first try at fixing convergence issues at turbine

Untertweng_mit_Pegelregler.ipynb

@@ -42,7 +42,7 @@
     "\n",
     "\n",
     "# pipeline\n",
-    "L               = 535.+478.                     # length of pipeline [m]\n",
+    "L               = (535.+478.)                     # length of pipeline [m]\n",
     "D               = 0.9                           # pipe diameter [m]\n",
     "A_pipe          = D**2/4*np.pi                  # pipeline area\n",
     "h_pipe          = 105                           # hydraulic head without reservoir [m] \n",
@@ -51,7 +51,7 @@
     "f_D             = 0.014                           # Darcy friction factor\n",
     "c               = 500.                          # propagation velocity of the pressure wave [m/s]\n",
     "# consider prescribing a total simulation time and deducting the number of timesteps from that\n",
-    "nt              = 4500                          # number of time steps after initial conditions\n",
+    "nt              = 9000                          # number of time steps after initial conditions\n",
     "\n",
     "# derivatives of the pipeline constants\n",
     "dx              = L/n                           # length of each pipe segment\n",
@@ -184,6 +184,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "error_vec = np.zeros_like(t_vec)\n",
     "# loop through time steps of the pipeline\n",
     "for it_pipe in range(1,pipe.nt+1):\n",
     "\n",
@@ -218,6 +219,7 @@
     "    p_boundary_tur[it_pipe] = pipe.get_current_pressure_distribution()[-1]\n",
     "    v_boundary_res[it_pipe] = pipe.get_current_velocity_distribution()[0]\n",
     "\n",
+    "    error_vec[it_pipe] = abs(v_boundary_res[it_pipe]-V.get_current_outflux()/A_pipe)\n",
     "\n",
     "    # perform the next timestep via the characteristic method\n",
     "    pipe.timestep_characteristic_method()\n",
@@ -288,6 +290,26 @@
     "fig2.tight_layout()\n",
     "plt.show()"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[<matplotlib.lines.Line2D at 0x1ac81d70af0>]"
+      ]
+     },
+     "execution_count": 10,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "plt.semilogy(t_vec,error_vec)"
+   ]
   }
  ],
  "metadata": {