Research Article Open Access

Combined Thermal Radiation and Mixed Convection in an Inclined Circular Duct

W. Lakhal1, S. Trabelsi2, E. Sediki2 and M. Moussa1
  • 1 National Engineering School of Tunis, Tunisia
  • 2 Radiative Transfer Laboratory, Tunisia


Problem statement: Modeling thermal radiation with simultaneous buoyancy and forced convection for real gases flowing inside system with complex geometry is a difficult task encountered in engineering applications. Purpose of this study was to research numerically the interaction of mixed convection and thermal radiation in laminar air flow inside an inclined cylindrical duct with Uniform Wall Heat Flux (UWHF). This study highlighted the radiative double effects of water vapor in air flow on thermal and on dynamic fields. Approach: Flow equations and energy balance equation were solved simultaneously with temperature dependant thermophysical properties. An implicit finite difference technique was used to solve mass, momentum and energy equations. In order to take into account the non-gray radiative behavior of water vapor (H2O), a global absorption distribution function model was used to represent the infrared radiative properties. Results: Results were presented in term of temperature, velocity and radiative power fields and of evolution of bulk temperature and Nusselt numbers. Effects of thermal radiation on temperature and on velocity distributions were also examined. Conclusion/Recommendations: It was shown that inclination angle of duct had a significant effect on thermal and dynamic fields especially for thick medium. Radiation strongly affected the velocity profiles. Numerical results were discussed referring to available experimental data in order to improve estimations of engineering parameters.

American Journal of Engineering and Applied Sciences
Volume 2 No. 4, 2009, 590-602


Submitted On: 27 May 2009 Published On: 31 December 2009

How to Cite: Lakhal, W., Trabelsi, S., Sediki, E. & Moussa, M. (2009). Combined Thermal Radiation and Mixed Convection in an Inclined Circular Duct. American Journal of Engineering and Applied Sciences, 2(4), 590-602.

  • 15 Citations



  • Inclined duct
  • inclination angle
  • mixed convection
  • thermal radiation
  • cylindrical duct