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annotate +rv/+time/RungekuttaExteriorRV.m @ 1020:5359a61cb4d9 feature/advectionRV

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Add utility for constructing the operators used by a discretization emplying RV-stabilization - Add constructDiffOps which creates the operatores used for a scheme with RV-stabilization - Minor clean up in RungekuttaExteriorRV
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Fri, 14 Dec 2018 18:33:10 +0100
parents 2d7c1333bd6c
children dce08a74e0ad
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 classdef RungekuttaExteriorRV < time.Timestepper
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2 properties
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3 F % RHS of the ODE
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4 k % Time step
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5 t % Time point
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6 v % Solution vector
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7 n % Time level
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8 coeffs % The coefficents used for the RK time integration
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9
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10 % Properties related to the residual viscositys
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11 RV % Residual Viscosity operator
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12 viscosity % Viscosity vector
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13 v_prev % Solution vector at previous time levels, used for the RV evaluation
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14 DvDt % Function for computing the time deriative used for the RV evaluation
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15 lowerBdfOrder % Orders of the approximation of the time deriative, used for the RV evaluation.
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16 % dictates which accuracy the boot-strapping should start from.
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17 upperBdfOrder % Orders of the approximation of the time deriative, used for the RV evaluation.
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18 % Dictates the order of accuracy used once the boot-strapping is complete.
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19
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20 % Convenience properties. Only for plotting
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21 residual
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22 dvdt
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23 Df
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24 end
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25 methods
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26
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27 % TODO: Decide on how to compute dvdt.
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28 function obj = RungekuttaExteriorRV(F, k, t0, v0, RV, DvDt, rkOrder, bdfOrders)
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29 obj.F = F;
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30 obj.k = k;
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31 obj.t = t0;
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32 obj.v = v0;
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33 obj.n = 0;
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34 % Extract the coefficients for the specified rkOrder
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35 % used for the RK updates from the Butcher tableua.
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36 [s,a,b,c] = time.rk.butcherTableau(rkOrder);
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37 obj.coeffs = struct('s',s,'a',a,'b',b,'c',c);
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38
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39 obj.RV = RV;
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40 % TBD: Decide on if the initialization of the previous stages used by
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41 % the BDF should be done here, or if it should be checked for each
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42 % step taken.
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43 % If it is moved here, then multiple branching stages can be removed in step()
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44 % but this will effectively result in a plotted simulation starting from n = upperBdfOrder.
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45 % In addition, the properties lowerBdfOrder and upperBdfOrder can be removed.
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46 % obj.lowerBdfOrder = bdfOrders.lowerBdfOrder;
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47 % obj.upperBdfOrder = bdfOrders.upperBdfOrder;
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48 % assert((obj.lowerBdfOrder >= 1) && (obj.upperBdfOrder <= 6));
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49 % obj.v_prev = [];
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50 % obj.DvDt = rv.time.BdfDerivative();
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51 % obj.viscosity = zeros(size(v0));
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52 % obj.residual = zeros(size(v0));
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53 % obj.dvdt = zeros(size(v0));
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54 % obj.Df = zeros(size(v0));
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55
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56 % Using the ODE:
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57 obj.DvDt = DvDt;
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58 obj.dvdt = obj.DvDt(obj.v);
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59 [obj.viscosity, obj.Df] = RV.evaluate(obj.v,obj.dvdt);
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60 obj.residual = obj.dvdt + obj.Df;
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61 end
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62
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63 function [v, t] = getV(obj)
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64 v = obj.v;
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65 t = obj.t;
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66 end
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67
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68 function state = getState(obj)
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69 state = struct('v', obj.v, 'residual', obj.residual, 'dvdt', obj.dvdt, 'Df', obj.Df, 'viscosity', obj.viscosity, 't', obj.t);
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70 end
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71
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72 function obj = step(obj)
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73 % % Store current time level and update v_prev
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74 % numStoredStages = size(obj.v_prev,2);
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75 % if (numStoredStages < obj.upperBdfOrder)
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76 % obj.v_prev = [obj.v, obj.v_prev];
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77 % numStoredStages = numStoredStages+1;
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78 % else
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79 % obj.v_prev(:,2:end) = obj.v_prev(:,1:end-1);
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80 % obj.v_prev(:,1) = obj.v;
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81 % end
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82
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83 obj.dvdt = obj.DvDt(obj.v);
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84 [obj.viscosity, obj.Df] = obj.RV.evaluate(obj.v,obj.dvdt);
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85 obj.residual = obj.dvdt + obj.Df;
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86
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87 % Fix the viscosity of the RHS function F
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88 F_visc = @(v,t) obj.F(v,t,obj.viscosity);
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89 obj.v = time.rk.rungekutta(obj.v, obj.t, obj.k, F_visc, obj.coeffs);
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90 obj.t = obj.t + obj.k;
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91 obj.n = obj.n + 1;
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92
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93 % %Calculate dvdt and evaluate RV for the new time level
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94 % if ((numStoredStages >= obj.lowerBdfOrder) && (numStoredStages <= obj.upperBdfOrder))
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95 % obj.dvdt = obj.DvDt.evaluate(obj.v, obj.v_prev, obj.k);
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96 % [obj.viscosity, obj.Df] = obj.RV.evaluate(obj.v,obj.dvdt);
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97 % obj.residual = obj.dvdt + obj.Df;
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98 % end
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99 end
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100 end
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101 end