An investigation of the self-transition to turbulence by buoyancy force using compressible direct numerical simulation

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K14890
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Kobe University
• Principal Investigator: Li ChungGang 神戸大学, システム情報学研究科, 講師 (70650638)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: unstable phenomena / natural convection / turbulence

Outline of Final Research Achievements

The unstable phenomena induced by the natural convection in an open-ended vertical channel with hot-cold wall configuration are investigated. To accurately perform the simulation, a modified compressible solver, which can deal with the buoyancy-induced turbulence, has been developed. The solver can appropriately control the dissipation as an implicit turbulence model to have a more accurate result. The simulation result shows that the existing empirical experience for the natural convection in a vertical channel cannot be applied here. To better reflect the underlying physics, Grossmann-Lohse theory, originally proposed of horizontal (Rayleigh-Benard) convection, is applied to describe the flow field and the scale analysis for the flow characteristics near the wall is also performed. The coexisted flow field of the laminar and turbulence are observed. The above research result has been applied for the simulation of the natural convection with 3D random roughness elements.

Free Research Field

熱流体解析

Academic Significance and Societal Importance of the Research Achievements

垂直チャネルの高温と低温壁面についての設置は様々な日常生活の応用がある。例えば、壁掛け式パネルヒーター。計算と数値方法の制限のため、このような研究はまだされていないである。以上の課題を解決するため、高精度な計算方法を開発し、シミュレーションをした。この結果より、従来の法則を適用できないことが示す。さらに、新しい不安定的な熱流体の相互作用現象を解明する。未来に、ヒーターとエネルギー節約に関する課題を貢献することを期待される。