A framework for efficient reduced order modelling in the Julia programming language

In this paper we propose ROManifolds, a Julia-based package geared towards the numerical approximation of parameterized partial differential equations (PDEs) with a rich set of linear reduced order models (ROMs). The library favors extendibility and productivity, thanks to an expressive high level API, and the efficiency attained by the Julia just-in-time compiler. The implementation of the package is PDE agnostic, meaning that the same code can be used to solve a wide range of equations, including linear, nonlinear, single-field, multi-field, steady and unsteady problems. We highlight the main innovations of ROManifolds, we detail its implementation principles, we introduce its building blocks by providing usage examples, and we solve a fluid dynamics problem described by the Navier-Stokes equations in a 3d geometry.