I searched through the mailings lists and found some discussion that
explains that nodal and element data should be stored in an ExplicitSystem,
but could not find any example or explanation to how it should be done.
So, I am working on a test program, but run into a problem when projecting
a "solution". What I am attempting to do in my test code is to create a
TransientExplicitSystem to store a parameter (conductivity). Then using an
equation, I initialize the value across the mesh via projection (I imagine
that I should be able to use projection at any point in time to alter the
values).
The program compiles and links, but produces a PETSc segmentation fault
when executed. I don't understand the concept of using systems for data
storing so I don't have a good feel for what I might be doing wrong.
I would greatly appreciate any help getting this up and running or any
recommendations in general for storing and updating nodal and/or elemental
data.
Thanks,
Andrew
--- MY PROGRAM ---------
// Standard library includes
#include <iostream>
#include <algorithm>
#include <math.h>
#include <stdio.h>
// libMesh includes
#include "libmesh.h"
#include "mesh.h"
#include "mesh_generation.h"
#include "equation_systems.h"
#include "transient_system.h"
#include "explicit_system.h"
#include "analytic_function.h"
#include "vtk_io.h"
// Bring in everything from the libMesh namespace
using namespace libMesh;
// A function for initilizing thermal conductivity
#include <math.h>
#include <boost/math/constants/constants.hpp>
Number initial_conductivity (const Point& p, const Real t){
const double pi = boost::math::constants::pi<double>();
return 1 + exp(-t) * sin(pi*p(0)) * sin(pi*p(1));
}
// Begin main function
int main (int argc, char** argv){
// Initialize libraries
LibMeshInit init (argc, argv);
// Generate a mesh
Mesh mesh;
MeshTools::Generation::build_square(mesh, 10, 10, 0., 1, 0., 1, QUAD4);
mesh.all_second_order();
// Create a system for storing nodal values of conductivity
EquationSystems eq_sys(mesh);
eq_sys.add_system<TransientExplicitSystem>("data");
eq_sys.get_system("data").add_variable("k", SECOND, MONOMIAL);
eq_sys.init();
// Project the initial values of conductivity
AnalyticFunction<Number> func_object(initial_conductivity);
eq_sys.get_system("data").project_solution(&func_object); // segmentation
fault here
// Write conductivity values to a file
//...
return 0;
}
--
Andrew E. Slaughter, PhD
[email protected]
Materials Process Design and Control Laboratory
Sibley School of Mechanical and Aerospace Engineering
169 Frank H. T. Rhodes Hall
Cornell University
Ithaca, NY 14853-3801
(607) 229-1829
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