From fe6b7c0e6bd7301badd3f0628f21bfe7e69fd61c Mon Sep 17 00:00:00 2001 From: Brantegger Georg Date: Tue, 28 Jun 2022 14:58:22 +0200 Subject: [PATCH] Found the reason why pressure_surge didn't work as expected -> unintentional overwrite memory address --- Druckrohrleitung/Druckstoß_ETH.ipynb | 93 ++++++++++------------------ 1 file changed, 32 insertions(+), 61 deletions(-) diff --git a/Druckrohrleitung/Druckstoß_ETH.ipynb b/Druckrohrleitung/Druckstoß_ETH.ipynb index 1f22bee..ff176b1 100644 --- a/Druckrohrleitung/Druckstoß_ETH.ipynb +++ b/Druckrohrleitung/Druckstoß_ETH.ipynb @@ -2,7 +2,7 @@ "cells": [ { "cell_type": "code", - "execution_count": 1, + "execution_count": 6, "metadata": {}, "outputs": [], "source": [ @@ -14,7 +14,7 @@ }, { "cell_type": "code", - "execution_count": 2, + "execution_count": 7, "metadata": {}, "outputs": [], "source": [ @@ -27,16 +27,16 @@ "D = 1 # pipe diameter [m]\n", "Q0 = 2 # initial flow in whole pipe [m³/s]\n", "h = 20 # water level in upstream reservoir [m]\n", - "n = 10 # number of pipe segments in discretization\n", - "nt = 11 # number of time steps\n", - "f_D = 0.01 # Darcy friction factor\n", + "n = 10 # number of pipe segments in discretization\n", + "nt = 1500 # number of time steps after initial conditions\n", + "f_D = 0.05 # Darcy friction factor\n", "c = 400 # propagation velocity of the pressure wave [m/s]\n", "\n" ] }, { "cell_type": "code", - "execution_count": 3, + "execution_count": 8, "metadata": {}, "outputs": [], "source": [ @@ -46,14 +46,14 @@ "dt = dx/c # timestep according to method of characterisitics\n", "nn = n+1 # number of nodes\n", "pl_vec = np.arange(0,nn*dx,dx) # pl = pipe-length. position of the nodes on the pipeline\n", - "t_vec = np.arange(0,(nt)*dt,dt) # time vector\n", + "t_vec = np.arange(0,nt*dt,dt) # time vector\n", "\n", "v0 = Q0/(D**2/4*np.pi)\n", "p0 = (rho*g*h-v0**2*rho/2)\n", "\n", "# storage vectors for old parameters\n", "v_old = np.full(nn,v0)\n", - "p_old = p0-(f_D*pl_vec/D*rho/2*v0**2) # ref Wikipedia: Rohrreibungszahls\n", + "p_old = p0-(f_D*pl_vec/D*rho/2*v0**2) # ref Wikipedia: Darcy Weisbach\n", "\n", "# storage vectors for new parameters\n", "v_new = np.zeros_like(v_old)\n", @@ -71,20 +71,9 @@ }, { "cell_type": "code", - "execution_count": 4, + "execution_count": 9, "metadata": {}, - "outputs": [ - { - "data": { - "text/plain": [ - "(-5.092958178940651, 5.092958178940651)" - ] - }, - "execution_count": 4, - "metadata": {}, - "output_type": "execute_result" - } - ], + "outputs": [], "source": [ "%matplotlib qt\n", "# plotting preparation\n", @@ -95,34 +84,20 @@ "\n", "lo_00, = axs1[0].plot(pl_vec,p_old,marker='.')\n", "lo_01, = axs1[1].plot(pl_vec,v_old,marker='.')\n", - "\n", "axs1[0].set_ylim([-20*p0,20*p0])\n", - "axs1[1].set_ylim([-2*v0,2*v0])" + "axs1[1].set_ylim([-2*v0,2*v0])\n", + "fig1.tight_layout()\n", + "plt.pause(1)\n" ] }, { "cell_type": "code", - "execution_count": 5, + "execution_count": 10, "metadata": {}, - "outputs": [ - { - "name": "stdout", - "output_type": "stream", - "text": [ - "8\n", - "[2.54647909 2.54647909 0.03242134 0.02836835 0.02431541 0.02026254\n", - " 0.01620977 0.01215711 0.00810458 0.0040522 0. ]\n", - "9\n", - "[2.54647909 0.03647353 0.03242052 0.02836756 0.02431467 0.02026188\n", - " 0.01620919 0.01215664 0.00810425 0.00405203 0. ]\n", - "10\n", - "[-2.46542799 -2.46568104 -2.46593345 -2.46618518 -2.4664362 -2.46668647\n", - " -2.46693595 -2.46718459 -2.46743236 -2.46767923 0. ]\n" - ] - } - ], + "outputs": [], "source": [ - "for it in range(nt):\n", + "for it in range(1,nt):\n", + "\n", " # set boundary conditions\n", " v_new[-1] = 0 # in front of the instantaneously closing valve, the velocity is 0\n", " p_new[0] = p0 # hydrostatic pressure from the reservoir\n", @@ -142,37 +117,33 @@ " -rho*c*f_D*dt/(4*D)*(abs(v_old[i-1])*v_old[i-1]-abs(v_old[i+1])*v_old[i+1])\n", " \n", "\n", + " # prepare for next loop\n", + " # use .copy() to avoid that memory address is overwritten and hell breaks loose :D\n", + " #https://www.geeksforgeeks.org/array-copying-in-python/\n", + " p_old = p_new.copy()\n", + " v_old = v_new.copy()\n", + "\n", + "\n", " lo_00.set_ydata(p_new)\n", " lo_01.set_ydata(v_new)\n", " \n", " fig1.suptitle(str(it))\n", " fig1.canvas.draw()\n", " fig1.tight_layout()\n", - " plt.pause(0.2)\n", + " plt.pause(0.1)\n", "\n", " # store parameters of node 1 (at reservoir)\n", - " p_1[it] = p_old[0]\n", - " v_1[it] = v_old[0]\n", + " p_1[it] = p_new[0]\n", + " v_1[it] = v_new[0]\n", " # store parameters of node N+1 (at reservoir)\n", - " p_np1[it] = p_old[-1]\n", - " v_np1[it] = v_old[-1]\n", - "\n", - " # prepare for next loop\n", - " p_old = p_new\n", - " v_old = v_new\n", - " if it > 7:\n", - " print(it)\n", - " #print(pressure_conversion(p_new, input_unit= 'Pa', target_unit='Bar'))\n", - " print(v_new)\n", - "\n", - "\n", - "\n" + " p_np1[it] = p_new[-1]\n", + " v_np1[it] = v_new[-1]" ] } ], "metadata": { "kernelspec": { - "display_name": "Python 3.8.13 ('Georg_DT_Slot3')", + "display_name": "Python 3.9.7 ('base')", "language": "python", "name": "python3" }, @@ -186,12 +157,12 @@ "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", - "version": "3.8.13" + "version": "3.9.7" }, "orig_nbformat": 4, "vscode": { "interpreter": { - "hash": "84fb123bdc47ab647d3782661abcbe80fbb79236dd2f8adf4cef30e8755eb2cd" + "hash": "ad2bdc8ecc057115af97d19610ffacc2b4e99fae6737bb82f5d7fb13d2f2c186" } } },