An Experimental Study of Momentum and Thermal Transport in Flow Through Smooth- and Rough-Wall Microchannels
Natrajan, Vinay Kumar
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https://hdl.handle.net/2142/87759
Description
Title
An Experimental Study of Momentum and Thermal Transport in Flow Through Smooth- and Rough-Wall Microchannels
Author(s)
Natrajan, Vinay Kumar
Issue Date
2009
Doctoral Committee Chair(s)
Christensen, Kenneth T.
Department of Study
Theoretical and Applied Mechanics
Discipline
Theoretical and Applied Mechanics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Language
eng
Abstract
Local Nusselt number (Nu) for smooth-wall laminar flow in the range 200 ≤ Re ≤ Recr agree well with macroscale predictions in both the thermally-developing and -developed regimes With increasing roughness, while an enhancement in local Nu is noted in the thermally-developing regime, no measurable influence is observed upon attainment of a thermally-developed state. These observations are supported by temperature profiles which suggest that the thermal boundary layer may be regenerated locally by roughness in the thermal entrance region of the flow. In the transitional regime, mean temperature profiles for the smooth- and rough-wall cases show deviation from fully-developed laminar behavior for Re > Recr. Finally, estimates of bulk Nu indicate enhancement in convective heat transfer over the smooth-wall case with increasing surface roughness in the laminar, transitional and turbulent regimes, though the smooth-wall data are in excellent agreement with macroscale predictions for laminar and turbulent flow. While a shift in the transitional pathway of the thermal transport behavior toward lower Re appears partially attributable for this enhancement with increasing roughness, it appears that turbulent convection also contributes significantly once transition is initiated.
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