From 3a71ede91713ec1dc9521237535496ff4969f59a Mon Sep 17 00:00:00 2001
From: Jens Ahrensfeld <jens@jayfield.org>
Date: Mon, 2 Dec 2024 15:41:41 +0100
Subject: [PATCH] added luftwiderstand

---
 luftwiderstand.py | 110 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 luftwiderstand.py

diff --git a/luftwiderstand.py b/luftwiderstand.py
new file mode 100644
index 0000000..40347eb
--- /dev/null
+++ b/luftwiderstand.py
@@ -0,0 +1,110 @@
+from matplotlib import pyplot as plot
+import numpy as np
+temperatures = []
+
+# Standard-Atmosphärendruck [Pa]
+g_p0 = 101325
+
+# spezifischen Gaskonstante R_S = R/M = 287,058   J/(kg*K) für trockene Luft
+g_RS = 287.54
+
+# CW-Wert und Stirnfläche
+c_val_id3 = 0.267
+area_id3 = 2.360	# m^3
+
+car_list = [
+	{
+		"car": "VW id.3",
+		"cw": 0.267,
+		"area": 2.360
+	},
+	{
+		"car": "Tesla Model Y LR AWD",
+		"cw": 0.23,
+		"area": 2.518
+	},
+	{
+		"car": "Tesla Model 3 LR AWD",
+		"cw": 0.23,
+		"area": 2.220
+	},
+	{
+		"car": "Polestar 2",
+		"cw": 0.278,
+		"area": 2.480
+	},
+	{
+		"car": "Renault Zoe",
+		"cw": 0.33,
+		"area": 2.27
+	},
+	{
+		"car": "Hyundai Kona Elektro",
+		"cw": 0.29,
+		"area": 2.37
+	},
+	{
+		"car": "Hyundai Ioniq Elektro",
+		"cw": 0.24,
+		"area": 2.22
+	}
+]
+
+# rho: [kg/m3]
+def rho(temperature_degc: float, p_pa: float =g_p0):
+	return p_pa/(g_RS*(temperature_degc + 273.15))
+
+
+# Force : N = kg·m·s2
+def fd(rho: float, velocity_kmh: float, c_val: float, area: float):
+	vel = velocity_kmh / 3.6
+	cwa = c_val * area
+	res = 0.5*rho*vel*vel*cwa
+	return res
+
+
+plot.figure()
+
+# Fd vs. velocity, param: temperature
+temps_list = [-20, -10, 0, 10, 20, 30]
+vel_list = [20, 40, 60, 80, 100, 120, 130, 140, 160]
+reference = fd(rho(20), 100, c_val_id3, area_id3)
+temps_list_leg = [f"{t}°C" for t in temps_list]
+
+for temp_degc in temps_list:
+	rho_t = rho(temp_degc)
+	y_fd = []
+	for vel_kmh in vel_list:
+		fd_t = (fd(rho_t, vel_kmh, c_val_id3, area_id3)/reference - 1) * 100
+		y_fd.append(fd_t)
+
+	plot.plot(vel_list, y_fd)
+
+plot.ylabel("Wind-Widerstand [%]")
+plot.xlabel("Geschwindigkeit [km/h]")
+plot.legend(temps_list_leg)
+plot.grid()
+
+plot.figure()
+
+# Fd vs. velocity, param: car
+temp = 20
+vel_list = [20, 40, 60, 80, 100, 120, 130, 140, 160]
+car_list_leg = [f"{t['car']}" for t in car_list]
+
+rho_t = rho(temp)
+reference = fd(rho_t, 100, c_val_id3, area_id3)
+
+for car in car_list:
+	y_fd = []
+	for vel_kmh in vel_list:
+		fd_t = (fd(rho_t, vel_kmh, car['cw'], car['area'])/reference - 1) * 100
+		y_fd.append(fd_t)
+
+	plot.plot(vel_list, y_fd)
+
+plot.ylabel("Wind-Widerstand [%]")
+plot.xlabel("Geschwindigkeit [km/h]")
+plot.legend(car_list_leg)
+plot.grid()
+plot.show()
\ No newline at end of file