NekBox is a version of Nek5000 specialized to box geometries and intended for prototyping new methods.

• Box geometry (mesh corners are a global tensor product)
• Only P, W, O, v, or SYM velocity boundaries
• Only P, I, or T thermal boundaries
• Only PN-PN
• Only 1 scalar
• Probably some more

• 2x less memory used, all dynamically allocated
• Spectral coarse solver for uniform meshes (very fast)
• No re2 or map files
• O(minute) startup
• Pure Fortran90 (including usr file)
• 2x smaller codebase

NekBox uses makenek and rea files just like Nek5000. The rea files don't need to include mesh information (never any re2 files). The usr file is compiled in just like in Nek5000, but is written in Fortran90 and references modules instead of common blocks. There is no map file.

It is highly recommended to setup NekBox runs using genrun script.

The most reliable examples are those used by Travis for continuous integration. Just pick a TEST_SUITE from travis and follow the instructions there.