Stardis The Monte Carlo framework for coupled thermal problems

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Stardis is a thermal simulation framework for complex 2D and 3D environments, based on new Monte Carlo algorithms built from reformulations of the main heat transfer phenomena: conduction, convection and radiation. A set of cross-recursive algorithms have then been derived, and result in the simulation of "thermal paths" that explore space and time until a boundary condition or an initial condition is found. The key concept here is that heat transfer phenomena are not considered separately but are naturally coupled via the cross-recursion of the various Monte Carlo algorithms.

Refer to the Stardis consortium's service offer for long-term advices on its use, contribute to orientation choices and interact with its developers and other users.

Beyond its use as a regular thermal simulation tool, the Stardis framework explicitly targets engineers, researcher, teachers or students wishing to fully appropriate the statistical formulation of heat transfer, from theoretical concepts to practical implementation. The complete Stardis framework is thus released under free licenses that guarantee the users the ability to freely use, study, modify or extend the complete source code according to their needs.

Despite its specific advantages, Stardis is not meant to fully replace already well established and highly validated thermal simulation tools. Instead, it can be seen as an additional tool that can be useful for various purposes:

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The Stardis framework is structured around two main components. The first one, Stardis-Solver, is the core library that implements the Monte Carlo algorithms. The second one is the Stardis application, a command line tool that can be seen as a reference implementation of a complete workflow relying on Stardis-Solver, from input data describing the system to simulate (geometry, thermal properties, limit conditions, etc.) to heat transfer simulation and results post-processing. See below for more information on each of these components.


Infrared timelapse animation of a chip and its heatsink covering a 14-second period of time. Computed using the stardis infrared rendering feature, one image per simulated second. Acknowledgment to Léa Penazzi and Anne Castelan for the scene geometry (also available in Stardis: Starter Pack) actually used in an upcoming research article, and to Simon Eibner who computed the animation.

Stardis-Solver is the core library of Stardis: it simulates coupled convecto - conducto - radiative heat transfers by sampling thermal paths that explore space and time until a boundary condition or an initial condition is met. Note that this path formulation does not require any volumetric mesh: in addition of the thermal properties and the limit/boundary conditions, only the geometry defining the contours of the objects is necessary.

The Stardis-Solver library is currently used in the two following projects:

The coupled Monte Carlo algorithms implemented into Stardis-Solver are based on the following hypothesis:

Stardis computation time as function of geometrical refinement. Both the standard Monte Carlo computation and the Green function construction and usage are insensitive. In this example, once constructed, using the Green function with any new set of sources is 103 times faster than Monte Carlo.

The main functionalities provided by Stardis-Solver upon the aforementioned hypothesis are as follows:

step sin pulse
Temporal dynamics analysis of a solid cube which has temperatures imposed on its left and right sides, and has adiabatic boundaries elsewhere. The center temperature is the result of a simple postprocess of a single Monte Carlo computation.

Stardis CLI tools

The stardis framework includes Command Line Interface (CLI) software, namely stardis and sgreen, to use along with Stardis-Solver. They make it easy to exploit the features of the solver.


The installation of Stardis consists of compiling the solver and the command line tools directly on the target machine. A simple way is to rely on star-build, which automates the build and installation of stardis and its dependencies from source code.


To build stardis with star-build, first make sure your system has the following prerequisites:


Assuming that the aforementioned prerequisites are available, the build procedure is summed up to:

~ $ git clone
~ $ cd star-build
~/star-build $ make PREFIX=~/stardis BUILD=src/

With PREFIX defining the path where Stardis will be installed and BUILD defining the installation script to be run.

By default, Stardis is built with MPI enabled, so OpenMPI is one of its requirements. To disable MPI support, simply set the DISTRIB_PARALLELISM parameter to NONE as follows:

~/star-build $ make \
  PREFIX=~/stardis \


Evaluate the installed stardis.profile file in the current shell to register htrdr against it. You can then run stardis and consult its manual pages:

~ $ . ~/stardis/local/etc/stardis.profile
~ $ stardis -h
~ $ man stardis

Refer to the Stardis: Starter Pack to quickly run a thermal simulation through the stardis CLI; this archive provides input data and scripts and is a good starting point to begin with the Stardis framework.


Stardis is free software released under the GPLv3+ license: GNU GPL version 3 or later. You can freely study, modify or extend it. You are also welcome to redistribute it under certain conditions; refer to the license for details.