Merging of zonal flows in gyrofluid resistive drift-wave turbulence

Non-linear dynamics of zonal flows are investigated in the context of the gyrofluid modified Hasegawa–Wakatani model. Merging of zonal flows and the chaotic development of the initial zonal flow pattern is explored. Conservation equations for zonal flow momentum and energy with consistent finite Larmor radius effects are derived and used for a quantitative analysis of zonal flow mergers in numerical simulations. The nonlinear local Reynolds stress transfer as opposed to (hyper)viscous dissipation is found to be the main cause of merging.