Data-assimilation closure for large-eddy simulation of quasi-geostrophic flow on the sphere

Sagy Ephrati, Arnout Franken, Erwin Luesink, Bernard Geurts

Published 2023-12-20Version 1

A closure model is presented for large-eddy simulation (LES) based on the three-dimensional variational data assimilation algorithm. The approach aims at reconstructing high-fidelity kinetic energy spectra in coarse numerical simulations by including feedback control to represent unresolved dynamics interactions in the flow as stochastic processes. The forcing uses statistics obtained from off-line high-fidelity data and requires only few parameters compared to the number of degrees of freedom of LES. This modeling strategy is applied to geostrophic turbulence on the sphere. It proves to accurately recover the energy spectra and zonal velocity profiles in the coarse model for three generic situations.