CFD's Carbon Footprint in 2022

Contemporary fluid dynamics simulations leverage growing computational resources and consequently enable direct simulation at increasing flow Reynolds number. However, electricity needed to power these computers, when derived from non-renewable sources yields carbon production. A recent analysis suggested that the carbon footprint of a direct simulation grows with nearly the fourth power of the Reynolds number. This work leverages that analysis and considers a larger database of simulations. A set of simulations from 2022 is considered to construct a sample distribution of fielded simulation Reynolds numbers. We develop confidence intervals to determine a typical Reynolds number simulated and, using the previously derived correlation for carbon footprint, we estimate the average carbon footprint for a direct simulation in 2022. The distribution and total carbon footprint of the database is considered and we conclude with an extrapolation for total carbon footprint of CFD in 2022. The goal of this work is that better quantitative assessment of CFD’s contribution to climate change may influence modelling choices such as the Reynolds number considered, modelling paradigm, location of computing resources, and choice of research problem.