update readme

.gitignore

@@ -0,0 +1,2 @@
+# pychage folders
+*.pyc

README.md

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-# ornithopter-airfoil-sim
-Simulation of an oscillating airfoil 
+# Ornithopter airfoil simulator
+
+This program calculates the motion of an airfoil attached to an ornithopter wing. The airfoil undergoes a sinusoidal oscillation and its angle is found through a torque balance. With this angle, the lift and thrust of the airfoil are calculated along with their mean values. It is assumed the airfoil is subject to the inertial reaction of its mass, an aerodynamic force, and a damped angular spring. Each of these forces/torques can be adjusted along with the amplitude and frequency of the oscillation. Therefore, it is possible to try out different constraints and observe how they affect lift and thrust.  
+
+### Requirements
+The scripts were written in [Python 3.9.5](https://www.python.org/downloads/) and require the following libraries: 
+- [numpy](https://numpy.org/install/)
+- [scipy](https://scipy.org/install/)
+- [matplotlib](https://matplotlib.org/stable/users/installing/index.html) 
+
+### How to use
+To execute the program, open the terminal/command prompt and browse to the folder containing main.py and run the command:  
+```
+>> python3 main.py
+```
+If you are using windows, you can simply double click interface.py and to open it with [IDLE](https://docs.python.org/3/library/idle.html). 
+
+To adjust the calculations, open input_parameters.py with a text editor and change the variables.
+
+### Sample output
+
+![image](figures/airfoil_motion.gif)
+
+![image](figures/mean_force.jpg)

input_parameters.py

@@ -1,27 +1,27 @@
 # aerodynamics
-COEF_AERO    = 1.5           # aerodynamic force scale
+COEF_AERO    = 1             # aerodynamic force scale
 VEL_INF      = 1             # velocity of incoming flow
 CHORD        = 1             # airfoil chord
 COEF_AERO   *= VEL_INF**2
 
 # mass parameters
 MASS_POS     = -0.5          # position of center of mass
-MASS         = 0.3           # mass of airfoil
+MASS         = 0.1           # mass of airfoil
 INERTIA      = MASS*( (CHORD**2)/12 + MASS_POS**2 )   # assume airfoil is thin rod
 
 # oscillation
 AMPLITUDE    = 1             # amplitude of oscillation
-ANG_FREQ     = 0.8           # angular frequency of oscillation
+ANG_FREQ     = 1             # angular frequency of oscillation
 
 # angular spring
 COEF_SPRING  = 0.2           # angular spring/elastic constant
 COEF_DAMPING = 0.1           # angular damping constant
-ANGLE_BIAS   = 0.4           # angle offset in rest point of angular spring
+ANGLE_BIAS   = 0.5           # angle offset in rest point of angular spring
 
 # animation
 TIME_MAX     = 40            # maximum time value for simulation
 FRAME_TIME   = 50            # frame delay in milliseconds
-SAVE_FIGURES = False         # save animation as .gif and plot as .jpg
+SAVE_FIGURES = True          # save animation as .gif and plot as .jpg
 
 # axis bounds
 XLIM         = 1.5

main.py

@@ -228,8 +228,8 @@ def solveSystem():
 
 # 3. display
 if SAVE_FIGURES:
-	anim.save("airfoil_motion.gif", writer=animation.PillowWriter(fps=10), dpi=100 ) 
-	figure1.savefig('mean_force.jpg')
+	anim.save("figures/airfoil_motion.gif", writer=animation.PillowWriter(fps=10), dpi=100 ) 
+	figure1.savefig('figures/mean_force.jpg')
 
 plt.tight_layout()
 plt.show()