Rheolef  7.1
an efficient C++ finite element environment
burgers_dg.cc

The Burgers equation by the discontinous Galerkin method

#include "rheolef.h"
using namespace rheolef;
using namespace std;
#include "harten.h"
#include "burgers.icc"
int main(int argc, char**argv) {
environment rheolef (argc, argv);
geo omega (argv[1]);
space Xh (omega, argv[2]);
Float cfl = 1;
limiter_option lopt;
size_t nmax = (argc > 3) ? atoi(argv[3]) : numeric_limits<size_t>::max();
Float tf = (argc > 4) ? atof(argv[4]) : 2.5;
size_t p = (argc > 5) ? atoi(argv[5]) : ssp::pmax;
lopt.M = (argc > 6) ? atoi(argv[6]) : u_init().M();
if (nmax == numeric_limits<size_t>::max()) {
nmax = (size_t)floor(1+tf/(cfl*omega.hmin()));
}
Float delta_t = tf/nmax;
integrate_option iopt;
iopt.invert = true;
trial u (Xh); test v (Xh);
form inv_m = integrate (u*v, iopt);
vector<field> uh(p+1, field(Xh,0));
uh[0] = interpolate (Xh, u_init());
branch even("t","u");
dout << catchmark("delta_t") << delta_t << endl
<< even(0,uh[0]);
for (size_t n = 1; n <= nmax; ++n) {
for (size_t i = 1; i <= p; ++i) {
uh[i] = 0;
for (size_t j = 0; j < i; ++j) {
field lh =
- integrate (dot(compose(f,uh[j]),grad_h(v)))
+ integrate ("internal_sides",
compose (phi, normal(), inner(uh[j]), outer(uh[j]))*jump(v))
+ integrate ("boundary",
compose (phi, normal(), uh[j], g(n*delta_t))*v);
uh[i] += ssp::alpha[p][i][j]*uh[j] - delta_t*ssp::beta[p][i][j]*(inv_m*lh);
}
uh[i] = limiter(uh[i], g(n*delta_t)(point(-1)), lopt);
}
uh[0] = uh[p];
dout << even(n*delta_t,uh[0]);
}
}
The Burgers equation – the f function.
int main(int argc, char **argv)
Definition: burgers_dg.cc:32
u_exact g
u_exact u_init
field lh(Float epsilon, Float t, const test &v)
The Burgers equation – the Godonov flux.
see the Float page for the full documentation
see the branch page for the full documentation
see the field page for the full documentation
see the form page for the full documentation
see the geo page for the full documentation
point_basic< Float > point
Definition: point.h:164
odiststream dout(cout)
see the diststream page for the full documentation
Definition: diststream.h:430
field_basic< Float > field
see the field page for the full documentation
Definition: field.h:419
see the space page for the full documentation
see the test page for the full documentation
see the test page for the full documentation
The Burgers problem: the Harten exact solution.
This file is part of Rheolef.
field_basic< T, M > limiter(const field_basic< T, M > &uh, const T &bar_g_S, const limiter_option &opt)
see the limiter page for the full documentation
Definition: limiter.cc:65
rheolef::std enable_if ::type dot const Expr1 expr1, const Expr2 expr2 dot(const Expr1 &expr1, const Expr2 &expr2)
dot(x,y): see the expression page for the full documentation
Definition: vec_expr_v2.h:415
std::enable_if< details::is_field_convertible< Expr >::value,details::field_expr_v2_nonlinear_terminal_field< typename Expr::scalar_type,typename Expr::memory_type,details::differentiate_option::gradient >>::type grad_h(const Expr &expr)
grad_h(uh): see the expression page for the full documentation
std::enable_if< details::is_field_expr_v2_nonlinear_arg< Expr >::value &&! is_undeterminated< Result >::value, Result >::type integrate(const geo_basic< T, M > &omega, const Expr &expr, const integrate_option &iopt, Result dummy=Result())
see the integrate page for the full documentation
Definition: integrate.h:202
field_basic< T, M > interpolate(const space_basic< T, M > &V2h, const field_basic< T, M > &u1h)
see the interpolate page for the full documentation
Definition: interpolate.cc:233
details::field_expr_v2_nonlinear_node_nary< typename details::function_traits< Function >::functor_type,typename details::field_expr_v2_nonlinear_terminal_wrapper_traits< Exprs >::type... > ::type compose(const Function &f, const Exprs &... exprs)
see the compose page for the full documentation
Definition: compose.h:246
details::field_expr_v2_nonlinear_terminal_function< details::normal_pseudo_function< Float > > normal()
normal: see the expression page for the full documentation
Float beta[][pmax+1][pmax+1]
Float alpha[][pmax+1][pmax+1]
constexpr size_t pmax
rheolef - reference manual
The strong stability preserving Runge-Kutta scheme – coefficients.
Definition: cavity_dg.h:29
Definition: sphere.icc:25
Definition: phi.h:25
Float M() const
Definition: leveque.h:25
Float u(const point &x)