

protected

Function to impose the boundary conditions for the Z-component of velocity.

     The function first calls the \ref sfield#syncData "syncData" function of the Vz field to update the sub-domain pads.
     Then the boundary conditions are applied at the full domain boundaries by calling the imposeBC()
     of each boundary class object assigned to each wall.
     The order of imposing boundary conditions is - left, right, front, back, bottom and top boundaries.
     The corner values are not being imposed specifically and is thus dependent on the above order.

◆ initVBC()

void hydro::initVBC ( )

protected

Function to initialize the boundary conditions for velocity.

     The boundary conditions for all the 6 walls (4 in case of 2D simulations) are initialized here.
     Out of the different boundary conditions available in the boundary class,
     the appropriate BCs are chosen according to the type of problem being solved.

◆ initVForcing()

void hydro::initVForcing ( )

protected

Function to initialize the forcing terms for velocity.

     The forcing terms for the velocity field are initialized here.
     Out of the different forcings available in the force class,
     the appropriate forcing is chosen according to the parameters set by the user.

◆ setCoefficients()

void hydro::setCoefficients ( )

protected

Function to set the coefficients used for solving the implicit equations of U, V and W.

     The function assigns values to the variables \ref hx, \ref hy, etc.
     These coefficients are repeatedly used at many places in the Poisson solver for implicit calculation of velocities.

◆ solvePDE()

void hydro::solvePDE ( )

virtual

The core publicly accessible function of the hydro class to solve the Navier-Stokes equations.

     The NSE are integrated in time from within this function by calling \ref hydro#timeAdvance in a loop.
     The function keeps track of the non-dimensional time with \ref time and number of iterations with \ref iterCount.
     Both these values are continuously incremented from within the loop, and finally, when \ref time has reached the
     user-ser value in \ref parser#tMax "tMax", the time-integration loop is broken and the program exits.

Reimplemented in hydro_d2, hydro_d3, scalar_d2, and scalar_d3.

◆ solveVx()

void hydro::solveVx ( )

protectedvirtual

Function to solve the implicit equation for x-velocity.

     The implicit equation for \f$ u_x' \f$ of the implicit Crank-Nicholson method is solved using the Jacobi
     iterative method here.

     The loop exits when the global maximum of the error in computed solution obtained using the \ref plainvf#vxMax "vxMax" function
     of scalar fields in sfield.h falls below the specified tolerance.
     If the solution doesn't converge even after an internally assigned maximum number for iterations, the solver
     aborts with an error message.

     Note that this function uses the blitz index place holders firstIndex, secondIndex and thirdIndex.
     They are declared as i, j, and k respectively.
     Hence the variables i, j and k are not scalars in this function.

◆ solveVy()

void hydro::solveVy ( )

protectedvirtual

Function to solve the implicit equation for y-velocity.

     The implicit equation for \f$ u_y' \f$ of the implicit Crank-Nicholson method is solved using the Jacobi
     iterative method here.

     The loop exits when the global maximum of the error in computed solution obtained using the \ref plainvf#vyMax "vyMax" function
     of scalar fields in sfield.h falls below the specified tolerance.
     If the solution doesn't converge even after an internally assigned maximum number for iterations, the solver
     aborts with an error message.

     Note that this function uses the blitz index place holders firstIndex, secondIndex and thirdIndex.
     They are declared as i, j, and k respectively.
     Hence the variables i, j and k are not scalars in this function.

◆ solveVz()

void hydro::solveVz ( )

protectedvirtual

Function to solve the implicit equation for z-velocity.

     The implicit equation for \f$ u_z' \f$ of the implicit Crank-Nicholson method is solved using the Jacobi
     iterative method here.

     The loop exits when the global maximum of the error in computed solution obtained using the \ref plainvf#vzMax "vzMax" function
     of scalar fields in sfield.h falls below the specified tolerance.
     If the solution doesn't converge even after an internally assigned maximum number for iterations, the solver
     aborts with an error message.

     Note that this function uses the blitz index place holders firstIndex, secondIndex and thirdIndex.
     They are declared as i, j, and k respectively.
     Hence the variables i, j and k are not scalars in this function.

◆ testPeriodic()

real hydro::testPeriodic ( )

virtual

Function to test whether periodic BC is being implemented properly.

     The function populates the arrays with predetermined values at all locations.
     It then calls imposeUBCs, imposeVBCs and imposeWBCs functions and checks if the correct values of the functions are imposed at boundaries

Reimplemented in hydro_d2, hydro_d3, scalar_d2, and scalar_d3.

◆ timeAdvance()

void hydro::timeAdvance ( )

protectedvirtual

The subroutine to solve the NS equations using the implicit Crank-Nicholson method.

     This function uses the values of velocity vector field and pressure scalar field, along with a specifed time-step
     to update the values of both fields by one time-step.
     Hence this function has to be repeatedly called in a loop from within the \ref solvePDE function to solve the equations.

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

src/solvers/hydro/hydro.h
src/solvers/hydro/hydro.cc

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ hydro()

Member Function Documentation

◆ checkPeriodic()

◆ imposeUBCs()

◆ imposeVBCs()

◆ imposeWBCs()

◆ initVBC()

◆ initVForcing()

◆ setCoefficients()

◆ solvePDE()

◆ solveVx()

◆ solveVy()

◆ solveVz()

◆ testPeriodic()

◆ timeAdvance()