Numerical time domain simulations have proven applicable for analysing marine systems and operations, but available tools often target specific sub-problems or applications associated with a system or an operation. Such tools are also often limited in terms of extensions and usage. This has motivated the development of FhSim at SINTEF Fisheries and Aquaculture (SFA). FhSim is a software framework aimed at simulating especially marine systems in the time domain, using models described as ordinary differential equations (ODEs).
In this paper, we present the architecture and core functionality of the FhSim framework, including modelling, integration and 3D-visualisation. We also present a series of simulation cases which illustrate the different core properties of FhSim, including numerical simulations of aquaculture structures, model-based estimation of trawl nets and optimisation of energy systems in ships.