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구강암 절제 및 재건 수술에 따른 기도 내 공기 유동 시뮬레이션
서희림(Heerim Seo),송재민(Jae Min Song),염은섭(Eunseop Yeom) 한국가시화정보학회 2020 한국가시화정보학회지 Vol.18 No.3
Oral cancer surgery changes the morphologic characteristics of the human upper airway. These changes can affect the flow patterns. In this study, computational fluid dynamics (CFD) simulations with transient solver were performed to numerically investigate the air flows in the human upper airways depending oral cancer surgery. 3D reconstructed models were obtained from 2D CT images of one patient. For the boundary condition, the realistic breathing cycle of human was applied. The hydraulic diameters of cross-sections for post-surgical model are changed greatly along streamwise direction, so these variations can cause higher wall shear stress and flow disturbance compared to pre-surgical model. The recirculation flows observed in the protruding region result in the relatively large pressure drop. These results can be helpful to understand the flow variations after resection surgery of oral cancer.
오목한 반구면의 Jet Impingement/Effusion Hole 주변 유동 특성에 대한 실험과 시뮬레이션의 비교
윤성지,서희림,염은섭 한국가시화정보학회 2022 한국가시화정보학회지 Vol.20 No.2
Flow characteristics of jet impingement over concave hemispherical surface with effusion cooling holes is relatively more complex than that of a flat surface, so the experimental validation for computational fluid dynamics (CFD) results is important. In this study, experimental results were compared with simulation results obtained by assuming different turbulence models. The vortex was observed in the region between the central jets where the recirculation structure appeared. The different patterns of vorticity distributions were observed for each turbulence models due to different interaction of the injected jet flow. Among them, the transition k-kl-ω model predicted similarly not only the jet potential core region with higher velocity, but also the recirculation region between the central jets. From the validation, it may be helpful to accurately predict heat and mass transfer in jet impingement/effusion hole system.
판진싱,이수환,서희림,김동우,염은섭 한국가시화정보학회 2022 한국가시화정보학회지 Vol.20 No.3
In the fan module of the intercooling refrigerator, a drain hole structure was designed for stable drainage of defrost water. However, the airflow passing through the drain hole can disturb flow features around the evaporator. Since this backflow leads to an increase in flow loss, the accurate experimental and numerical analyses are important to understand the flow characteristics around the fan module. Considering the complex geometry around the fan module, three different turbulence models (Standard k-ε model, SST k-ω model, Reynolds stress model) were used in computational fluid dynamics (CFD) analysis. According to the quantitative and qualitative comparison results, the Standard k-ε model was most suitable for the research object. High-accuracy results well match with the experiment result and overcome the limitation of the experiment setup. The method used in this study can be applied to a similar research object with an orifice outflow driven by a rotating blade.
PIV 측정 및 수치해석을 이용한 구강암 수술에 따른 기도 형상 내 유동 특성
홍현지(Hyeonji Hong),안세현(Se Hyeon An),서희림(Heerim Seo),송재민(Jae Min Song),염은섭(Eunseop Yeom) 한국가시화정보학회 2021 한국가시화정보학회지 Vol.19 No.3
Oral cancer surgery typically consists of resection of lesion, neck dissection and reconstruction, and it has an impact on the position of hyoid bone. Therefore, morphological change of airway can occur since the geometric parameter of airway is correlated with the hyoid bone. Airflow is affected by geometry of the airway. In this study, flow characteristics were compared between pre- and post-surgery models by both particle image velocimetry (PIV) and numerical simulation. 3D model of upper airway was reconstructed based on CT data. Velocity is accelerated by the reduced channel area, and vortex and recirculation region are observed in pre- and post-surgery models. For the post-surgery model, high pressure distribution is developed by significantly decreased hydraulic diameter, and the longitudinal flow stream is also interrupted.