Dissertation > Excellent graduate degree dissertation topics show

Direct Numerical Simulation of Natural Convection in a Square Cavity Filled with Fixed Particles

Author: ChenKai
Tutor: ShaoXueMing；YuZuoSheng
School: Zhejiang University
Course: Fluid Mechanics
Keywords: directing-forcing fictitious domain method square cavity natural convection porous medium flow reversals
CLC: TK124
Type: Master's thesis
Year: 2011
Downloads: 34
Quote: 0
Read: Download Dissertation

Abstract


The phenomenon of particle flow with heat transfer is common in nature and various industry fields. However, studies on this complex internal flow and its heat transfer characteristics are still insufficient. In this paper, the problem of natural convection in square cavity with fixed particles was direct simulated based on the fictitious domain method and two cases with different boundary conditions were investigated.For the problem of natural convection in porous medium, the structure of porous media was approximated by distributing solid particles in the cavity. The influences of the particles’ number, distributing pattern and particle shape on the heat transfer of the internal flow were analyzed. The results reveal that, with a high Rayleigh number, the heat of natural convection is mainly transferred by the circumfluence which is induced by the heat convection around the boundary. There is a high-speed flow area near the vertical walls. Its velocity increases with the Ra number, while the width of this area decreases with the Ra number. When the Ra number and the solid volume fraction are kept constant, the mean Nusselt number of the boundary decreases with the increase of the particles number in the particle regular distributing cases, which indicates the decrease of the heat transfer efficiency. Further analysis on the flow fields shows that the effects of the distance between the outermost row of particles and the vertical boundary on the heat transfer efficiency are significant. For the random particle distributing cases, the heat transfer efficiency is higher than that of the regular particle distributing cases at a high Ra number. In addition, the influence of the particle shape on heat transfer is weak.The spontaneous flow reversals were studied for the Rayleigh-Benard convection. The periods of reversals are exponential growth as the Ra number increase when there is no particle, and the reversals occur only in a certain range of Ra number and Pr number. The reversal periods are shortened if a particle is fixed in the cavity center. It increases linearly as the increase of the Ra number, and decrease when the particle radius increases. Changing the particle position along the X=0.5, the reversal periods is largest when the particle is fixed in the cavity center. The periods decrease no matter increasing or decreasing the particle’s vertical position, and its trend is symmetrical with the distance from the center. Diagonal arrangement of two particles which located at the two vertices of the diagonal corner eddies in the cavity can prevent the occurrence of the flow reversals.

Related Dissertations

  1. Porous Medium Burner Operation Parameter Study and Numerical Simulation,TK16
  2. Research and Numerical Simulation of Highly Effective Heat Transfer Type Cyclone Separator,TQ051.8
  3. Study on Guide Wave Propagation in Saturated Porous Media,P631.4
  4. Parallel Two-Phase Flow Simulations and Its Implications Using the Lattice Boltzmann Method,O359
  5. The Residua of Oil Pollutants and Its Hydrodynamic Effects on Porous Medium,X523
  6. Experimental Study on Combustion and Heat Transfer Characteristics of Porous Midea Gas Water Heater and Prototype Design,TS914.252
  7. Thermoelectric material heat transfer process numerical simulation of porous media,TB34
  8. The Effect of Concentration Diffusion on Thermal Convection in a Flow of the Rivlin-Ericksen Fluid in Porous Medium,O357.3
  9. Darcy Scale Modeling for Two-phase Flow in Porous Media from a Dynamic Pore-scale Network,O359
  10. Blow-up Property of a Porous Medium System with Nonlocal Boundary Conditions,O382
  11. Stress Wave Propagation in Fluid-Saturated Porous Media under Impact Loading,O347.4
  12. Study on Premixed Combustion Mechanism of Fuel Gas in Gradually-varied Porous Media,TK16
  13. Fundamentally Studies about Applying Porous Medium to a New Cooling Technique,TK124
  14. Material Instability Research and Coupled Chemo-Hydro-Mechanical Manifold Element Analysis for Porous Media,O357.5
  15. Borehole Stablity Analysis of Horizontal Well with Elasto-Plastic Seepage,TE21
  16. Research on the Gas-liquid Two-phase Fluid Flow in Porous Channel,TL334
  17. Hydrodynamic Behaviors of Waves Interaction with Porous Medium,TV139.2
  18. Theoretical and Numerical Study of Modified Biot’s Models, Acoustoelectric Well Logging and Acoustic Logging While Drilling Excited by Multipole Acoustic Sources,P631.8
  19. Study on the Sand Liquefaction in the Process of Vibrating Grouting,TU41.4
  20. Elemental Study on Superadiabatic Engine Based on the Porous-Medium Combustion Technique,TK401
  21. Investigation on Dynamic Response of Unsaturated Soils and Foundation,TU435

CLC: > Industrial Technology > Energy and Power Engineering > Thermal engineering, heat > Thermal Engineering Theory > Heat Transfer
© 2012 www.DissertationTopic.Net  Mobile