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Chombo is provided as a fully open-source distribution.

This is a source code release. The 3.2 version of this software was released March 25. 2014, and the most recent patch (patch 6) was released on April 26, 2019 . We welcome feedback concerning this software to better meet your needs. Contact [email protected] with comments. We welcome nice things you have to say as well as criticism.

There is a Google group for general discussion among Chombo users, which you can find here:!forum/chombousers – you can also e-mail the users group at [email protected]

The current Chombo release is distributed via the svn version control system. Before you can download Chombo, you must register. Registration is free and does not carry an encumbrance on your part. We just need to keep a record of access. Registration gets you an account via which you can access the Chombo svn repository via svn. If you have already previously registered for Chombo download, you may skip directly to the download page.

  1. Register
  2. Download instructions

The #Design Docs for Chombo can be downloaded independently of the source and without registration.

Access to Chombo

Chombo 3.2 is now available. We are using an  SVN server, "", to provide access to all our releases. In order to download Chombo 3.2, go to "" and register. When you do this, you will be given details on how to access Chombo 3.2 (and previous versions) using SVN. Before (or after) you register, you can view this announcement, the release notes (see below), and the access instructions.

What is Chombo again?

  • The Chombo package provides a set of tools for implementing finite difference methods for the solution of partial differential equations on block-structured adaptively refined rectangular grids. Both elliptic and time-dependent modules are included. Support for parallel platforms and standardized self-describing file formats are included.
  • Chombo provides a distributed infrastructure for parallel calculations over block-structured, adaptively refined grids. Chombo's design is uniquely flexible and accessible. Any collaborator will be able to develop parallel applications to solve the partial differential equations in which she is interested with far shorter development times than would be possible without the infrastructure. Very careful design and documentation allows said collaborator to enter the software at many levels. She will be able to use Chombo to investigate deep technical issues of adaptive mesh refinement algorithms or to simply adapt the example applications to solve different scientific problems.
  • Chombo is built using a combination of C++ and Fortran and uses MPI message-passing for parallel execution. The code is simple to build by today's standards, using just regular GNU Make. It has been ported to several supercomputers and runs just fine on laptops and workstations and Macs.   

Contact info and email list

Chombo Development Team
Applied Numerical Algorithms Group
Lawrence Berkeley National Laboratory

Chombo 3.2 Release Notes

You can contact the Chombo development team at <[email protected]> and
the Chombo users e-mail group at <[email protected]>

- We have implemented interfaces to the PETSc solver library
  ( which generate matrices for discretizations
  on AMR hierachies of grids for use in PETSc solvers. This is useful for
  problems, such as those with geometrically complex material coefficients,
  in which our native geometric multigrid solvers are not efficient. An
  accompanying single-level interface is also useful as a bottom-solver for
  use with our geometric multigrid solvers. Details can be found in Chapter
  7 in doc/chomboDesign.pdf.

- Chombo has updated to use the HDF5 1.8 API, although support for the 1.6
  API is still in place for this release. This means (among other things)
  that the -DH5_USE_16_API compiler flag is no longer required.

- Hybrid parallelism is now possible in Chombo, the base classes have been
  made thread-safe. OpenMP is used in some of the library code including
  Godunov and Poisson solvers. Among the released examples AMRGodonov and
  AMRPoisson/exexCell can use OpenMP.

  Current status: There are several problems with the OpenMP implementation
  that are being corrected.  In a few weeks, corrections will be merged
  into the Chombo 3.2 release to make the OpenMP code fully functional.

- Embedded boundary generation has been optimized for run time, memory usage,
  and parallel load balancing. 

- We have added an embedded-boundary (EB) adaptive mesh refinement
  (AMR) compressible Navier-Stokes code in releasedExamples/EBAMRCNS.

- Also, as one might expect, this release contains many (well, not
  *that* many) bugfixes and minor capability upgrades over the 3.1

Chombo 3.1 Release Notes

It has been a long time. This is not a major feature upgrade of Chombo but this does contain many bug fixes from over the years.

  • The transition from OldAMRElliptic is complete and the OldAMRElliptic library no longer appears in the released code base.
  • We have moved to a new "releasedExamples" directory which contains (with cleaned up source code, input files, and GNUMakefiles) :
    • AMRPoisson
    • AMRGodunov
    • AMRINS
    • EBMenagerie
    • EBAMRPoisson
    • EBAMRGodunov
    • MultiDimPhase
  • Chombo can now be built inside a Chombo namespace. This can be helpful for people integrating their packages into larger software projects.
  • Chombo now has the capability (using namespaces and a moderately complex build process) to do mixed-dimensional problems. See the users guide and MultiDimPhase example for details.
  • Code which is dimension-independent has been removed from the BoxTools library and put into its own BaseTools library.
  • Documentation is now included inside the Chombo release itself (in the Chombo/doc directory).
  • Chombo is distributed through a branch of our Subversion revision control system instead of by tar files.
  • By popular demand, Chombo now includes tools to support AMR constrained transport schemes. We don't have an example using these tools but we now have several Chombo users of this capability so it is now available to all our users.
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