Energy Transfer and Scale Dynamics in 2D and 3D Laser Driven Jets*

We demonstrate a methodology for diagnosing the multiscale dynamics and energy transfer in complex HED flows. The approach separates incompressible, compressible, and baropycnal contributions to energy scale-transfer and quantifies the direction of these transfers in (generalized) wavenumber space. By comparing the kinetic energy (KE) transfer across scales in simulations of 2D axisymmetric versus fully 3D laser driven plasma jets, we find the 2D modeling suffers from significant spurious energization of the bulk flow by a turbulent upscale cascade. A coherent circulation that arises near the jet's leading edge in 2D but absent in 3D helps propel the axisymmetric jet farther (approximately 25% by 3.5 ns) and helps keep it collimated. The methodology may help with inter-model comparison and validation, including future modeling efforts to alleviate some of the 2D hydrodynamic artefacts in HED simulations like astrophysics and inertial confinement fusion (ICF), which are costly to model in 3D.