calculate average temperature in mug

mgrid_2/geom.cpp

@@ -496,6 +496,34 @@ void Mesh::Visualize_paraview(vector<double> const &v) const
     return;
 }
 
+double Mesh::AverageVectorFunction_perSubdomain(std::vector<double> &v, int target_sd) const
+{
+    assert(2==Ndims());
+    int const nnode = Nnodes();            // number of vertices in mesh
+    assert( nnode == static_cast<int>(v.size()) );
+
+    double cumulative_element_temp = 0.0;
+    int subdomain_element_counter = 0;
+    for (int e = 0; e < Nelems(); ++e)      // loop over all elements
+    {  
+        int sd = ElementSubdomains[e];      // get subdomain of element e
+        if (sd == target_sd)                // if is target subdomain then
+        {
+            subdomain_element_counter++;
+            int base = e * _nvert_e;        // get starting index of element in coordinate vector
+            double cumulative_node_temp = 0.0;
+            for (int k = 0; k < _nvert_e; ++k)      // loop over vertices of element
+            {
+                int node = _ia[base + k];               // global index of vertex
+                cumulative_node_temp += v[node]; // set function
+            }
+            cumulative_element_temp += cumulative_node_temp/_nvert_e;
+        }
+    }
+
+    return cumulative_element_temp/subdomain_element_counter;
+}
+
 
 
 vector<int> Mesh::Index_DirichletNodes() const

mgrid_2/geom.h

@@ -231,6 +231,9 @@ public:
     [[nodiscard]] virtual std::vector<int> Index_DirichletNodes() const;
 
 
+    [[nodiscard]] double AverageVectorFunction_perSubdomain(std::vector<double> &v, int target_sd) const;
+    
+
     /**
      * Determines the indices of those vertices with Dirichlet boundary conditions.
      * 

mgrid_2/getmatrix.cpp

@@ -433,7 +433,7 @@ double FEM_Matrix::ThermalConductivity(const int subdomain)
     {
         // ceramic mug
         case 0:
-            lambda = 3.0;           // anything from 1 to 4
+            lambda = 4.0;           // anything from 1 to 4
             break;
 
         // water

mgrid_2/main.cpp

@@ -31,7 +31,7 @@ int main(int argc, char **argv )
     // ##########################################
 
     double dt = 1.0;           // time step
-    int steps = 20;            // number of time iterations
+    //int steps = 200;            // number of time iterations
 
     double u0_mug = 18.0;
     double u0_fluid = 80.0;
@@ -76,9 +76,12 @@ int main(int argc, char **argv )
     mesh_c.Init_Solution_mult(uv, 1, [u0_fluid](double x, double y) -> double { return u0_fluid; });  // fluid
     mesh_c.Init_Solution_mult(uv, 2, [u0_air](double x, double y) -> double { return u0_air; });      // air
     
+    //mesh_c.Visualize(uv);
 
     auto t3 = system_clock::now(); // start timer
-    for (int step = 0; step < steps; ++step)
+    double average_cup_temperature = u0_mug;
+    while (average_cup_temperature < 67)
+    //for (int step = 0; step < steps; ++step)
     {
         vector<double> G(Mdt.Nrows(), 0.0);        
         Mdt.Mult(G, uv);                                           // G = M/dt * u_{n}
@@ -91,6 +94,9 @@ int main(int argc, char **argv )
 
         JacobiSolve(SK, H, uv);          // solve: (M/dt + K + C) * u_{n+1}  =  F + M/dt * u_{n}
                                          //        ----- SK -----               ------ H -------
+
+        average_cup_temperature = mesh_c.AverageVectorFunction_perSubdomain(uv, 0);
+        cout << "Average cup temperature: " << average_cup_temperature << endl;
     }
     auto t4 = system_clock::now();  // stop timer