This processing module calculates the wall shear stress and adds it as an extra-field to the output file, and writes it to a surface output file. More...

#include <ProcessWSS.h>

Inheritance diagram for Nektar::FieldUtils::ProcessWSS:

[legend]

Public Member Functions
	ProcessWSS (FieldSharedPtr f)

virtual	~ProcessWSS ()

Public Member Functions inherited from Nektar::FieldUtils::ProcessBoundaryExtract
	ProcessBoundaryExtract (FieldSharedPtr f)

virtual	~ProcessBoundaryExtract ()

Public Member Functions inherited from Nektar::FieldUtils::ProcessModule
	ProcessModule ()

	ProcessModule (FieldSharedPtr p_f)

Public Member Functions inherited from Nektar::FieldUtils::Module
FIELD_UTILS_EXPORT	Module (FieldSharedPtr p_f)

virtual	~Module ()=default

void	Process (po::variables_map &vm)

std::string	GetModuleName ()

std::string	GetModuleDescription ()

const ConfigOption &	GetConfigOption (const std::string &key) const

ModulePriority	GetModulePriority ()

FIELD_UTILS_EXPORT void	RegisterConfig (std::string key, std::string value="")
	Register a configuration option with a module. More...

FIELD_UTILS_EXPORT void	PrintConfig ()
	Print out all configuration options for a module. More...

FIELD_UTILS_EXPORT void	SetDefaults ()
	Sets default configuration options for those which have not been set. More...

FIELD_UTILS_EXPORT void	AddFile (std::string fileType, std::string fileName)

FIELD_UTILS_EXPORT void	EvaluateTriFieldAtEquiSpacedPts (LocalRegions::ExpansionSharedPtr &exp, const Array< OneD, const NekDouble > &infield, Array< OneD, NekDouble > &outfield)

Static Public Member Functions
static std::shared_ptr< Module >	create (FieldSharedPtr f)
	Creates an instance of this class. More...

Static Public Member Functions inherited from Nektar::FieldUtils::ProcessBoundaryExtract
static std::shared_ptr< Module >	create (FieldSharedPtr f)
	Creates an instance of this class. More...

Static Public Attributes
static ModuleKey	className

Static Public Attributes inherited from Nektar::FieldUtils::ProcessBoundaryExtract
static ModuleKey	className

Protected Member Functions
virtual void	v_Process (po::variables_map &vm) override
	Write mesh to output file. More...

virtual std::string	v_GetModuleName () override

virtual std::string	v_GetModuleDescription () override

void	GetViscosity (const Array< OneD, MultiRegions::ExpListSharedPtr > exp, const Array< OneD, Array< OneD, NekDouble >> &BndElmtdPhys, Array< OneD, NekDouble > &mu, NekDouble &lambda)

void	GetVelocity (const Array< OneD, MultiRegions::ExpListSharedPtr > exp, const Array< OneD, Array< OneD, NekDouble >> &BndElmtdPhys, Array< OneD, Array< OneD, NekDouble >> &vel)

Protected Member Functions inherited from Nektar::FieldUtils::ProcessBoundaryExtract
virtual ModulePriority	v_GetModulePriority () override

Protected Member Functions inherited from Nektar::FieldUtils::Module
	Module ()

Private Attributes
int	m_spacedim

Additional Inherited Members
Public Attributes inherited from Nektar::FieldUtils::Module
FieldSharedPtr	m_f
	Field object. More...

Protected Attributes inherited from Nektar::FieldUtils::Module
std::map< std::string, ConfigOption >	m_config
	List of configuration values. More...

std::set< std::string >	m_allowedFiles
	List of allowed file formats. More...

Detailed Description

This processing module calculates the wall shear stress and adds it as an extra-field to the output file, and writes it to a surface output file.

Definition at line 49 of file ProcessWSS.h.

Constructor & Destructor Documentation

◆ ProcessWSS()

Nektar::FieldUtils::ProcessWSS::ProcessWSS ( FieldSharedPtr f )

Definition at line 54 of file ProcessWSS.cpp.

                                        : ProcessBoundaryExtract(f)
 {
 }

◆ ~ProcessWSS()

Nektar::FieldUtils::ProcessWSS::~ProcessWSS ( )

virtual

Definition at line 58 of file ProcessWSS.cpp.

59 {

60 }

Member Function Documentation

◆ create()

static std::shared_ptr<Module> Nektar::FieldUtils::ProcessWSS::create ( FieldSharedPtr f )

inlinestatic

Creates an instance of this class.

Definition at line 53 of file ProcessWSS.h.

     {
         return MemoryManager<ProcessWSS>::AllocateSharedPtr(f);
     }

References Nektar::MemoryManager< DataType >::AllocateSharedPtr().

◆ GetVelocity()

void Nektar::FieldUtils::ProcessWSS::GetVelocity	(	const Array< OneD, MultiRegions::ExpListSharedPtr >	exp,
		const Array< OneD, Array< OneD, NekDouble >> &	BndElmtdPhys,
		Array< OneD, Array< OneD, NekDouble >> &	vel
	)

protected

Definition at line 412 of file ProcessWSS.cpp.

 {
     int npoints = exp[0]->GetNpoints();
     if (boost::iequals(m_f->m_variables[0], "u"))
     {
         // IncNavierStokesSolver
         for (int i = 0; i < m_spacedim; ++i)
         {
             vel[i] = Array<OneD, NekDouble>(npoints);
             Vmath::Vcopy(npoints, BndElmtPhys[i], 1, vel[i], 1);
         }
     }
     else if (boost::iequals(m_f->m_variables[0], "rho") &&
              boost::iequals(m_f->m_variables[1], "rhou"))
     {
         // CompressibleFlowSolver
         for (int i = 0; i < m_spacedim; ++i)
         {
             vel[i] = Array<OneD, NekDouble>(npoints);
             Vmath::Vdiv(npoints, BndElmtPhys[i + 1], 1, BndElmtPhys[0], 1,
                         vel[i], 1);
         }
     }
     else
     {
         // Unknown
         ASSERTL0(false, "Could not identify velocity for WSS");
     }
 }

References ASSERTL0, Nektar::FieldUtils::Module::m_f, m_spacedim, Vmath::Vcopy(), and Vmath::Vdiv().

Referenced by v_Process().

◆ GetViscosity()

void Nektar::FieldUtils::ProcessWSS::GetViscosity	(	const Array< OneD, MultiRegions::ExpListSharedPtr >	exp,
		const Array< OneD, Array< OneD, NekDouble >> &	BndElmtdPhys,
		Array< OneD, NekDouble > &	mu,
		NekDouble &	lambda
	)

protected

Definition at line 303 of file ProcessWSS.cpp.

 {
     NekDouble m_mu;
     int npoints = exp[0]->GetNpoints();
  
     if (boost::iequals(m_f->m_variables[0], "u"))
     {
         // IncNavierStokesSolver
         m_mu = m_f->m_session->GetParameter("Kinvis");
         Vmath::Fill(npoints, m_mu, mu, 1);
         lambda = 0;
     }
     else if (boost::iequals(m_f->m_variables[0], "rho") &&
              boost::iequals(m_f->m_variables[1], "rhou"))
     {
         // CompressibleFlowSolver
         std::string m_ViscosityType;
         m_f->m_session->LoadParameter("mu", m_mu, 1.78e-05);
         m_f->m_session->LoadParameter("lambda", lambda, -2.0 / 3.0);
         m_f->m_session->LoadSolverInfo("ViscosityType", m_ViscosityType,
                                        "Constant");
  
         if (m_ViscosityType == "Variable")
         {
             // Check equation of state
             std::string eosType;
             bool m_idealGas;
             m_f->m_session->LoadSolverInfo("EquationOfState", eosType,
                                            "IdealGas");
             m_idealGas = boost::iequals(eosType, "IdealGas");
             ASSERTL0(
                 m_idealGas,
                 "Only IdealGas EOS implemented for Variable ViscosityType");
  
             // Get relevant parameters
             NekDouble m_gamma;
             NekDouble m_pInf;
             NekDouble m_rhoInf;
             NekDouble m_gasConstant;
             NekDouble cv_inv;
             NekDouble m_Tref;
             NekDouble m_TRatioSutherland;
             m_f->m_session->LoadParameter("Gamma", m_gamma, 1.4);
             m_f->m_session->LoadParameter("pInf", m_pInf, 101325);
             m_f->m_session->LoadParameter("rhoInf", m_rhoInf, 1.225);
             m_f->m_session->LoadParameter("GasConstant", m_gasConstant,
                                           287.058);
             m_f->m_session->LoadParameter("Tref", m_Tref, 288.15);
             m_TRatioSutherland = 110.0 / m_Tref;
  
             // Get temperature from flowfield
             cv_inv = (m_gamma - 1.0) / m_gasConstant;
             // e = 1/rho ( E - 1/2 ( rhou^2/rho + ... ) )
             Array<OneD, NekDouble> tmp(npoints, 0.0);
             Array<OneD, NekDouble> energy(npoints, 0.0);
             Array<OneD, NekDouble> temperature(npoints, 0.0);
  
             Vmath::Vcopy(npoints, BndElmtPhys[m_spacedim + 1], 1, energy, 1);
             for (int i = 0; i < m_spacedim; i++)
             {
                 // rhou^2
                 Vmath::Vmul(npoints, BndElmtPhys[i + 1], 1, BndElmtPhys[i + 1],
                             1, tmp, 1);
                 // rhou^2/rho
                 Vmath::Vdiv(npoints, tmp, 1, BndElmtPhys[0], 1, tmp, 1);
  
                 // 0.5 rhou^2/rho
                 Vmath::Smul(npoints, 0.5, tmp, 1, tmp, 1);
                 // E - 0.5 rhou^2/rho - ...
                 Vmath::Vsub(npoints, energy, 1, tmp, 1, energy, 1);
             }
  
             // rhou^2/rho
             Vmath::Vdiv(npoints, energy, 1, BndElmtPhys[0], 1, energy, 1);
  
             // T = e/Cv
             Vmath::Smul(npoints, cv_inv, energy, 1, temperature, 1);
  
             // Variable viscosity through the Sutherland's law
             //
             // WARNING, if this routine is modified the same must be done in the
             // CompressibleFlowSolver function in VariableConverter.cpp
             // (this class should be restructured).
  
             const NekDouble C = m_TRatioSutherland;
             NekDouble mu_star = m_mu;
             NekDouble T_star  = m_pInf / (m_rhoInf * m_gasConstant);
             NekDouble ratio;
             for (int i = 0; i < npoints; ++i)
             {
                 ratio = temperature[i] / T_star;
                 mu[i] = mu_star * ratio * sqrt(ratio) * (1 + C) / (ratio + C);
             }
         }
         else
         {
             Vmath::Fill(npoints, m_mu, mu, 1);
         }
     }
     else
     {
         // Unknown
         ASSERTL0(false, "Invalid variables for WSS");
     }
 }

References ASSERTL0, Vmath::Fill(), Nektar::FieldUtils::Module::m_f, m_mu, m_rhoInf, m_spacedim, Vmath::Smul(), tinysimd::sqrt(), Vmath::Vcopy(), Vmath::Vdiv(), Vmath::Vmul(), and Vmath::Vsub().

Referenced by v_Process().

◆ v_GetModuleDescription()

virtual std::string Nektar::FieldUtils::ProcessWSS::v_GetModuleDescription ( )

inlineoverrideprotectedvirtual

Reimplemented from Nektar::FieldUtils::ProcessBoundaryExtract.

Definition at line 71 of file ProcessWSS.h.

     {
         return "Calculating wall shear stress";
     }

◆ v_GetModuleName()

virtual std::string Nektar::FieldUtils::ProcessWSS::v_GetModuleName ( )

inlineoverrideprotectedvirtual

Reimplemented from Nektar::FieldUtils::ProcessBoundaryExtract.

Definition at line 66 of file ProcessWSS.h.

     {
         return "ProcessWSS";
     }

◆ v_Process()

void Nektar::FieldUtils::ProcessWSS::v_Process ( po::variables_map & vm )

overrideprotectedvirtual

Write mesh to output file.

Reimplemented from Nektar::FieldUtils::ProcessBoundaryExtract.

Definition at line 62 of file ProcessWSS.cpp.

 {
     ProcessBoundaryExtract::v_Process(vm);
  
     int i, j;
     int nfields = m_f->m_variables.size();
     int expdim  = m_f->m_graph->GetSpaceDimension();
     m_spacedim  = expdim + m_f->m_numHomogeneousDir;
  
     if (m_f->m_exp[0]->GetNumElmts() == 0)
     {
         return;
     }
  
     if (m_spacedim == 1)
     {
         ASSERTL0(false, "Error: wss for a 1D problem cannot "
                         "be computed");
     }
  
     // Declare arrays
     int nshear  = m_spacedim + 1;
     int nstress = m_spacedim * m_spacedim;
     int ngrad   = m_spacedim * m_spacedim;
  
     Array<OneD, Array<OneD, NekDouble>> velocity(nfields);
     Array<OneD, Array<OneD, NekDouble>> grad(ngrad);
     Array<OneD, Array<OneD, NekDouble>> stress(nstress), fstress(nstress);
     Array<OneD, Array<OneD, NekDouble>> fshear(nshear);
  
     Array<OneD, MultiRegions::ExpListSharedPtr> BndExp(nshear);
     Array<OneD, MultiRegions::ExpListSharedPtr> BndElmtExp(nfields);
     Array<OneD, Array<OneD, NekDouble>> BndElmtPhys(nfields);
     Array<OneD, Array<OneD, NekDouble>> BndElmtCoeffs(nfields);
  
     // will resuse nfields expansions to write shear components.
     if (nshear > nfields)
     {
         m_f->m_exp.resize(nshear);
         for (i = nfields; i < nshear; ++i)
         {
             m_f->m_exp[nfields + i] =
                 m_f->AppendExpList(m_f->m_numHomogeneousDir);
         }
     }
  
     // Create map of boundary ids for partitioned domains
     SpatialDomains::BoundaryConditions bcs(m_f->m_session,
                                            m_f->m_exp[0]->GetGraph());
     const SpatialDomains::BoundaryRegionCollection bregions =
         bcs.GetBoundaryRegions();
     map<int, int> BndRegionMap;
     int cnt = 0;
     for (auto &breg_it : bregions)
     {
         BndRegionMap[breg_it.first] = cnt++;
     }
  
     // Loop over boundaries to Write
     for (int b = 0; b < m_f->m_bndRegionsToWrite.size(); ++b)
     {
         if (BndRegionMap.count(m_f->m_bndRegionsToWrite[b]) == 1)
         {
             int bnd = BndRegionMap[m_f->m_bndRegionsToWrite[b]];
             // Get expansion list for boundary and for elements containing this
             // bnd
             for (i = 0; i < nshear; i++)
             {
                 BndExp[i] = m_f->m_exp[i]->UpdateBndCondExpansion(bnd);
             }
  
             Array<OneD, int> ElmtID, edgeID;
             Array<OneD, NekDouble> tmp1, tmp2;
  
             for (i = 0; i < nfields; i++)
             {
                 m_f->m_exp[i]->GetBndElmtExpansion(bnd, BndElmtExp[i]);
                 BndElmtPhys[i] = BndElmtExp[i]->UpdatePhys();
             }
  
             // Get number of points in expansions
             int nqb = BndExp[0]->GetTotPoints();
             int nqe = BndElmtExp[0]->GetTotPoints();
  
             // Initialise local arrays for the velocity gradients, and
             // stress components size of total number of quadrature
             // points for elements in this bnd
             for (i = 0; i < ngrad; ++i)
             {
                 grad[i] = Array<OneD, NekDouble>(nqe);
             }
  
             for (i = 0; i < nstress; ++i)
             {
                 stress[i] = Array<OneD, NekDouble>(nqe);
             }
  
             Array<OneD, NekDouble> div(nqe, 0.0);
  
             // initialise arrays in the boundary
             for (i = 0; i < nstress; ++i)
             {
                 fstress[i] = Array<OneD, NekDouble>(nqb);
             }
  
             for (i = 0; i < nshear; ++i)
             {
                 fshear[i] = Array<OneD, NekDouble>(nqb, 0.0);
             }
  
             // Extract Velocities
             GetVelocity(BndElmtExp, BndElmtPhys, velocity);
  
             // Extract viscosity coefficients
             NekDouble lambda;
             Array<OneD, NekDouble> mu(nqe, 0.0);
             GetViscosity(BndElmtExp, BndElmtPhys, mu, lambda);
  
             // Compute gradients
             for (i = 0; i < m_spacedim; ++i)
             {
                 if (m_spacedim == 2)
                 {
                     BndElmtExp[i]->PhysDeriv(velocity[i],
                                              grad[i * m_spacedim + 0],
                                              grad[i * m_spacedim + 1]);
                 }
                 else
                 {
                     BndElmtExp[i]->PhysDeriv(
                         velocity[i], grad[i * m_spacedim + 0],
                         grad[i * m_spacedim + 1], grad[i * m_spacedim + 2]);
                 }
                 // Add contribution to div(u)
                 Vmath::Vadd(nqe, grad[i * m_spacedim + i], 1, div, 1, div, 1);
             }
  
             // Velocity divergence scaled by lambda * mu
             Vmath::Smul(nqe, lambda, div, 1, div, 1);
             Vmath::Vmul(nqe, mu, 1, div, 1, div, 1);
  
             // Compute stress component terms
             //    tau_ij = mu*(u_i,j + u_j,i) + mu*lambda*delta_ij*div(u)
             for (i = 0; i < m_spacedim; ++i)
             {
                 for (j = i; j < m_spacedim; ++j)
                 {
                     Vmath::Vadd(nqe, grad[i * m_spacedim + j], 1,
                                 grad[j * m_spacedim + i], 1,
                                 stress[i * m_spacedim + j], 1);
  
                     Vmath::Vmul(nqe, mu, 1, stress[i * m_spacedim + j], 1,
                                 stress[i * m_spacedim + j], 1);
  
                     if (i == j)
                     {
                         // Add divergence term to diagonal
                         Vmath::Vadd(nqe, stress[i * m_spacedim + j], 1, div, 1,
                                     stress[i * m_spacedim + j], 1);
                     }
                     else
                     {
                         // Copy to make symmetric
                         Vmath::Vcopy(nqe, stress[i * m_spacedim + j], 1,
                                      stress[j * m_spacedim + i], 1);
                     }
                 }
             }
  
             // Get boundary stress values.
             for (j = 0; j < nstress; ++j)
             {
                 m_f->m_exp[0]->ExtractElmtToBndPhys(bnd, stress[j], fstress[j]);
             }
  
             // Get normals
             Array<OneD, Array<OneD, NekDouble>> normals;
             m_f->m_exp[0]->GetBoundaryNormals(bnd, normals);
             // Reverse normals, to get correct orientation for the body
             for (i = 0; i < m_spacedim; ++i)
             {
                 Vmath::Neg(nqb, normals[i], 1);
             }
  
             // calculate wss, and update coeffs in the boundary expansion
             // S = tau_ij * n_j
             for (i = 0; i < m_spacedim; ++i)
             {
                 for (j = 0; j < m_spacedim; ++j)
                 {
                     Vmath::Vvtvp(nqb, normals[j], 1,
                                  fstress[i * m_spacedim + j], 1, fshear[i], 1,
                                  fshear[i], 1);
                 }
             }
  
             // T = S - (S.n)n
             for (i = 0; i < m_spacedim; ++i)
             {
                 Vmath::Vvtvp(nqb, normals[i], 1, fshear[i], 1,
                              fshear[nshear - 1], 1, fshear[nshear - 1], 1);
             }
             Vmath::Smul(nqb, -1.0, fshear[nshear - 1], 1, fshear[nshear - 1],
                         1);
  
             for (i = 0; i < m_spacedim; i++)
             {
                 Vmath::Vvtvp(nqb, normals[i], 1, fshear[nshear - 1], 1,
                              fshear[i], 1, fshear[i], 1);
                 BndExp[i]->FwdTransLocalElmt(fshear[i],
                                              BndExp[i]->UpdateCoeffs());
             }
  
             // Tw
             Vmath::Zero(nqb, fshear[nshear - 1], 1);
             for (i = 0; i < m_spacedim; ++i)
             {
                 Vmath::Vvtvp(nqb, fshear[i], 1, fshear[i], 1,
                              fshear[nshear - 1], 1, fshear[nshear - 1], 1);
             }
             Vmath::Vsqrt(nqb, fshear[nshear - 1], 1, fshear[nshear - 1], 1);
             BndExp[nshear - 1]->FwdTransLocalElmt(
                 fshear[nshear - 1], BndExp[nshear - 1]->UpdateCoeffs());
         }
     }
  
     if (m_spacedim == 2)
     {
         m_f->m_variables[0] = "Shear_x";
         m_f->m_variables[1] = "Shear_y";
         m_f->m_variables[2] = "Shear_mag";
     }
     else
     {
         m_f->m_variables[0] = "Shear_x";
         m_f->m_variables[1] = "Shear_y";
         m_f->m_variables[2] = "Shear_z";
         m_f->m_variables[3] = "Shear_mag";
     }
 }

References ASSERTL0, Nektar::SpatialDomains::BoundaryConditions::GetBoundaryRegions(), GetVelocity(), GetViscosity(), Nektar::FieldUtils::Module::m_f, m_spacedim, Vmath::Neg(), Vmath::Smul(), Nektar::FieldUtils::ProcessBoundaryExtract::v_Process(), Vmath::Vadd(), Vmath::Vcopy(), Vmath::Vmul(), Vmath::Vsqrt(), Vmath::Vvtvp(), and Vmath::Zero().

Member Data Documentation

◆ className

ModuleKey Nektar::FieldUtils::ProcessWSS::className

static

Initial value:

= GetModuleFactory().RegisterCreatorFunction(
    ModuleKey(eProcessModule, "wss"), ProcessWSS::create,
    "Computes wall shear stress field.")

Definition at line 57 of file ProcessWSS.h.

◆ m_spacedim

int Nektar::FieldUtils::ProcessWSS::m_spacedim

private

Definition at line 85 of file ProcessWSS.h.

Referenced by GetVelocity(), GetViscosity(), and v_Process().

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ProcessWSS()

◆ ~ProcessWSS()

Member Function Documentation

◆ create()

◆ GetVelocity()

◆ GetViscosity()

◆ v_GetModuleDescription()

◆ v_GetModuleName()

◆ v_Process()

Member Data Documentation

◆ className

◆ m_spacedim