[3P08-13] Accident Analysis

3:45 PM - 4:00 PM JST(6:45 AM - 7:00 AM UTC)

[3P12] Application of Data Assimilation to Flow Analysis of a Jet into a Density Stratified Layer

*Takayuki Wada¹, Masahiro Ishigaki¹, Yoshiyasu Hirose² (1. Univ. of Fukui, 2. JAEA)

Keywords:

data assimilation,local ensemble transform Kalman filter,computational fluid dynamics,density stratification

In a severe accident, three-dimensional fluid behavior dominates inside the containment vessel, and CFD is effective for analysis. This study aims to clarify conditions for improving analysis accuracy by applying data assimilation to CFD analysis of jet flows. A jet penetrating a density-stratified cylindrical vessel was analyzed using a twin experiment with the Local Ensemble Transform Kalman Filter. Velocity, temperature, and helium mass fraction were used as observational data. Uniformly distributed observation points improved gas concentration analysis, and increasing point density near the jet improved velocity field accuracy. Results showed that observation point distribution has a decisive impact on assimilation performance. This research was supported by JSPS KAKENHI Grant Number JP23K04629.