Wengen 2: Cloud collision test, unequal masses



A high speed collision between two gas spheres where one of the impacting spheres is 1/20th of the mass of the other. The spheres have a temperature profile so that they are in gravitational equilibrium with their NFW density profiles.

Included physics

Hydrodynamical test that can be run with and without self-gravity of the gas. The results with and without gravity are quite different.


Tests ram-pressure and viscous stripping.

Analytical solution

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Publications using this test

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Useful references

Relevant background reading, or similar tests to be referenced here. This can also cross-reference other pages within this wiki.

Details of setup

Units and constants

See unit description for the Wengen 3 test.

Initial Conditions

NB: The smaller impacting sphere is a rescaled version of the larger sphere. The mass ratio between the SPH particles in the small to large sphere is 2:1. Change if necessary. Initial separation and velocity are 500kpc and -600km/s.


Add the initial conditions files here. Please make sure that your file format is described in File Formats.

Grid Resolution SPH Resolution
Low-res wengen2.low.h5 128x128x128 wengen2.low.std ~110k part
Med-res wengen2.med.h5 256x256x256 wengen2.med.std ~2e6 part
Hi-res wengen2.hi.h5 512x512x512 wengen2.hi.std -

It would be good to always add the following: Please see File Formats for a description of the above file formats and a collection of conversion tools.

How to analyse the test?

Describe here how the test is analysed and how it can be compared with results from other simulations, or to analytic results. It would be helpful to include a link to the analysis software used. It would be good to always add the following: Please see Analysis Tools to obtain the above analysis tools.


List here some example results from the test and describe their implications. Typically this will mean posting a couple of results figures.

Tests run so far

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Code Person Publication
The Template Test: myfavecode Bob

Discussion forum for this test

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