Application of immersed boundary method for jet flow in grating type structure

グレーチング構造中のジェット流れへの境界埋め込み法の適用

廣瀬 意育  ; 石垣 将宏 ; 安部 諭  ; 柴本 泰照 

Hirose, Yoshiyasu; Ishigaki, Masahiro; Abe, Satoshi; Shibamoto, Yasuteru

This paper describes an application of an immersed boundary method (IBM) to internal structure in a containment vessel as a means to reduce the modeling cost for accident analysis. A brinkman penalization method, that is one of the IBMs, is selected and implemented in OpenFOAM code. The calculation is performed for a grating-type structure in a rectangular vessel and an upward jet flow impinging on the grating is analyzed. The IBM is an appealing approach for solving flow passing complex geometry, whereas a very complicated body fitted mesh with fine resolution might be required in a conventional CFD approach. The results were compared with experimental data of flow velocity distribution through the grating measured by Particle Image Velocimetry technique. The flow immediately downstream of the grating is characterized by multimodal profile with intervals determined by a lattice width of the grating. This multimodal flow merges into one with unimodal shape in the downstream far from the grating. The present analysis reproduced the distinctive flow structure observed in the experiment. The model predicted a serrated profile consistent with the experimental results and this could be reproduced even with a relatively regular computational mesh compared to the traditional method.