# Fluidsim documentation¶

Fluidsim is a framework for studying fluid dynamics with numerical simulations using Python. It is part of the wider project FluidDyn.

Fluidsim is an object-oriented library to develop solvers (mainly using pseudo-spectral methods) by writing mainly Python code. The result is very efficient even compared to a pure Fortran or C++ code since the time-consuming tasks are performed by optimized compiled functions.

Fluidsim is a HPC code written mostly in Python. It uses the library fluidfft to use very efficient FFT libraries. Fluidfft is written in C++, Cython and Python. Fluidfft and fluidsim take advantage of Pythran, a new static Python compiler which produces very efficient binaries by compiling Python via C++11.

An advantage of a CFD code written mostly in Python is that to run simulations and analyze the results, the users communicate (possibly interactively) together and with the machine with Python, which is nowadays among the best languages to do these tasks. Moreover, it is much simpler and faster than with pure Fortran or C++ codes to add any complicate analysis or to write a modified solver.

We have created fluidsim to be easy and nice to use and to develop, efficient and robust.

Fluidsim is a young package but the list of solvers already implemented (see fluidsim.solvers) gives a good idea of the versatility of this framework. However, currently, fluidsim excels in particular in solving equations over a two-dimensional periodic space:

• Incompressible Navier-Stokes equations,
• Incompressible Navier-Stokes equations under the Boussinesq approximation (with a buoyancy variable),
• Stratified Navier-Stokes equations under the Boussinesq approximation with constant Brunt-Väisälä frequency,
• One-layer shallow-water equations + modified versions of these equations,
• Föppl-von Kármán equations (elastic thin plate).

## Modules Reference¶

 fluidsim.base Base classes for writing solvers =================================== fluidsim.operators Numerical operators ====================== fluidsim.solvers Solvers for a variety of physical problems ============================================= fluidsim.util Utilities for FluidSim =========================