This is the astro-ph blog of the Theoretical Modelling of Cosmic Structures group (TMoX) at the Max-Planck-Institute for Extraterrestrial Physics. We are an independent Max-Planck Research Group focusing on the various aspects in the formation and evolution of galaxies. Part of our focus is on the formation and evolution of early-type galaxies, super-massive black holes, the formation of the first structures in the universe and the enrichment history of the Universe. We are theoreticians using analytic modelling as well as numerical simulations in our work.

The CosmologyCake blog is dedicated to the discussion of research papers and current developments. We will regularly post interesting papers and comment on them. Feel free to leave your comments as well. We encourage authors of discussed papers to post replies if they wish to. Our aim is to provide a platform to discuss recent astro-ph papers within a wider audience. Please feel free to send papers you would like to be discussed to us at

1 March 2012

A Density Independent Formulation of SHP

Authors: Saitoh & Makino
Link: here

A new SPH scheme is presented in this paper. The scheme is based on using the total internal energy density as smoothed quantity. This allows for a formulation of conservation equations that are independent from the gas density. The advantage is that pressure is naturally treated as a smoothed quantity, solving the well known problems of SPH in resolving contact discontinuity. The new implementation has been successful in several standard tests.

1 comment:

  1. There are two points that are not clear to me:

    1) SPH is based on constant mass, while the total internal energy used here can vary. That possibly implies a correction to the Euler equations.

    2) The sound speed cannot be derived from smoothed quantities, unless density is used.