Nektar::RiemannInvariantBC Class Reference

Outflow characteristic boundary conditions for compressible flow problems. More...

#include <RiemannInvariantBC.h>

Inheritance diagram for Nektar::RiemannInvariantBC:

Static Public Member Functions
static CFSBndCondSharedPtr	create (const LibUtilities::SessionReaderSharedPtr &pSession, const Array< OneD, MultiRegions::ExpListSharedPtr > &pFields, const Array< OneD, Array< OneD, NekDouble >> &pTraceNormals, const int pSpaceDim, const int bcRegion, const int cnt)
	Creates an instance of this class. More...

Static Public Attributes
static std::string	className
	Name of the class. More...

Protected Member Functions
virtual void	v_Apply (Array< OneD, Array< OneD, NekDouble >> &Fwd, Array< OneD, Array< OneD, NekDouble >> &physarray, const NekDouble &time) override
Protected Member Functions inherited from Nektar::CFSBndCond
	CFSBndCond (const LibUtilities::SessionReaderSharedPtr &pSession, const Array< OneD, MultiRegions::ExpListSharedPtr > &pFields, const Array< OneD, Array< OneD, NekDouble >> &pTraceNormals, const int pSpaceDim, const int bcRegion, const int cnt)
	Constructor. More...
virtual void	v_ApplyBwdWeight ()

Protected Attributes
Array< OneD, NekDouble >	m_VnInf
	Reference normal velocity. More...
Protected Attributes inherited from Nektar::CFSBndCond
LibUtilities::SessionReaderSharedPtr	m_session
	Session reader. More...
Array< OneD, MultiRegions::ExpListSharedPtr >	m_fields
	Array of fields. More...
Array< OneD, Array< OneD, NekDouble > >	m_traceNormals
	Trace normals. More...
int	m_spacedim
	Space dimension. More...
VariableConverterSharedPtr	m_varConv
	Auxiliary object to convert variables. More...
NekDouble	m_diffusionAveWeight
	Weight for average calculation of diffusion term. More...
NekDouble	m_gamma
	Parameters of the flow. More...
NekDouble	m_rhoInf
NekDouble	m_pInf
NekDouble	m_pOut
Array< OneD, NekDouble >	m_velInf
int	m_bcRegion
	Id of the boundary region. More...
int	m_offset
	Offset. More...

Private Member Functions
	RiemannInvariantBC (const LibUtilities::SessionReaderSharedPtr &pSession, const Array< OneD, MultiRegions::ExpListSharedPtr > &pFields, const Array< OneD, Array< OneD, NekDouble >> &pTraceNormals, const int pSpaceDim, const int bcRegion, const int cnt)
virtual	~RiemannInvariantBC (void)

Friends
class	MemoryManager< RiemannInvariantBC >

Additional Inherited Members
Public Member Functions inherited from Nektar::CFSBndCond
virtual	~CFSBndCond ()
void	Apply (Array< OneD, Array< OneD, NekDouble >> &Fwd, Array< OneD, Array< OneD, NekDouble >> &physarray, const NekDouble &time=0)
	Apply the boundary condition. More...
void	ApplyBwdWeight ()
	Apply the Weight of boundary condition. More...

Detailed Description

Outflow characteristic boundary conditions for compressible flow problems.

Definition at line 47 of file RiemannInvariantBC.h.

Constructor & Destructor Documentation

RiemannInvariantBC()

Nektar::RiemannInvariantBC::RiemannInvariantBC ( const LibUtilities::SessionReaderSharedPtr &  pSession, const Array< OneD, MultiRegions::ExpListSharedPtr > &  pFields, const Array< OneD, Array< OneD, NekDouble >> &  pTraceNormals, const int  pSpaceDim, const int  bcRegion, const int  cnt  )

private

Definition at line 49 of file RiemannInvariantBC.cpp.

    : CFSBndCond(pSession, pFields, pTraceNormals, pSpaceDim, bcRegion, cnt)
{
    // Calculate VnInf
    int nTracePts = m_fields[0]->GetTrace()->GetNpoints();
    m_VnInf       = Array<OneD, NekDouble>(nTracePts, 0.0);
 
    // Computing the normal velocity for characteristics coming
    // from outside the computational domain
    for (int i = 0; i < m_spacedim; i++)
    {
        Vmath::Svtvp(nTracePts, m_velInf[i], m_traceNormals[i], 1, m_VnInf, 1,
                     m_VnInf, 1);
    }
}

References Nektar::CFSBndCond::m_fields, Nektar::CFSBndCond::m_spacedim, Nektar::CFSBndCond::m_traceNormals, Nektar::CFSBndCond::m_velInf, m_VnInf, and Vmath::Svtvp().

~RiemannInvariantBC()

virtual Nektar::RiemannInvariantBC::~RiemannInvariantBC ( void  )

inlineprivatevirtual

Definition at line 83 of file RiemannInvariantBC.h.

{};

Member Function Documentation

create()

static CFSBndCondSharedPtr Nektar::RiemannInvariantBC::create ( const LibUtilities::SessionReaderSharedPtr &  pSession, const Array< OneD, MultiRegions::ExpListSharedPtr > &  pFields, const Array< OneD, Array< OneD, NekDouble >> &  pTraceNormals, const int  pSpaceDim, const int  bcRegion, const int  cnt  )

inlinestatic

Creates an instance of this class.

Definition at line 53 of file RiemannInvariantBC.h.

    {
        CFSBndCondSharedPtr p =
            MemoryManager<RiemannInvariantBC>::AllocateSharedPtr(
                pSession, pFields, pTraceNormals, pSpaceDim, bcRegion, cnt);
        return p;
    }

References Nektar::MemoryManager< DataType >::AllocateSharedPtr(), and CellMLToNektar.cellml_metadata::p.

v_Apply()

void Nektar::RiemannInvariantBC::v_Apply ( Array< OneD, Array< OneD, NekDouble >> &  Fwd, Array< OneD, Array< OneD, NekDouble >> &  physarray, const NekDouble &  time  )

overrideprotectedvirtual

Implements Nektar::CFSBndCond.

Definition at line 69 of file RiemannInvariantBC.cpp.

{
    boost::ignore_unused(physarray, time);
 
    int i, j;
    int nTracePts   = m_fields[0]->GetTrace()->GetNpoints();
    int nDimensions = m_spacedim;
 
    const Array<OneD, const int> &traceBndMap = m_fields[0]->GetTraceBndMap();
 
    NekDouble gammaInv         = 1.0 / m_gamma;
    NekDouble gammaMinusOne    = m_gamma - 1.0;
    NekDouble gammaMinusOneInv = 1.0 / gammaMinusOne;
 
    // Computing the normal velocity for characteristics coming
    // from inside the computational domain
    Array<OneD, NekDouble> Vn(nTracePts, 0.0);
    Array<OneD, NekDouble> Vel(nTracePts, 0.0);
    for (i = 0; i < nDimensions; ++i)
    {
        Vmath::Vdiv(nTracePts, Fwd[i + 1], 1, Fwd[0], 1, Vel, 1);
        Vmath::Vvtvp(nTracePts, m_traceNormals[i], 1, Vel, 1, Vn, 1, Vn, 1);
    }
 
    // Computing the absolute value of the velocity in order to compute the
    // Mach number to decide whether supersonic or subsonic
    Array<OneD, NekDouble> absVel(nTracePts, 0.0);
    m_varConv->GetAbsoluteVelocity(Fwd, absVel);
 
    // Get speed of sound
    Array<OneD, NekDouble> pressure(nTracePts);
    Array<OneD, NekDouble> soundSpeed(nTracePts);
 
    m_varConv->GetPressure(Fwd, pressure);
    m_varConv->GetSoundSpeed(Fwd, soundSpeed);
 
    // Get Mach
    Array<OneD, NekDouble> Mach(nTracePts, 0.0);
    Vmath::Vdiv(nTracePts, Vn, 1, soundSpeed, 1, Mach, 1);
    Vmath::Vabs(nTracePts, Mach, 1, Mach, 1);
 
    // Auxiliary variables
    int eMax;
    int e, id1, id2, nBCEdgePts, pnt;
    NekDouble cPlus, rPlus, cMinus, rMinus, VDBC, VNBC;
    Array<OneD, NekDouble> velBC(nDimensions, 0.0);
    Array<OneD, NekDouble> rhoVelBC(nDimensions, 0.0);
    NekDouble rhoBC, EBC, cBC, sBC, pBC;
 
    eMax = m_fields[0]->GetBndCondExpansions()[m_bcRegion]->GetExpSize();
 
    // Loop on m_bcRegions
    for (e = 0; e < eMax; ++e)
    {
        nBCEdgePts = m_fields[0]
                         ->GetBndCondExpansions()[m_bcRegion]
                         ->GetExp(e)
                         ->GetTotPoints();
 
        id1 =
            m_fields[0]->GetBndCondExpansions()[m_bcRegion]->GetPhys_Offset(e);
        id2 =
            m_fields[0]->GetTrace()->GetPhys_Offset(traceBndMap[m_offset + e]);
 
        // Loop on the points of the m_bcRegion
        for (i = 0; i < nBCEdgePts; i++)
        {
            pnt = id2 + i;
 
            // Impose inflow Riemann invariant
            if (Vn[pnt] <= 0.0)
            {
                // Subsonic flows
                if (Mach[pnt] < 1.00)
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rPlus = Vn[pnt] + 2.0 * cPlus * gammaMinusOneInv;
 
                    // - Characteristic from boundary
                    cMinus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rMinus = m_VnInf[pnt] - 2.0 * cMinus * gammaMinusOneInv;
                }
                else
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rPlus = m_VnInf[pnt] + 2.0 * cPlus * gammaMinusOneInv;
 
                    // + Characteristic from inside
                    cMinus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rMinus = m_VnInf[pnt] - 2.0 * cPlus * gammaMinusOneInv;
                }
 
                // Riemann boundary variables
                VNBC = 0.5 * (rPlus + rMinus);
                cBC  = 0.25 * gammaMinusOne * (rPlus - rMinus);
                VDBC = VNBC - m_VnInf[pnt];
 
                // Thermodynamic boundary variables
                sBC   = m_pInf / (pow(m_rhoInf, m_gamma));
                rhoBC = pow((cBC * cBC) / (m_gamma * sBC), gammaMinusOneInv);
                pBC   = rhoBC * cBC * cBC * gammaInv;
 
                // Kinetic energy initialiasation
                NekDouble EkBC = 0.0;
 
                // Boundary velocities
                for (j = 0; j < nDimensions; ++j)
                {
                    velBC[j]    = m_velInf[j] + VDBC * m_traceNormals[j][pnt];
                    rhoVelBC[j] = rhoBC * velBC[j];
                    EkBC += 0.5 * rhoBC * velBC[j] * velBC[j];
                }
 
                // Boundary energy
                EBC = pBC * gammaMinusOneInv + EkBC;
 
                // Imposing Riemann Invariant boundary conditions
                (m_fields[0]
                     ->GetBndCondExpansions()[m_bcRegion]
                     ->UpdatePhys())[id1 + i] = rhoBC;
                for (j = 0; j < nDimensions; ++j)
                {
                    (m_fields[j + 1]
                         ->GetBndCondExpansions()[m_bcRegion]
                         ->UpdatePhys())[id1 + i] = rhoVelBC[j];
                }
                (m_fields[nDimensions + 1]
                     ->GetBndCondExpansions()[m_bcRegion]
                     ->UpdatePhys())[id1 + i] = EBC;
            }
            else // Impose outflow Riemann invariant
            {
                // Subsonic flows
                if (Mach[pnt] < 1.00)
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rPlus = Vn[pnt] + 2.0 * cPlus * gammaMinusOneInv;
 
                    // - Characteristic from boundary
                    cMinus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rMinus = m_VnInf[pnt] - 2.0 * cMinus * gammaMinusOneInv;
                }
                else
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rPlus = Vn[pnt] + 2.0 * cPlus * gammaMinusOneInv;
 
                    // + Characteristic from inside
                    cMinus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rMinus = Vn[pnt] - 2.0 * cPlus * gammaMinusOneInv;
                }
 
                // Riemann boundary variables
                VNBC = 0.5 * (rPlus + rMinus);
                cBC  = 0.25 * gammaMinusOne * (rPlus - rMinus);
                VDBC = VNBC - Vn[pnt];
 
                // Thermodynamic boundary variables
                sBC   = pressure[pnt] / (pow(Fwd[0][pnt], m_gamma));
                rhoBC = pow((cBC * cBC) / (m_gamma * sBC), gammaMinusOneInv);
                pBC   = rhoBC * cBC * cBC * gammaInv;
 
                // Kinetic energy initialiasation
                NekDouble EkBC = 0.0;
 
                // Boundary velocities
                for (j = 0; j < nDimensions; ++j)
                {
                    velBC[j] = Fwd[j + 1][pnt] / Fwd[0][pnt] +
                               VDBC * m_traceNormals[j][pnt];
                    rhoVelBC[j] = rhoBC * velBC[j];
                    EkBC += 0.5 * rhoBC * velBC[j] * velBC[j];
                }
 
                // Boundary energy
                EBC = pBC * gammaMinusOneInv + EkBC;
 
                // Imposing Riemann Invariant boundary conditions
                (m_fields[0]
                     ->GetBndCondExpansions()[m_bcRegion]
                     ->UpdatePhys())[id1 + i] = rhoBC;
                for (j = 0; j < nDimensions; ++j)
                {
                    (m_fields[j + 1]
                         ->GetBndCondExpansions()[m_bcRegion]
                         ->UpdatePhys())[id1 + i] = rhoVelBC[j];
                }
                (m_fields[nDimensions + 1]
                     ->GetBndCondExpansions()[m_bcRegion]
                     ->UpdatePhys())[id1 + i] = EBC;
            }
        }
    }
}

References Nektar::CFSBndCond::m_bcRegion, Nektar::CFSBndCond::m_fields, Nektar::CFSBndCond::m_gamma, Nektar::CFSBndCond::m_offset, Nektar::CFSBndCond::m_pInf, Nektar::CFSBndCond::m_rhoInf, Nektar::CFSBndCond::m_spacedim, Nektar::CFSBndCond::m_traceNormals, Nektar::CFSBndCond::m_varConv, Nektar::CFSBndCond::m_velInf, m_VnInf, CG_Iterations::pressure, tinysimd::sqrt(), Vmath::Vabs(), Vmath::Vdiv(), and Vmath::Vvtvp().

Friends And Related Function Documentation

MemoryManager< RiemannInvariantBC >

friend class MemoryManager< RiemannInvariantBC >

friend

Definition at line 1 of file RiemannInvariantBC.h.

Member Data Documentation

className

std::string Nektar::RiemannInvariantBC::className

static

Initial value:

=
    GetCFSBndCondFactory().RegisterCreatorFunction(
        "RiemannInvariant", RiemannInvariantBC::create,
        "Riemann invariant boundary condition.")

Name of the class.

Definition at line 66 of file RiemannInvariantBC.h.

m_VnInf

Array<OneD, NekDouble> Nektar::RiemannInvariantBC::m_VnInf

protected

Reference normal velocity.

Definition at line 74 of file RiemannInvariantBC.h.

Referenced by RiemannInvariantBC(), and v_Apply().