forked from lijiext/lammps
78 lines
2.6 KiB
C++
78 lines
2.6 KiB
C++
#include "ViscousStress.h"
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#include "ATC_Error.h"
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#include "LammpsInterface.h"
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#include <iostream>
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#include <fstream>
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namespace ATC {
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//=============================================================================
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// isotropic constant viscosity
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//=============================================================================
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ViscousStressConstant::ViscousStressConstant(fstream &fileId)
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: ViscousStress(), viscosity_(0)
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{
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if (!fileId.is_open()) throw ATC_Error("cannot open material file");
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vector<string> line;
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while(fileId.good()) {
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command_line(fileId, line);
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if (line[0] == "end") {
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if (viscosity_ < 0.0)
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throw ATC_Error("ViscousStressConstant:: bad constant viscosity");
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return;
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}
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else if (line[0]=="viscosity") viscosity_ = str2dbl(line[1]);
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else throw ATC_Error( "viscosity constant - unrecognized material function");
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}
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}
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//=============================================================================
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// compute the stress at N integration points from the velocity gradients
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// T_{ij} = viscosity * du_i/dx_j
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//=============================================================================
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void ViscousStressConstant::viscous_stress(const FIELD_MATS &fields,
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const GRAD_FIELD_MATS &gradFields,
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DENS_MAT_VEC &sigma)
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{
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GRAD_FIELD_MATS::const_iterator du_itr = gradFields.find(VELOCITY);
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const DENS_MAT_VEC &du = du_itr->second;
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CLON_VEC DuxDx(du[0],CLONE_COL,0);
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CLON_VEC DuxDy(du[1],CLONE_COL,0);
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CLON_VEC DuxDz(du[2],CLONE_COL,0);
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CLON_VEC DuyDx(du[0],CLONE_COL,1);
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CLON_VEC DuyDy(du[1],CLONE_COL,1);
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CLON_VEC DuyDz(du[2],CLONE_COL,1);
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CLON_VEC DuzDx(du[0],CLONE_COL,2);
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CLON_VEC DuzDy(du[1],CLONE_COL,2);
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CLON_VEC DuzDz(du[2],CLONE_COL,2);
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const INDEX N = DuxDx.size(); // # of integration pts
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sigma.assign(3, DENS_MAT(N,3));
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// precompute the pressure and copy to the diagonal
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column(sigma[0],0) = DuxDx;
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column(sigma[0],1) = DuyDx;
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column(sigma[0],2) = DuzDx;
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column(sigma[1],0) = DuxDy;
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column(sigma[1],1) = DuyDy;
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column(sigma[1],2) = DuzDy;
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column(sigma[2],0) = DuxDz;
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column(sigma[2],1) = DuyDz;
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column(sigma[2],2) = DuzDz;
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sigma[0] *= -1.*viscosity_;
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sigma[1] *= -1.*viscosity_;
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sigma[2] *= -1.*viscosity_;
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}
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void ViscousStressConstant::viscosity(const FIELD_MATS &fields,
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DENS_MAT &coefs) const
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{
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const DENS_MAT & v = (fields.find(VELOCITY))->second;
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coefs.resize(v.nRows(),v.nCols());
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coefs = -1.*viscosity_;
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}
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}// end atc namespace
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