T5: Supernova explosion:
simulating a blast wave

Before the tutorials:

Think about:

• What happens when a star explodes?
• How does a setup to simulate this would look like?
• Re-think the general solution we had in the lectures!

During the tutorials:

You can run the experiments of a blast wave (as discussed in the lecture).

A simple blast wave

• Create a 3D grid with uniform distribution (say, 100×100×100) and a certain density (say 0.125).
  Do not forget how last time we used a glass to construct an other geometry from it!
• Assume low pressure (say 1e-20) and zero velocities.
• Give a handful of particles in the central part a very large pressure (say 1).
  Think about how to select the particles and what could be important here?
• When compiling the code, do not forget to enable NOGRAVITY and PERIODIC and to switch off LONG_X, LONG_Y and LONG_Z as you now deal with a cubic setup.
• Now choose a proper end time and spacing of the snapshots in the box.param. Also set a useful value for ArtBulkViscConst. As it is a strong shock, maybe start wit a value like 1.5.

Now we can perform the simulation and analyze it.

• Try to explain what is happening in the simulation?
• Can you indicate in the plots what would be the expected solution?
• Have you checked the geometry of how you deployed the energy? What should you check there?
• Try to have a look at the temperature of the gas.
• How would the results look like if we set a smaller value for ArtBulkViscConst as last time ?

Solutions

A simple example

• some example initial conditions to start with:
  wget https://www.usm.uni-muenchen.de/~dolag/Lille2026/T05/box.ic
• As the simulation this time takes quite a while, you can download one example snap file to start to do the analysis:
  wget https://www.usm.uni-muenchen.de/~dolag/Lille2026/T05/snap_010

Setup your own initial conditions

• Again, extending previous setup script, we can first create a 100×100×100 cube and then dump enormous energy in the center.
  • wget https://www.usm.uni-muenchen.de/~dolag/Hydro/Hydro/glass_10x10x10
  • wget https://www.usm.uni-muenchen.de/~dolag/Hydro/Hydro/Python/ic_header
    (if not already done before)
  • wget https://www.usm.uni-muenchen.de/~dolag/Lille2026/T05/setup_blast_3D.py
  • python3 setup_blast.py
• You should now have a setup which looks like the following, where wqe highlighted the box center and the particles which get initially the large pressure.
  

Example for analyzing the simulation

• Again, modify your plotting scripts from previous tutorials
• Remember the solutions for the problem we discussed in the lectures (scalings with time!)
• How can you overplot them in the time evolution?
  • wget https://www.usm.uni-muenchen.de/~dolag/Lille2026/T05/show_blast.py
  • python3 show_blast.py
• You should be able to obtain an animation like this and identify all the phenomena discussed in the lectures:
  

Useful commands

• More informations on the OpenGadget3 containers
• Start your docker session:docker run -it -v :/mnt --name opengadget3_container opengadget3:XXX
• Connect from a second shell to a running docker session:docker exec -it opengadget3_container bash
• Get the simulation code:cp -r ~/OpenGadget3 .
• Copy the config file: wget https://www.usm.uni-muenchen.de/~dolag/Hydro/Hydro/Config.sh
• Copy the parameter file: wget https://www.usm.uni-muenchen.de/~dolag/Hydro/Hydro/box.param
• Setup the environment for compiling the code: source Build/Container_build.sh
• Compile the code: make -j
• Run a simulation: mpiexec -np 2 OpenGadget3/OpenGadget3 box.param