Resolvent4py: a parallel Python package for analysis, model reduction and control of large-scale linear systems

We introduce “Resolvent4py,” a parallel Python package for the analysis, model reduction and control of large-scale linear systems with millions or billions of degrees of freedom. This package provides the user with a friendly Python-like experience (akin to that of well-established libraries such as numpy and scipy) while enabling MPI-based parallelism through mpi4py, petsc4py and slepc4py. In turn, this allows for the development of streamlined and efficient Python code that can be used to solve and analyze interesting problems in fluid mechanics. Currently, the package includes state-of-the-art algorithms for linear stability and resolvent analyses of fluid flows around steady states, stability and harmonic resolvent analyses of flows around time-periodic base flows, and linear-time-invariant balanced truncation using frequential Gramians. The use of the package is demonstrated on several examples, including the Mach 7.7 flow over a 15 deg compression ramp and the Mach 5.9 flow over a 7 deg half-angle blunt cone.