The STG (for

Soria Trias Gorobets, main
developers of the code) is a dedicated code for large-scale
simulations of incompressible turbulent flows in rectangular domains
with one periodic direction. The core of the code is the

highly-scalable hybrid direct-iterative Krylov–Schur–Fourier
Decomposition (KSFD) Poisson solver [5] that has been designed and
optimized for this particular domain configuration. This solver is
among the world's faster flow solvers for this certain kind of
applications. The numerical algorithm of the code is based on a

fully
conservative staggered fourth-order symmetry-preserving discretization [1] that provides
high accuracy and unconditional stability for time-accurate
simulations. Moreover, a

fully explicit self-adaptive time integration scheme [12] is used; compared with the classical CFL condition it significanly improves the efficiency of the time integration.