Large-eddy simulation of turbulent winds during the Fukushima Daiichi Nuclear Power Plant accident by coupling with a meso-scale meteorological simulation model

Abstract

Abstract. A significant amount of radioactive material was accidentally discharged into the atmosphere from the Fukushima Dai-ichi Nuclear Power Plant from 12 March 2011, which produced high contaminated areas over a wide region in Japan. In conducting regional-scale atmospheric dispersion simulations, the computerbased nuclear emergency response system WSPEEDI-II developed by Japan Atomic Energy Agency was used. Because this system is driven by a meso-scale meteorological (MM) model, it is difficult to reproduce smallscale wind fluctuations due to the effects of local terrain variability and buildings within a nuclear facility that are not explicitly represented in MM models. In this study, we propose a computational approach to couple an LES-based CFD model with a MM model for detailed simulations of turbulent winds with buoyancy effects under real meteorological conditions using turbulent inflow technique. Compared to the simple measurement data, especially, the 10 min averaged wind directions of the LES differ by more than 30 degrees during some period of time. However, distribution patterns of wind speeds, directions, and potential temperature are similar to the MM data. This implies that our coupling technique has potential performance to provide detailed data on contaminated area in the nuclear accidents.

Development of a Time–Height Profile Assimilation Technique for Large-Eddy Simulation

“…The overall goal of MMC is to create a new predictive numerical simulation capability that is able to represent the full range of atmospheric flow conditions, to gain physical insights into complex fluid dynamics, and improve low-fidelity models and parametrizations. Applications of MMC are numerous and include urban meteorology (Baklanov and Nuterman 2009;Liu et al 2012), pollutant dispersion (Nakayama et al 2015), wildfire behaviour (Mandel et al 2011), atmospheric two-phase flows such as snow transport (Vionnet et al 2017), and wind-energy applications (Sanz Rodrigo et al 2017a).…”

Acceleration of Wind Simulation Using Locally Mesh-Refined Lattice Boltzmann Method on GPU-Rich Supercomputers

“…Since air flows behave as almost incompressible fluids, CFD simulations based on an incompressible Navier-Stokes equation are widely developed. The LOcal-scale High-resolution atmospheric DIspersion Model using Large-Eddy Simulation (LOHDIM-LES [1]) has been developed in Japan atomic energy agency (JAEA). The LOHDIM-LES can solve turbulent wind simulation with Reynolds numbers of several million.…”