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Simulations in the Natural Sciences I

ESC201:Fall 2021: Monday Lecture: 13:00-14:00 Exercises: 14:00-17:00 in online only

TAs: Stefan Schafroth, Sebastian Schulz (, Noah Kubli (

Corona Virus Measures

Dear Students,

Video lectures will be available (see below).

Exercises will take place via Microsoft Teams :ESC 201

Joachim Stadel

Video Lectures

Videos for the lectures can be found here (they are too large for my Wiki):

ESC201 Video downloads



Your solutions should be handed in 13 days after each assignment has been given, i.e. Sunday night by 21:00 two weeks after the Monday lecture. Assignments should be individual and should be in python and provide a correct virtual environment! (if you stick to standard libraries like numpy, matplotlib, scipy… you can also just submit your python source code together with the output of your program)

For help getting started with virtual environments, please read carefully Python Virtual Environments for Pip and Python Virtual Environments for Conda.

You should email 3 things to Sebastian (

  1. The working python source code
  2. The requirements.txt file for your virtual environment (if you used a virtual environment)
  3. A .pdf or .png image or animation of the output of your program



Please add the names of the people you work together (if you do) to the comment section of your python scripts.

Create a virtual environment using


- run virtualenv yourenv_name to create a virtual environment

- run source yourenv_name/bin/activate to activate yourenv_name

- install necessary libraries that you want using pip install package_name

- work in that directory, get your outputs (*.pdf, *.png, *jpeg, *.mp4, etc…)

- run pip freeze > requirements.txt to get your list of libraries


- run conda create -n yourenvname python=x.x anaconda to create a virtual environment

- run source activate yourenvname to activate yourenv_name

- install necessary libraries that you want using conda install -n yourenv_name package_name

- work in that directory, get your outputs (*.pdf, *.png, *jpeg, *.mp4, etc…)

- run conda list –export > requirements.txt to get your list of libraries

List of assignments

  1. Implement the bisection root finding method presented in the first lecture for a function f of your choice (e.g. f(x) = ax³ + bx² + cx + d, or xx - 100 = 0)! (to submit by 3 October 20201, 9pm)
  2. Plot (and/or animate) the elliptical orbit of a planet around the sun by repeatedly solving Kepler's equation with Newton's method (or the bisection method), as explained in the lecture! (to submit by 10 October 2021, 9pm)
  3. Draw a Feigenbaum diagram that results from solving the logistic equation (to submit by 17 October, 2021, 9pm). (Optional: Implement a function that allows you to zoom into the Feigenbaum diagram)
  4. Fractals: Draw some Julia sets with various constants c (you can start with the Mandelbrot set as it was explained in the lecture and the exercise class)! (to submit by 24 October, 2021, 9pm)
  5. Ordinary Differential Equations: Solve the Lotka-Volterra equation using the Euler method and the midpoint Runge-Kutta method (optional: 4th order Runge Kutta method) and compare the results. Make two plots: the time dependence of both populations (mice and foxes), and the phase diagram using different initial conditions (to submit by 31 October, 2021, 9pm).
  6. Symplectic Integrators: Use the Leap-Frog method to make a phase plot (p vs q) of the harmonic oscillator for different total energies. Compare the results with what you get using the Forward Euler method and the midpoint Runge-Kutta method. Make the same plot for a simple pendulum (to submit by 7 November, 2021, 9pm).
  7. Make a solar system orrery following the steps outlined in the lecture (to submit by 14 November, 2021, 9pm)!
  8. Elliptical partial differential equations: Solve the Poisson equation for the electromagnetic potential using the SOR method described in the lecture, with boundary conditions given by a 1000 Volt stick in the center of a 0 Volt box (as depicted in the lecture notes). Plot the contours of the resulting potential (to submit by 21 November, 2021, 9pm).
  9. Interpolation, Part 1: Trace the movement of electrons in an electromagnetic potential (e.g. the one from the last exercise) with Leapfrog or Runge-Kutta. Use bilinear or bicubic interpolation for the potential. (not graded, to submit by 28 November, 2021, 9pm).
  10. Interpolation, Part 2 (WIN A PRIZE): Design an optimal electron detector (specifics in lecture materials) (to submit by 5 December, 2021, 9pm).
  11. Hyperbolic PDEs: Solve the linear advection equation by evolving an initial waveform in a periodic grid. See how the waveform behaves after passing through the grid multiple times and compare the results you get when using various methods introduced in the lecture (e.g. the LAX method, upwind scheme, LAX-Wendroff method…) (you can get 0.5 bonus points if you implement all three variants provided in Stefan's Hyperbolic Hints.txt) (to submit by 12 December, 2021, 9pm).
  12. 2D advection: Solve the 2D advection problem using two methods introduced in the lecture (CIR and CTU) and compare if and how your solution diffuses numerically (to submit by 19 December, 2021, 9pm).
  13. Optional (grade for this exercise can replace your worst grade so far): 1D Hydrodynamics: Solve the “shock tube” problem and the Sedov-Taylor blast wave using the three methods provided in the lecture (detailed assignment can be found in the lecture notes) (to submit by 19 December, 2021, 9pm ).
spin/esc201_hs2021.txt · Last modified: 2021/12/13 14:18 by sebastian