http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
반달 모양 돌출부의 위치에 따른 딤플 냉각 유로 열유동 특성
정명근(Myunggeun Jeong),박용갑(Yong Gap Park),하만영(Man Yeong Ha) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
This study carried out numerical analysis to study the flow and heat transfer characteristics in a dimpled cooling channel. A crescent-shaped protrusion was located on the upstream or downstream of the dimple. The main purpose of present study was to investigate the effect of the crescent-shaped protrusion location on the flow and heat transfer characteristics. A direct numerical simulation was conducted with a Reynolds number of 2800 and Prandtl number of 0.71 in the cooling channel. Three different shapes of channel geometry were considered including one general dimpled surface. The time averaged Nusselt number was calculated to evaluate the performance of the cooling channel in terms of heat transfer performance.
멀티스케일 하이브리드 기법을 이용한 나노 채널에서의 Poiseuille 유동에 대한 수치적 연구
정명근(Myunggeun Jeong),김영진(Youngjin Kim),하만영(Man Yeong Ha) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
This study shows the multi-scale hybrid method of the nano-channel flow system. In the nano-scale region, the continuum hypothesis breaks down and the conventional continuum models are no longer valid. To escape this phenomenon, we divided simulation procedures by two steps. For the first step, the fluid properties and fluid-solid combination effect are obtained by molecular dynamics. For the second step, the Finite Volume Method (FVM) used for a nano-channel flow using the fluid properties and the slip boundary condition at wall surface also simulates from the molecular dynamics results. This multi-scale hybrid method can be reduced a computational time compared to that of previous one.
딤플 뒤에 와류 발생기를 가지는 냉각 유로의 유동과 열전달 성능에 관한 수치적 연구
양재성(Jae Sung Yang),정명근(Myunggeun Jeong),박용갑(Yong Gap Park),하만영(Man Yeong Ha) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
In the present numerical study, the detailed flow structure and heat transfer characteristics with the newly designed dimple cooling channel were investigated. The surface geometry was proposed in the present study, it was a general dimple structure combining with a vortex generator behind the dimple, which is called dimple with vortex generator. The main purpose of surface geometry was to enhance the flow mixing and heat transfer in the flow-recirculating region that was generated by a dimple cooling channel. Direct numerical simulations (DNS) were carried out with a Reynolds number of 2800 and Prandtl number of 0.71 in the cooling channel. There were four different cases: a general dimple case, dimple with vortex generator cases with three different tip angles. The overall pressure drop and heat tranfer for dimple with vortex generator cases were higher than the general dimple case.
분자-연속체 하이브리드 기법을 이용한 구조물이 있는 나노 채널에서의 쿠에트 유동에 대한 수치적 연구
김영진(Youngjin Kim),정명근(Myunggeun Jeong),하만영(Man Yeong Ha) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.6
분자-연속체 하이브리드 기법은 연속체 유체역학으로 예측하기 어려운 마이크로/나노 스케일 유동에 대해 개발되고 발전해 왔다. 분자동역학은 고체표면 주변 영역에서 사용되고, 나머지 영역에서는 나비아스톡스 방정식이 사용된다. 본 연구에서는 나노채널에서 고체-액체 상호작용과 표면 거칠기의 영향을 연구하기 위해 분자-연속체 하이브리드 기법을 이용하여 쿠에트 유동을 해석하였다. 우리는 고체-액체 상호작용 힘인 표면 에너지와 표면 거칠기가 유동의 표면 경계조건에 영향을 주는 것을 발견하였다. 표면 에너지가 낮을 때에는 유동이 고체 표면에서 미끄러짐이 발생하였고, 표면 에너지가 증가함에 따라 미끄러짐의 크기가 감소하였다. 표면 에너지가 높을 때에는 로킹(locking) 경계조건이 형성되었다. 또한 표면 거칠기는 유동이 고체 표면에서 미끄러지는 것을 방해하여 로킹 경계조건이 잘 형성되도록 영향을 주었다. A molecular-continuum hybrid method was developed to simulate microscale and nanoscale fluids where continuum fluidics cannot be used to predict Couette flow. Molecular dynamics simulation is used near the solid surface where the flow cannot be predicted by continuum fluidics, and Navier-Stokes equations are used in the other regions. Numerical simulation of Couette flow was performed using the hybrid method to investigate the effect of solid-liquid interaction and surface roughness in a nanochannel. It was found that the solid-liquid interaction and surface roughness influence the boundary condition. When the surface energy is low, slippage occurs near the solid surface, and the magnitude of slippage decreases with increase in surface energy. When the surface energy is high, a locking boundary condition is formed. The roughness disturbs slippage near the solid surface and promotes the locking boundary condition.
분자-연속체 하이브리드 기법을 이용한 구조물이 있는 나노 채널에서의 Couette 유동에 대한 수치적 연구
김영진(Youngjin Kim),정명근(Myunggeun Jeong),하만영(Man Yeong Ha) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
Molecular-continuum hybrid method is developed for simulation micro-and nano-scale fluid where continuum fluidics cannot predict. Molecular dynamics simulation is used near the solid surface which connot be predicted by continuum fluidics and Navior-Stokes equation is used in other regions. We carried out molecular-continuum hybrid method to investigate effect of solid-liquid interaction and effect of roughness in a nano channel. We find that the surface energy such as solid-liquid interaction influence on boundary condition and the surface nanostructures have a effect on friction of the liquid nanoflow.
와류 발생기 크기 변화에 따른 딤플 냉각 유로 내부 유동 및 열전달 성능에 관한 수치적 연구
최유철(You Chul Choi),양재성(Jae Sung Yang),정명근(Myunggeun Jeong),박용갑(Yong Gap Park),하만영(Man Yeong Ha) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
A numerical investigation of the characteristics of flow structure and heat transfer in the cooling channel with the vortex generator combined dimple surface was conducted. The vortex generator was located in front of the dimple cavity. Different sizes of the vortex generator were considered in the present study. The main purpose of this study was to find the size effect of the vortex generator, and to enhance the flow mixing and heat transfer in the cooling channel. Direct numerical simulations (DNS) were carried out with a Reynolds number of 2800 and Prandtl number of 0.71 in the cooling channel.