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RISS 인기검색어
- 검색키워드
- 저자 : Jinquan Cheng (검색결과 3 건)
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Stabilized finite element technique and its application for turbulent flow with high Reynolds number
Cheng Huang,Bao Yan,Jinquan Xu,Dai Zhou 한국풍공학회 2011 Wind and Structures, An International Journal (WAS Vol.14 No.5
In this paper, a stabilized large eddy simulation technique is developed to predict turbulent flow with high Reynolds number. Streamline Upwind Petrov-Galerkin (SUPG) stabilized method and three-step technique are both implemented for the finite element formulation of Smagorinsky sub-grid scale (SGS) model. Temporal discretization is performed using three-step technique with viscous term treated implicitly. And the pressure is computed from Poisson equation derived from the incompressible condition. Then two numerical examples of turbulent flow with high Reynolds number are discussed. One is lid driven flow at Re = 10^5 in a triangular cavity, the other is turbulent flow past a square cylinder at Re = 22000. Results show that the present technique can effectively suppress the instabilities of turbulent flow caused by traditional FEM and well predict the unsteady flow even with coarse mesh.
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Stabilized finite element technique and its application for turbulent flow with high Reynolds number
Huang, Cheng,Yan, Bao,Zhou, Dai,Xu, Jinquan Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.5
In this paper, a stabilized large eddy simulation technique is developed to predict turbulent flow with high Reynolds number. Streamline Upwind Petrov-Galerkin (SUPG) stabilized method and three-step technique are both implemented for the finite element formulation of Smagorinsky sub-grid scale (SGS) model. Temporal discretization is performed using three-step technique with viscous term treated implicitly. And the pressure is computed from Poisson equation derived from the incompressible condition. Then two numerical examples of turbulent flow with high Reynolds number are discussed. One is lid driven flow at Re = $10^5$ in a triangular cavity, the other is turbulent flow past a square cylinder at Re = 22000. Results show that the present technique can effectively suppress the instabilities of turbulent flow caused by traditional FEM and well predict the unsteady flow even with coarse mesh.
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Bandar AlMangour,Jinquan Cheng,Dariusz Grzesiak,Yu‑Jin Hwang,Kee‑Ahn Lee 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2
The low density and high biocompatibility of Mg-based materials make them suitable for lightweight structural and biomedicalapplications. In this study, we explored the use of selective laser melting (SLM)–an additive manufacturing processwherein metal powders are consolidated in a layer-by-layer manner, allowing the fabrication of complex components. SLMtypically involves complex physicochemical phenomena and results in laser-processing defects, which makes it difficult topredict the densification mechanisms of the melt pool. Therefore, a full-scale model was developed to investigate the thermalbehavior of the melt pool (e.g., temperature gradient distribution, melt pool dimensions, and cooling rate) and the resultantdensification activity under various laser energy density (η) values. In parallel, experimental investigations of the densificationbehavior and microstructural evolution were undertaken with the same SLM processing parameters. The challengesassociated with the SLM processability of Mg were comprehensively addressed. Both the peak temperature gradients withinthe molten pool and molten pool dimensions increased with increasing η, and an opposite trend was observed for the coolingrate. A low η (i.e., high scanning speed) results in a low operating temperature and short liquid lifetime, which in turn leadto poor wettability and many pore-chain and balling defects. However, high η values generated melt pool instability, whichresulted in extensive evaporation, cracks, and porosity. The SLM-processed samples had fine twin-like microstructures asa result of rapid solidification. The experimental and simulation results agreed well, validating the thermal behavior of themolten pool and underlying physical mechanism.
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