Numerical Simulation of the Acoustical Propagation of Thunder


Previous models for generating synthetic thunder lacked wave interaction due to lightning channel tortuosity. In this work, a two-dimensional CFD model based on the Navier-Stokes equations is selected for utilization. This model includes the effects of shear viscosity, bulk viscosity, thermal conductivity, wind shear, refraction, and is capable of applying the effect of dispersion due to molecular relaxation of nitrogen and oxygen. The model is numerically solved using a hybrid of schemes in space for the purpose of both stability and efficiency, and a Runge-Kutta scheme used in time. The technique of adaptive mesh refinement (AMR) is implemented through the Structured Adaptive Mesh Refinement Application Infrastructure (SAMRAI) developed by Lawrence Livermore National Laboratory. To insert the complex geometry of a lightning channel source, a combination of mathematical functions is developed to allow the source to be sufficiently smooth at arbitrary resolutions for stability. The final result is a physically-based model capable of running on a large-scale parallel platform that can reproduce the acoustic signature of arbitrary tortuous lightning channel geometries while including the effects of wave interaction.

Feb 14, 2017 3:30 PM — 4:30 PM
Bechtel Collaboratory, Discovery Learning Center
Engineering Center, University of Colorado at Boulder, Boulder, CO 80309

National Renewable Energy Laboratory