openCFS: An open-source finite-element software for advanced multiphysics simulations

Abstract

The software openCFS (formerly “CFS++”) is an open-source finite-element software designed for coupled field simulations including electromagnetics, acoustics, linearized fluid flow, solid mechanics, and heat transfer. It combines a modular C++ core with a declarative XML modeling language and a Python automation layer (pyCFS). Besides standard formulations, openCFS provides advanced capabilities such as time-domain equivalent-fluid modeling for dispersive porous materials, thermoviscous/viscous acoustics with Maxwell slip boundary conditions on moving domains, advanced vector hysteresis models in electromagnetics, and robust treatment of non-conforming and rotating interfaces, complemented by density-based and feature-mapping topology optimization. Development follows modern software-engineering practice, with continuous integration and more than 600 automated tests across platforms. This article describes the architecture, workflow, and key features, and demonstrates them on representative applications.