Rheolef  7.2
an efficient C++ finite element environment
 
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zalesak_circle_dg.cc
Go to the documentation of this file.
1
25#include "rheolef.h"
26using namespace rheolef;
27using namespace std;
28#include "zalesak_circle.h"
29#include "bdf.icc"
30int main(int argc, char**argv) {
31 environment rheolef (argc, argv);
32 geo omega (argv[1]);
33 space Xh (omega, argv[2]);
34 size_t n_max = (argc > 3) ? atoi(argv[3]) : 1000;
35 size_t strip = (argc > 4) ? string(argv[4]) == "true" : false;
36 size_t p = (argc > 5) ? atoi(argv[5]) : min(Xh.degree()+1,bdf::pmax);
37 Float tf = u::period(), delta_t = tf/n_max;
38 trial phi (Xh); test xi (Xh);
39 form m = integrate (phi*xi),
40 a0 = integrate (dot(u(),grad_h(phi))*xi)
41 + integrate ("boundary", max(0, -dot(u(),normal()))*phi*xi)
42 + integrate ("internal_sides",
43 - dot(u(),normal())*jump(phi)*average(xi)
44 + 0.5*abs(dot(u(),normal()))*jump(phi)*jump(xi));
45 problem pb;
46 branch event ("t","phi");
47 vector<field> phi_h (p+1);
48 phi_h[0] = phi_h[1] = lazy_interpolate (Xh, phi0());
49 dout << event (0, phi_h[0]);
50 for (size_t n = 1; n <= n_max; n++) {
51 Float t = n*delta_t;
52 if (n % 10 == 0) derr << "[" << n << "]";
53 size_t pn = min(n,p);
54 field rhs(Xh, 0);
55 for (size_t i = 1; i <= pn; i++)
56 rhs += (bdf::alpha[pn][i]/delta_t)*phi_h[i];
57 field lh = integrate(rhs*xi)
58 + integrate("boundary", max(0,-dot(u(),normal()))*phi_exact(t)*xi);
59 if (pn <= p) {
60 form an = a0 + (bdf::alpha[pn][0]/delta_t)*m;
61 pb = problem (an);
62 }
63 pb.solve (lh, phi_h[0]);
64 check_macro (phi_h[0].max_abs() < 100, "BDF failed -- HINT: decrease delta_t");
65 if (!strip || n == n_max) dout << event (t, phi_h[0]);
66 for (size_t i = min(p,pn+1); i >= 1; i--)
67 phi_h[i] = phi_h[i-1];
68 }
69 derr << endl;
70}
BDF(p) backward differentiation formula – coefficients.
field lh(Float epsilon, Float t, const test &v)
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
see the problem page for the full documentation
see the environment page for the full documentation
see the space page for the full documentation
see the test page for the full documentation
see the test page for the full documentation
int main()
Definition field2bb.cc:58
check_macro(expr1.have_homogeneous_space(Xh1), "dual(expr1,expr2); expr1 should have homogeneous space. HINT: use dual(interpolate(Xh, expr1),expr2)")
Float alpha[pmax+1][pmax+1]
Definition bdf.icc:28
constexpr size_t pmax
Definition bdf.icc:26
This file is part of Rheolef.
field_basic< T, M > lazy_interpolate(const space_basic< T, M > &X2h, const field_basic< T, M > &u1h)
see the interpolate page for the full documentation
Definition field.h:871
std::enable_if< details::has_field_rdof_interface< Expr >::value, details::field_expr_v2_nonlinear_terminal_field< typenameExpr::scalar_type, typenameExpr::memory_type, details::differentiate_option::gradient > >::type grad_h(const Expr &expr)
grad_h(uh): see the expression page for the full documentation
details::field_expr_v2_nonlinear_terminal_function< details::normal_pseudo_function< Float > > normal()
normal: 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:211
rheolef::std enable_if ::type dot const Expr1 expr1, const Expr2 expr2 dot(const Expr1 &expr1, const Expr2 &expr2)
STL namespace.
rheolef - reference manual
Definition sphere.icc:25
Definition leveque.h:37
Definition phi.h:25
Definition leveque.h:25
static Float period()
Definition leveque.h:32
The Zalesak full disk benchmark – the exact solution.