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Parameter Study of Boiling Model for CFD Simulation of Multiphase-Thermal Flow in a Pipe
Soh-Myung Chung,Yong-Seok Seo,Gyu-Mok Jeon,Jae-Won Kim,Jong-Chun Park 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.1
The demand for eco-friendly energy is expected to increase due to the recently strengthened environmental regulations. In particular, the flow inside the pipe used in a cargo handling system (CHS) or fuel gas supply system (FGSS) of hydrogen transport ships and hydrogen-powered ships exhibits a very complex pattern of multiphase-thermal flow, including the boiling phenomenon and high accuracy analysis is required concerning safety. In this study, a feasibility study applying the boiling model was conducted to analyze the multiphase-thermal flow in the pipe considering the phase change. Two types of boiling models were employed and compared to implement the subcooled boiling phenomenon in nucleate boiling numerically. One was the Rohsenow boiling model, which is the most commonly used one among the VOF (Volume-of-Fluid) boiling models under the Eulerian-Eulerian framework. The other was the wall boiling model, which is suitable for nucleate boiling among the Eulerian multiphase models. Moreover, a comparative study was conducted by combining the nucleate site density and bubble departure diameter model that could influence the accuracy of the wall boiling model. A comparison of the Rohsenow boiling and the wall boiling models showed that the wall boiling model relatively well represented the process of bubble formation and development, even though more computation time was consumed. Among the combination of models used in the wall boiling model, the simulation results were affected significantly by the bubble departure diameter model, which had a very close relationship with the grid size. The present results are expected to provide useful information for identifying the characteristics of various parameters of the boiling model used in CFD simulations of multiphase-thermalflow, including phase change and selecting the appropriate parameters.
동시 병발한 그레이브스병과 중증근무력증의 수술적 치험 1예
정윤석,진윤미,소의영,김명욱,류기선,류한영,주인수 대한내분비학회 1997 Endocrinology and metabolism Vol.12 No.3
Graves disease occur in association with myasthenia gravis is rare. We report a case of Graves disease and myasthenia gravis treated by bilateral subtotal thyroidectomy and total thymectomy simultaneously. A 37 year old woman was admitted with anterior neck mass and ptosis. Various examinations were compatible with combined Graves disease and myasthenia gravis. The bilateral subtotal thyroidectomy and total thymectomy were done simultaneously. The pathologic diagnosis was Graves disease and thymic hyperplasia. The patients postoperative course was uneventful. The thyroid function of patient became euthyroid and the clinical symptoms related with myastenia gravis resolved during follow up period. (J Kor Soc Endocrinol 12:473-477, 1997)
Experimental study on sloshing reduction effects of baffles linked to a spring system
Kim, Sung-Pill,Chung, Soh-Myung,Shin, Woo-Jin,Cho, Dae-Seung,Park, Jong-Chun Elsevier 2018 Ocean engineering Vol.170 No.-
<P><B>Abstract</B></P> <P>The liquid sloshing phenomenon which damages the structures of various systems and affects their global motion of the system is one of the most important problems in naval architecture and ocean engineering. Thus far, several efforts have been attempted to reduce the fluid impact load induced by sloshing, such as the installation of additional equipment like baffles to avoid the resonance period with the tank or to restrain violent sloshing flow. In this paper, a concept of “moving baffles” is introduced, which is containing a spring system as one of the attempts for reducing sloshing impact. To observe the sloshing reduction effect of the moving baffles, a series of sloshing experiments considering the sway motion of a rectangular tank was conducted, and the experimental results for the case without any additional equipment were compared to those for the case with the baffles linked to two types of spring systems with different stiffness. The image, pressure, and force data were obtained through the sloshing experiments, and the effectiveness of the spring baffles was examined by comparing the statistical analysis results of the extremal probability and exceedance probability distribution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A concept of “moving baffles” is introduced, which is containing a spring system as attempts for reducing sloshing impact. </LI> </UL> </P>