Ensemble turbulence experiments in the HED regime

Hydrodynamic instabilities are ubiquitous on interfaces that interact with shocks. These instabilities are often seeded by surface roughness that is too computationally expensive to resolve directly. Furthermore, the instability growth is often initially laminar, so that the best way to initialize sub-grid turbulence models (such as LANL’s BHR) isn’t readily apparent. Recent campaigns in the HED regime have used spanwise spatial lineout averaging when calculating turbulence quantities such as “b”, the density-specific volume covariance. Most turbulence models are validated against fully developed turbulence and thus insensitive to the type of averaging used. However, during the transition to turbulence the type of averaging used may be an important consideration when comparing experiments to turbulence models. Here, we will present Omega-EP experiments in which a nominally identical single mode perturbation (up to surface roughness), heavy-to-light, RM with delayed onset RT experiment was repeated multiple times to generate an ensemble dataset, over which ensemble averaging may be used to calculate 2D distributions of turbulence quantities. A related talk by S. Pellone will discuss 3D simulations initialized based on detailed pre-shot characterizations of interface perturbations.