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송정철(Jeong Chul Song),안준(Joon Ahn),이준식(Joon Sik Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
An immersed boundary method is proposed to numerically analyze the conjugate heat transfer problem. Momentum forcing is applied to set the velocity inside the solid to be zero so that the energy equation is reduced to the heat diffusion equation. An effective conductivity is introduced to satisfy the continuity of the heat flux at the interface, which is obtained by considering the heat balance at the interface or using a harmonic mean formulation. The method is validated against an analytic solution of laminar channel flow with conducting solid wall. The method is applied to two dimensional ribbed channel flow in the laminar regime.
이준식(Joon-Sic Lee),정인호(In-Ho Jung),유경선(Kyung-Sun Yoo),정병조(Byung-Jo Jung),서정철(Jung-Chul Seo),현동훈(Dong-Hoon Hyun) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-
This study is aimed to develop low energy consuming heater. For healthy life, abdomen for men, lower body for women should be warmed up. A heater using nano surface heat with character with is Hello Kitty for now wil be in great demands. With this study, I wish all humankind can be healty and happy.
송정철(Jeong Chul Song),안준(Joon Ahn),이준식(Joon Sik Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Numerical Simulations are performed to analyze the conjugate heat transfer of turbulent flow in a ribbed channel with conducting solid wall. An immersed boundary method is used to figure out the heat transfer effect in the solid region on that in the fluid region in an unitary computational domain. In order to satisfy the continuity of the heat flux at the solid-fluid interface, an effective conductivity is introduced. A large eddy simulation technique is used to predict turbulent flow. Results show that heat flux is concentrated to the rib below the channel wall and flows outward mainly around the edge of the rib. However, the local Nusselt number shows no significant difference with the pure convection case.
요철이 설치된 채널 내에서 레이놀즈수와 열용량비에 따른 복합열전달 특성
송정철(Jeong Chul Song),안준(Joon Ahn),이준식(Joon Sik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Numerical simulations are conducted to analyze conjugate heat transfer characteristics in a ribbed channel. In this simulation, the effects of Reynolds number and heat capacity of the solid channel wall on convective heat transfer are observed in the turbulent flow regime. In the case of the conducting wall against isothermal wall, the relative ratio of the thermal resistance between the solid wall and the flow field varies with Reynolds number. Thus the characteristics of the conjugate heat transfer are changed with the Reynolds number. Heat capacity ratio affects the temperature fluctuation inside solid wall. The temperature fluctuation inside the solid wall decreases with increasing the heat capacity of the solid wall so that the convective heat transfer increases. When the thermal conductivity ratio is smaller than 10, the effects of flow characteristics on heat transfer are changed.
An Immersed Boundary Method for Conjugate Heat Transfer Analysis
Jeong Chul Song(송정철),Joon Ahn(안준),Joon Sik Lee(이준식) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.11
An immersed boundary method is proposed for the analysis of conjugate problems of convective heat transfer with conducting solids. Inside the solid body, a momentum forcing is applied to set the velocity to be zero. The thermal conductivity ratio and heat capacity ratio between the solid body fluid are introduced so that the energy eqyatuib us reduced to the heat diffusion equation. At the solid-fluid interface, an effective conductivity is introduced to satisfy the heat flux continuity. The effective thermal conductivity is obtained by considering the heat balance at the interface or by using a harmonic mean formulation. The method is first validated against the analytic solution to the heat transfer problem in a fully develooped laminar channel flow with conducting solid walls. Then it has been applied to a laminar channel flow with a squared shaped obstacle to show its validity for the geometry with sharp edge. Finally the validation for a curvilinear solid body is accomplished for a laminar flow through arrayed cylinders.
Bioreactor 의 작동 조건에 따른 혼합 시간 변화에 대한 연구
이현우(Hyunwoo Lee),이준철(Joon-Chul Lee),서영진(Youngjin Seo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Bioreactor 는 세포를 이용하여 합성, 분해, 화학적 반응을 인공적으로 발생시켜 세포를 증식시키기 위한 장치이다. Bioreactor 를 이용하여 세포를 배양하는 방법은 다양한 산업에서 사용되고 있으며 연구가 계속 진행되고 있다. 본 연구에서는 실험과 수치해석을 진행하여 수치해석의 신뢰성을 확보하였으며 검증된 수치해석 모델을 사용하여 다양한 작동 조건에서의 bioreactor 의 mixing time 을 예측하였다. Bioreactor is a device for proliferating cells by artificially generating synthesis, decomposition, and chemical reactions using cells. The method of culturing cells using a bioreactor is being used in various industries and research is ongoing. In this study, the reliability of the numerical analysis was secured by conducting experiment and numerical analysis, and the mixing time of the bioreactor under various operating conditions was predicted using the verified numerical analysis model.
딤플이 있는 채널 내부의 난류 열전달에 대한 큰에디모사
이영옥(Young Ok Lee),안준(Joon Ahn),송정철(Jeong Chul Song),이준식(Joon Sik Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Large eddy simulation (LES) data are presented which describe flow and heat transfer characteristics in a dimpled channel. The ratios of dimple depth and channel height to the dimple print diameter are 0.2 and 0.5, respectively. The bulk Reynolds number is 20,000. Dimples are arranged on a side of the channel in a staggered array. LES predicts quantitatively well the local Nusselt number distribution, which has not been reproduced by RANS or other turbulence models. Heat transfer rate is enhanced because all three components of velocity fluctuations are intensified along the shear layer above the recirculation bubble in the dimple. The urms is locally maximized on the wall around the downstream rim of the dimple while the wrms does around the reattachment point. The instantaneous flow and thermal fields show that the heat transfer in the dimpled channel is enhanced by the vortices generated at the shear layer.