Task 6

Project/AddMass_mult_rot.m

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+function M = AddMass_mult_rot(model, M, c_wall, c_fluid, c_air)
+mesh = model.Mesh;
+nodes = mesh.Nodes;
+elements = mesh.Elements;
+
+Nelems = size(elements,2);
+
+regions = zeros(Nelems,1);
+regions(findElements(mesh,'region','Face',1)) = 1; % wall
+regions(findElements(mesh,'region','Face',2)) = 2; % fluid
+regions(findElements(mesh,'region','Face',3)) = 3; % air
+
+for e = 1:Nelems
+    vert = elements(:,e);
+
+    x = nodes(1,vert);   % r-coordinates
+    y = nodes(2,vert);   % z-coordinates
+
+    Ae = polyarea(x,y);  % element area
+    rbar = mean(x);      % mean radius (axisymmetric weight)
+
+    switch regions(e) % Select heat capacity
+        case 1
+            c = c_wall;
+        case 2
+            c = c_fluid;
+        case 3
+            c = c_air;
+    end
+    % Axisymmetric element mass matrix
+    Me = rbar * c * Ae / 12 * [2 1 1; 1 2 1; 1 1 2];
+    % Assemble
+    M(vert,vert) = M(vert,vert) + Me;
+end
+end