Natural Convection In Cubical Enclosure Research Articles

내부 원형 실린더의 크기가 정육면체 밀폐계 내부의 3 차원 자연대류 현상에 미치는 영향

본 연구는 정육면체 밀폐계 내부에 존재하는 고온의 원형 실린더의 크기 변화에 따른 밀폐계 내부의 3 차원 자연대류 현상에 대한 수치해석을 수행하였다. 본 연구에서 고려한 Rayleigh 수는 103 부터 105 까지며 Prandtl 수는 0.7 이다. 내부 원형 실린더의 반경은 0.1L 부터 0.4L 범위에서 0.1L 간격으로 변경하였다. 본 연구에서 고려한 모든 Rayleigh 수와 실린더 반경의 범위에서 열유동장은 정상 상태의 특성을 보였다. 내부 원형 실린더의 크기가 증가하여 실린더 표면과 밀폐계 벽면이 가까워 질수록 실린더 표면과 밀폐계 벽면의 평균 Nusselt 수는 증가하였다. 내부 원형 실린더의 크기 변화에 따른 정육면체 밀폐계 내부의 자연대류 현상은 온도장, 유동장 및 표면 평균 Nusselt 수의 분포를 바탕으로 분석하였다.

Numerical Investigation of Natural Convection in Air Filled Cubical Enclosure with Hot Wavy Surface and Partial Partitions

Natural convection in cubical enclosure with hot surface geometry and partial partitions has been analysed. The geometry is a cube with wavy hot surface (three undulations) and three partitions. The investigation has been performed for different partitions lengths and Rayleigh number while the Prandtl number kept constant. This problem is solved by using the partial differential equations which are the equation of mass, momentum, and energy. The results obtained show that the hot wall geometry with partitions affects the flow and the heat transfer rate in the cavity. It has been found also that the mean Nusselt number decreases compared with the heat transfer in the undulated cubical cavity without partitions.

Investigation of natural convection in cubical enclosure using laser induced fluorescence

Temperature measurements are extremely important and they are used in many technical and engineering processes, including the analysis of natural convection. In contrast to the commonly used thermocouples and Pt100 temperature sensors, which allow point temperature measurements, laser induced fluorescence technique (LIF) allows the imaging of temperature fields throughout the area. An obvious disadvantage of thermocouples and Pt100 sensors is the possibility that the probes can affect the fluid flow, changing its structure. This problem does not appear in LIF measurements and better accuracy of temperature mapping is obtained. This work focuses on describing one-color LIF technique (using one fluorescent dye) in theoretical and practical terms. The experimental set-up is described, as well as a number of operations required to get the temperature field of the whole domain. The results of the natural convection process analysis in the configuration of one side wall heated and the opposite one cooled, with the use of laser induced fluorescence technique are presented.

Effect of Partial Partitions on Natural Convection in Air Filled Cubical Enclosure with Hot Wavy Surface

Natural convection in cubical enclosure with hot surface geometry and partial partitions has been analyzed. The geometry is a cube with wavy hot surface (three undulations) and three partitions. The investigation has been performed for different partitions lengths and Rayleigh number while the Prandtl number kept constant. This problem is solved by using the partial differential equations which are the equation of mass, momentum, and energy. The results obtained show that the hot wall geometry with partitions affects the flow and the heat transfer rate in the cavity. It has been found also that the mean Nusselt number decreases compared with the heat transfer in the undulated cubical cavity without partitions.

Influence of the uniform magnetic field on natural convection in cubic enclosure: experiment and numerical simulation

Thermomagnetic convection in cubic enclosure filled with magnetic fluid is studied by numerical simulation and physical experiment. Numerically it was discovered that a set of numerous convective structures exists in the cube and what structure is more stable depends on the comparison of magnetic and gravity forces. Experimentally a very essential dependence of heat flux on magnetic field was found both in vertical and horizontal magnetic field.

Petrov-Galerkin Finite Element Approach Using Exponential Test Functions for Three-Dimensional Natural Convection in Cubic Enclosure.

Recently, we presented a finite element scheme based on the Petrov-Galerkin weak formulation using exponential test functions, for solving the unsteady two-dimensional natural convection up to high Rayleigh numbers. The incompressible Navier-Stokes equations and energy equation are discretized by a semi-explicit scheme in which velocity and temperature are treated explicitly and pressure is treated implicitly with respect to the time variable. As the time-marching scheme, the fractional step method is also adopted in the work. The resulting numerical solutions demonstrate that the method is capable of solving the set of equations accurately and in a stable manner up to high Rayleigh numbers. The purpose of this paper is to extend the Petrov-Galerkin finite element method using exponential test functions, to three-dimensional natural convection problems. The validity of the present method is shown for unsteady flows in a cubic enclosure through comparison with other existing numerical solutions.