Simultaneously developing laminar flow and heat transfer in the entrance region of flat and circular conduits
A new integral method of solution for the combined hydrodynamic and thermal-entrance-region problem for laminar flow through parallel-plate channels and circular tubes was developed. The new analysis adapts the hydrodynamic inlet-filled region concept of Ishizawa (1966) to the thermal entry length problem. A new thermal-transition region, called the thermally-filled region, was introduced between the thermal inlet boundary-layer region and the fully developed region. A thermal shape factor for the thermally-filled region was properly defined. This factor guaranteed smooth transition of all pertinent thermal quantities from the inlet boundary-layer region to the fully developed region. With the new model, the velocity and temperature profiles, the skin friction factors, and the local Nusselt numbers approached their corresponding fully developed conditions asymptotically. Solutions were obtained for the combined entry length problem for laminar flow through circular tubes and parallel-plate channels for the constant wall temperature and constant wall heat flux boundary conditions. Results for variation of the local Nusselt number with axial distance agreed well with numerical solutions available in the literature.
- Research Organization:
- Colorado School of Mines, Golden, CO (USA)
- OSTI ID:
- 5293177
- Country of Publication:
- United States
- Language:
- English
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