From 58678cfc3956ac5a1dbec91392b41b1b73a31463 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sun, 22 Mar 2020 21:08:29 +0100
Subject: Extract hard sphere gas from particle playground

---
 gasplot.py | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 gasplot.py

(limited to 'gasplot.py')

diff --git a/gasplot.py b/gasplot.py
new file mode 100644
index 0000000..8adfe4d
--- /dev/null
+++ b/gasplot.py
@@ -0,0 +1,55 @@
+import numpy as np
+import scipy.stats as stats
+import scipy.constants as const
+from scipy.optimize import minimize
+
+import matplotlib
+import matplotlib.pyplot as plt
+
+from particles import GasFlow, HardSphereSetup, grid_of_random_velocity_particles
+
+grid_width = 30
+radius = 0.002
+char_u = 1120
+
+config = HardSphereSetup(radius, char_u, *grid_of_random_velocity_particles(grid_width, radius, char_u))
+gas = GasFlow(config)
+
+m_nitrogen = 0.028 / const.N_A
+
+def plot(step, velocities):
+    velocities = np.array([np.linalg.norm(v) for v in velocities])
+    maxwellian = stats.maxwell.fit(velocities)
+
+    print("T = %.0f K; u_mean = %.0f [m/s]; energy = %.05f" % ((maxwellian[1]**2 / const.k * m_nitrogen, stats.maxwell.mean(*maxwellian), np.sum([x*2 for x in velocities]))))
+
+    plt.figure()
+
+    plt.ylim(0, 0.003)
+    plt.ylabel('Probability')
+
+    plt.xlim(0, 1.2*char_u)
+    plt.xlabel('Velocity magnitude [m/s]')
+
+    plt.hist(velocities, bins=50, density=True, alpha=0.5, label='Simulated velocities')
+
+    xs = np.linspace(0, 1.2*char_u, 100)
+    plt.plot(xs, stats.maxwell.pdf(xs, *maxwellian), label='Maxwell-Boltzmann distribution')
+
+    plt.legend(loc='upper right')
+
+    plt.savefig("result/%04d.png" % step)
+    plt.close()
+
+def simulate(n_steps, section):
+    for i in range(0, int(n_steps / section)):
+        print("Plot step %d." % (i * section))
+
+        velocities = gas.get_velocities()
+
+        for j in range(0,section):
+            gas.evolve()
+
+        plot(i, velocities)
+
+simulate(10000, 500)
-- 
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