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comparison +rv/+time/RungekuttaExteriorRvMg.m @ 1165:745ae0d134c9 feature/rv

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Pass RHS of unstabilized ode to RKExterirorRvMg
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Thu, 27 Jun 2019 17:14:30 +0200
parents 0ec06ca3fc36
children
comparison
equal deleted inserted replaced
1164:fc2631ba4da5 1165:745ae0d134c9
1 classdef RungekuttaExteriorRvMg < time.Timestepper 1 classdef RungekuttaExteriorRvMg < time.Timestepper
2 properties 2 properties
3 F % RHS of the ODE 3 F % RHS of the ODE
4 F_unstable % RHS of the unstabalized ODE
4 k % Time step 5 k % Time step
5 t % Time point 6 t % Time point
6 v % Solution vector 7 v % Solution vector
7 n % Time level 8 n % Time level
8 rkScheme % The particular RK scheme used for time integration 9 rkScheme % The particular RK scheme used for time integration
11 v_unstable 12 v_unstable
12 viscosity 13 viscosity
13 end 14 end
14 methods 15 methods
15 16
16 function obj = RungekuttaExteriorRvMg(F, k, t0, v0, RV, DvDt, order) 17 function obj = RungekuttaExteriorRvMg(F, F_unstable, k, t0, v0, RV, DvDt, order)
17 obj.F = F; 18 obj.F = F;
19 obj.F_unstable = F_unstable;
18 obj.k = k; 20 obj.k = k;
19 obj.t = t0; 21 obj.t = t0;
20 obj.v = v0; 22 obj.v = v0;
21 obj.n = 0; 23 obj.n = 0;
22 24
42 end 44 end
43 45
44 function state = getState(obj) 46 function state = getState(obj)
45 dvdt = obj.DvDt(obj.v_unstable); 47 dvdt = obj.DvDt(obj.v_unstable);
46 [viscosity, Df, firstOrderViscosity, residualViscosity] = obj.RV.evaluate(obj.v, dvdt); 48 [viscosity, Df, firstOrderViscosity, residualViscosity] = obj.RV.evaluate(obj.v, dvdt);
47 state = struct('v', obj.v, 'dvdt', dvdt, 'Df', Df, 'viscosity', viscosity, 'residualViscosity', residualViscosity, 'firstOrderViscosity', firstOrderViscosity, 't', obj.t); 49 state = struct('v', obj.v, 'dvdt', dvdt, 'Df', Df, 'viscosity', obj.viscosity, 'residualViscosity', residualViscosity, 'firstOrderViscosity', firstOrderViscosity, 't', obj.t);
48 end 50 end
49 51
50 % Advances the solution vector one time step using the Runge-Kutta method given by 52 % Advances the solution vector one time step using the Runge-Kutta method given by
51 % obj.coeffs, using a fixed residual viscosity for the Runge-Kutta substeps 53 % obj.coeffs, using a fixed residual viscosity for the Runge-Kutta substeps
52 function obj = step(obj) 54 function obj = step(obj)
53 % Fix the viscosity of the RHS function F
54 m = length(obj.viscosity); 55 m = length(obj.viscosity);
56 obj.v_unstable = obj.rkScheme(obj.v, obj.t, obj.k, obj.F_unstable);
57 obj.viscosity = obj.RV.evaluateViscosity(obj.v, obj.DvDt(obj.v_unstable));
58 % Fix the viscosity of the stabilized RHS
55 F_stable = @(v,t) obj.F(v,t,spdiags(obj.viscosity,0,m,m)); 59 F_stable = @(v,t) obj.F(v,t,spdiags(obj.viscosity,0,m,m));
56 F_unstable = @(v,t) obj.F(v,t,spdiags(0*obj.viscosity,0,m,m));
57 obj.v = obj.rkScheme(obj.v, obj.t, obj.k, F_stable); 60 obj.v = obj.rkScheme(obj.v, obj.t, obj.k, F_stable);
58 obj.v_unstable = obj.rkScheme(obj.v, obj.t, obj.k, F_unstable);
59 obj.viscosity = obj.RV.evaluateViscosity(obj.v, obj.DvDt(obj.v_unstable));
60 obj.t = obj.t + obj.k; 61 obj.t = obj.t + obj.k;
61 obj.n = obj.n + 1; 62 obj.n = obj.n + 1;
62 end 63 end
63 end 64 end
64 end 65 end