Solenoidal force balances in numerical dynamos

Numerical simulations of the geodynamo (and other planetary dynamos) have made significant progress in recent years. As computing power has advanced, some new models claim to be ever more appropriate for understanding Earth's core dynamics. One measure success such is ability replicate expected balance between forces operating within core; Coriolis and Lorentz are predicted most important. The picture complicated an incompressible flow by existence pressure gradient force which renders parts all dynamically unimportant. This can confuse situation, especially when scale dependence considered. In this work we investigate balances through alternative approach eliminating each form ‘solenoidal balances’. We perform a length-scale-dependent analysis several spherical find that removal offers compared with looking at traditional alone. Solenoidal provide agreement results previous studies but also differences. They offer cleaner overall dynamics introduce differences smaller scales. implications purporting reached Earth-like regimes: order achieve meaningful comparison forces, only solenoidal part should