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changeset 1029:dce08a74e0ad feature/advectionRV

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Create a separate class of RungekuttaExteriorRV which uses BDFs for computing the time derivative. Remove BDFs from RungekuttaExteriorRV
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Fri, 11 Jan 2019 15:47:10 +0100
parents 5df155ededcd
children 78c75c95b7dd
files +rv/+time/RungekuttaExteriorRV.m +rv/+time/RungekuttaExteriorRvBdf.m
diffstat 2 files changed, 91 insertions(+), 37 deletions(-) [+]
line wrap: on
line diff
--- a/+rv/+time/RungekuttaExteriorRV.m	Mon Jan 07 16:41:21 2019 +0100
+++ b/+rv/+time/RungekuttaExteriorRV.m	Fri Jan 11 15:47:10 2019 +0100
@@ -24,8 +24,7 @@
     end
     methods
 
-        % TODO: Decide on how to compute dvdt.
-        function obj = RungekuttaExteriorRV(F, k, t0, v0, RV, DvDt, rkOrder, bdfOrders)
+        function obj = RungekuttaExteriorRV(F, k, t0, v0, RV, DvDt, rkOrder)
             obj.F = F;
             obj.k = k;
             obj.t = t0;
@@ -37,23 +36,6 @@
             obj.coeffs = struct('s',s,'a',a,'b',b,'c',c);
         
             obj.RV = RV;
-            %  TBD: Decide on if the initialization of the previous stages used by
-            %       the BDF should be done here, or if it should be checked for each
-            %       step taken.
-            %       If it is moved here, then multiple branching stages can be removed in step()
-            %       but this will effectively result in a plotted simulation starting from n = upperBdfOrder.
-            %       In addition, the properties lowerBdfOrder and upperBdfOrder can be removed.
-            % obj.lowerBdfOrder = bdfOrders.lowerBdfOrder;
-            % obj.upperBdfOrder = bdfOrders.upperBdfOrder;
-            % assert((obj.lowerBdfOrder >= 1) && (obj.upperBdfOrder <= 6));
-            % obj.v_prev = [];
-            % obj.DvDt = rv.time.BdfDerivative();
-            % obj.viscosity = zeros(size(v0));
-            % obj.residual = zeros(size(v0));
-            % obj.dvdt = zeros(size(v0));
-            % obj.Df = zeros(size(v0));
-
-            % Using the ODE:
             obj.DvDt = DvDt;
             obj.dvdt = obj.DvDt(obj.v);
             [obj.viscosity, obj.Df] = RV.evaluate(obj.v,obj.dvdt);
@@ -69,17 +51,7 @@
             state = struct('v', obj.v, 'residual', obj.residual, 'dvdt', obj.dvdt, 'Df', obj.Df, 'viscosity', obj.viscosity, 't', obj.t);
         end
 
-        function obj = step(obj)
-            % % Store current time level and update v_prev
-            % numStoredStages = size(obj.v_prev,2);
-            % if (numStoredStages < obj.upperBdfOrder)
-            %     obj.v_prev = [obj.v, obj.v_prev];
-            %     numStoredStages = numStoredStages+1;
-            % else
-            %     obj.v_prev(:,2:end) = obj.v_prev(:,1:end-1);
-            %     obj.v_prev(:,1) = obj.v;
-            % end
-            
+        function obj = step(obj)            
             obj.dvdt = obj.DvDt(obj.v);
             [obj.viscosity, obj.Df] = obj.RV.evaluate(obj.v,obj.dvdt);
             obj.residual = obj.dvdt + obj.Df;
@@ -89,13 +61,6 @@
             obj.v = time.rk.rungekutta(obj.v, obj.t, obj.k, F_visc, obj.coeffs);
             obj.t = obj.t + obj.k;
             obj.n = obj.n + 1;
-
-            % %Calculate dvdt and evaluate RV for the new time level
-            % if ((numStoredStages >=  obj.lowerBdfOrder) && (numStoredStages <= obj.upperBdfOrder))
-            %     obj.dvdt = obj.DvDt.evaluate(obj.v, obj.v_prev, obj.k);
-            %     [obj.viscosity, obj.Df] = obj.RV.evaluate(obj.v,obj.dvdt);
-            %     obj.residual = obj.dvdt + obj.Df;
-            % end
         end
     end
 end
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+rv/+time/RungekuttaExteriorRvBdf.m	Fri Jan 11 15:47:10 2019 +0100
@@ -0,0 +1,89 @@
+classdef RungekuttaExteriorRvBdf < time.Timestepper
+    properties
+        F       % RHS of the ODE
+        k       % Time step
+        t       % Time point
+        v       % Solution vector
+        n       % Time level
+        coeffs  % The coefficents used for the RK time integration
+        
+        % Properties related to the residual viscositys
+        RV              % Residual Viscosity operator
+        viscosity       % Viscosity vector
+        v_prev          % Solution vector at previous time levels, used for the RV evaluation
+        DvDt            % Function for computing the time deriative used for the RV evaluation
+        lowerBdfOrder   % Orders of the approximation of the time deriative, used for the RV evaluation.
+                        % dictates which accuracy the boot-strapping should start from.
+        upperBdfOrder   % Orders of the approximation of the time deriative, used for the RV evaluation.
+                        % Dictates the order of accuracy used once the boot-strapping is complete.
+        
+        % Convenience properties. Only for plotting
+        residual
+        dvdt
+        Df
+    end
+    methods
+        function obj = RungekuttaExteriorRvBdf(F, k, t0, v0, RV, rkOrder, bdfOrders)
+            obj.F = F;
+            obj.k = k;
+            obj.t = t0;
+            obj.v = v0;
+            obj.n = 0;
+            % Extract the coefficients for the specified rkOrder
+            % used for the RK updates from the Butcher tableua.
+            [s,a,b,c] = time.rk.butcherTableau(rkOrder);
+            obj.coeffs = struct('s',s,'a',a,'b',b,'c',c);
+        
+            obj.RV = RV;
+            %  TBD: Decide on if the initialization of the previous stages used by
+            %       the BDF should be done here, or if it should be checked for each
+            %       step taken.
+            %       If it is moved here, then multiple branching stages can be removed in step()
+            %       but this will effectively result in a plotted simulation starting from n = upperBdfOrder.
+            %       In addition, the properties lowerBdfOrder and upperBdfOrder can be removed.
+            obj.lowerBdfOrder = bdfOrders.lowerBdfOrder;
+            obj.upperBdfOrder = bdfOrders.upperBdfOrder;
+            assert((obj.lowerBdfOrder >= 1) && (obj.upperBdfOrder <= 6));
+            obj.v_prev = [];
+            obj.DvDt = rv.time.BdfDerivative();
+            obj.viscosity = zeros(size(v0));
+            obj.residual = zeros(size(v0));
+            obj.dvdt = zeros(size(v0));
+            obj.Df = zeros(size(v0));
+        end
+
+        function [v, t] = getV(obj)
+            v = obj.v;
+            t = obj.t;
+        end
+
+        function state = getState(obj)
+            state = struct('v', obj.v, 'residual', obj.residual, 'dvdt', obj.dvdt, 'Df', obj.Df, 'viscosity', obj.viscosity, 't', obj.t);
+        end
+
+        function obj = step(obj)
+            % Store current time level and update v_prev
+            numStoredStages = size(obj.v_prev,2);
+            if (numStoredStages < obj.upperBdfOrder)
+                obj.v_prev = [obj.v, obj.v_prev];
+                numStoredStages = numStoredStages+1;
+            else
+                obj.v_prev(:,2:end) = obj.v_prev(:,1:end-1);
+                obj.v_prev(:,1) = obj.v;
+            end
+
+            % Fix the viscosity of the RHS function F
+            F_visc = @(v,t) obj.F(v,t,obj.viscosity);
+            obj.v = time.rk.rungekutta(obj.v, obj.t, obj.k, F_visc, obj.coeffs);
+            obj.t = obj.t + obj.k;
+            obj.n = obj.n + 1;
+
+            %Calculate dvdt and evaluate RV for the new time level
+            if ((numStoredStages >=  obj.lowerBdfOrder) && (numStoredStages <= obj.upperBdfOrder))
+                obj.dvdt = obj.DvDt.evaluate(obj.v, obj.v_prev, obj.k);
+                [obj.viscosity, obj.Df] = obj.RV.evaluate(obj.v,obj.dvdt);
+                obj.residual = obj.dvdt + obj.Df;
+            end
+        end
+    end
+end
\ No newline at end of file