Numerical Simulation of Turbulent Flow Heat Transfer in the Entrance Region of Microchannels

Sadeghi, Arman | 2009

651 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39038 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nouri Borujerdi, Ali
  7. Abstract:
  8. In this thesis the steady state convective heat transfer for turbulent, two-dimensional, incompressible gas flow in a circular microchannel under slip flow and temperature jump conditions is numerically investigated by means of finite volume scheme. The low Reynolds number k-ε turbulence model is employed using a new boundary condition for turbulent kinetic energy at solid surface. To calculate variables at control volume surfaces in the axial direction upwind differencing scheme and in the radial direction central differencing scheme are used. Rhie-Chow interpolation technique is used to prevent pressure field oscillations. The set of discrete equations are solved using SIMPLE Algorithm. In the solutions of the coupled algebraic equations, Tri-Diagonal Matrix Algorithm (TDMA) is applied. The effect of Knudsen number on Nusselt number and friction factor are presented in graphical form in the entrance region and under fully developed conditions. The results show that the local Nusselt number and the friction factor for the microchannels are lower than those predicted by the correlations for the conventional tubes. The decrement of the Nusselt number at Re=4000 and Kn=0.1 for a fluid with Prandtl number close to unity is over 60% which is notably larger than that for laminar flow. Also results show that as Knudsen number increases the entry length increases. The increase is about 60% for Re=4000 and Kn=0.1
  9. Keywords:
  10. Microchannel ; Turbulent Flow ; Numerical Solution ; Knudsen Number ; Slip Flow

 Digital Object List