탄성혈관내 맥동유동에서 속도 및 벽면전단응력에 대한 수치해석

김창녕,김정호 경희대학교 자연과학종합연구원 1999 자연과학논문집 Vol.5 No.-

Numerical analysis are focused on the flow patterns and wall shear stress under unsteady pusaltile flow condition with wall motion. Flow is considered as a non-Newtonian fluid and the constitute equation of blood is used for numerical analysis. Distributions of velocity and wall shear stress in the parallel channel model are calculated to investigated the differences of flow characteristics of unsteady pulsatile flow and to compare flow characteristics of a Newtonian fluid with that of a non-Newtonian fluid.

두 전극이 있는 장방형관에서의 자기유체유동

김창녕 한국항공우주학회 1991 한국항공우주학회 학술발표회 논문집 Vol.- No.-

Numerical examination of liquid metal magnetohydrodynamic flow in multiple channels in the plane perpendicular to the magnetic field

김창녕 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

In the current study, investigated are steady-state, three-dimensional liquid metal (LM) magnetohydrodynamic (MHD) flows in a conduitsystem including three sub-channels with co-current flows under a uniform magnetic field. Though there have been numerous analytic,experimental and numerical studies on MHD duct flow, detailed flow characteristics of a LMMHD flow in a conduit system withmultiple channels have not been reported much. The current study predicts detailed behaviors of the flow velocity, pressure, current andelectric potential of LMMHD flows in multiple channels in the plane perpendicular to the magnetic field. Here, the characteristics of theMHD flow in a conduit system with multiple channels are elucidated. The mass flow rate in each of outer channel turns out to be higherthan that in the central channel. The mechanism governing the imbalance of mass flow rate in the sub-channels is discussed in detailbased on the interdependency of flow variables in LMMHD flow.

Inertial migration and multiple equilibrium positions of a neutrally buoyant spherical particle in Poiseuille flow

김창녕,최청렬 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4

The radial migration of a single neutrally buoyant particle in Poiseuille flow is numerically investigated by direct numerical simulations. The simulation results show that the Segré and Silberberg equilibrium position moves towards the wall as the Reynolds number increases and as the particle size decreases. At high Reynolds numbers, inner equilibrium positions are found at positions closer to the centerline and move towards the centerline as the Reynolds number increases. At higher Reynolds numbers, the Segré and Silberberg equilibrium position disappears and only the inner equilibrium position exists. We prove that the inner annuluses in the measurements of Matas, Morris & Guazzelli (J. Fluid Mech. 515, 171-195, 2004) are not transient radial positions, but are real equilibrium positions. The results on the inner equilibrium positions and unstable equilibrium positions are new and convince us of the existence of multiple equilibrium radial positions for neutrally buoyant particles.

자장이 걸린 Czochralski 유동장에 대한 수치 해석 ( A Numerical Simulation of Magnetic Czochralski Flow Field )

김창녕 대한기계학회 1994 대한기계학회 춘추학술대회 Vol.- No.-

A NUMERICAL SIMULATION FOR THE PERFORMANCE CHARACTERIZATION OF HEAT SINKS : Heat Sink 의 특성확인을 위한 수치적 Simulation

김창녕,문성일 한국산업정보응용수학회 1999 한국산업정보응용수학회 Vol.3 No.2

A numerical simulation has been carried out for the performance characterization of heat sinks in electronic equipment. Heat transfer characteristics have been analyzed for various design parameters including the shape of heat sink, thickness of fin base and fin pitches. A commercial program called Flotherm has been employed for the numerical calculation. Optimal design of the heat sink has been persued which is closely related with the reduction of heat resistance involved in conduction and convection of heat.

실리콘 단결정 성장에서 용융물질의 회전효과

김창녕,이제희 慶熙大學校 材料科學技術硏究所 1996 材料科學技術硏究論集 Vol.9 No.-

For various angular velocities of crucible and crystal, the characteristics of melt flows, temperatures and concentrations of oxygen are numerically studied in the Czochralski furnace with a uniform axial magnetic field. With an assumption that two velocity components in the meridional plane and circumferential velocity, temperature, electric current intensity have reached the steady state, unsteady concentration field of oxygen has been analyzed with an initially uniform oxygen concentration. when the angular velocities of crucible and crystal are remarkable, oxygen cannot be easily transported to the area close to the bottom of crystal due to the noticeable centrifugal force. Therefore absorption rate of oxygen to the surface of crystal growth is small and is nearly uniform in the radial direction. On the contrary, when the angular velocities are small, the absorption rate of oxygen shows large gradient in the radial direction.

경사진 자장의 영향을 받는 관안에서의 자기유체유동

김창녕 金烏工科大學校 1990 論文集 Vol.11 No.-

A numerical procedure ws devised to predict the characteristics of the flow field in a liquid metal magnetohydrodynamic(MHD) flow. By the use of the procedure, a steady-state, incompressible, viscous, three-dimensional MHD flow under the influence of a magnetic field applied obliquely at an angle of 45˚ to each side wall of a rectangular duct has been studied at an extremly low magnetix Reynolds number by means of a finite volume method. The use of the control volume approach enables the implementation of the corrective step based on the fluid flux across the face of the volume, which contributes to convergence and physical accuracy. Numerical results shows that the axial velocities are large on the diagonal region of the cross-section lying parallel to the magnetic field with the peak velocities located at the corners.

자기장이 인가된 초크랄스키 실리콘 단결정 성장에서 산소의 거동특성

김창녕 慶熙大學校 1998 論文集 Vol.27 No.-

The characteristics of concentration of oxygen are numerically investigated for various magnetic fields in the Czochralski single crystal growth. Flow fields with uniform axial and cusp magnetic fields are studied for concentration of oxygen. The distributions of temperature and concentration of oxygen are strongly dependent on flow field. Uniform axial magnetic field suppresses the inward flow at the free surface so that the gradient of oxygen concentration is much large at the free surface and is very small at the growing surface of crystal. While in cusp magnetic field, the gradient of oxygen concentration on the growing surface decreases as the magnetic field increases.

A numerical study on unsteady natural convection of air with variable viscosity over an isothermal vertical cylinder

김창녕,Hari Ponnamma Rani 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.3

The present study deals with the boundary layer flow and heat transfer of unsteady laminar free convection flow past a semi-infinite isothermal vertical cylinder immersed in air. The fluid viscosity is assumed to vary with the temperature. An implicit finite-difference method has been employed to solve the governing non-dimensional boundary layer equations. A parametric study is performed to illustrate the influence of variable viscosity on the velocity and temperature profiles. The numerical results reveal that the viscosity has significant influences on the transient velocity and temperature profiles, average skin-friction coefficient and the average heat transfer rate. The results indicate that as the viscosity parameter increases, the temperature and the skin-friction coefficient increase, while the velocity near the wall and the Nusselt number decrease.