The effects of variable physical properties on the flow and heat transfer characteristics of simultaneously developing slip-flow in rectangular microchannels with constant wall heat flux are numerically investigated. A co-located finite-volume method is used in order to solve the mass, momentum and energy equations in their most general form. Thermophysical properties of the flowing gas are functions of temperature, while density and Knudsen number are allowed to change with both pressure and temperature. Different Knudsen numbers are considered in order to study the effects of slip-flow. Simulations indicate that the constant physical property assumption can result in under/over-prediction of the local friction and heat transfer coefficients depending on the problem configuration. Density and thermophysical property variations have significant effects on predicting flow and heat transfer characteristics since the gas temperature constantly changes as a result of the applied wall heat flux. Heat transfer coefficient is affected both due to the change in the velocity field and change in thermophysical properties. Also temperature dependence of the local Knudsen number can significantly alter the friction coefficients due to its strong dependence on slip conditions. The degree of discrepancy varies for different cases depending on the Knudsen number, and the applied heat flux strength and direction (cooling versus heating).

This content is only available via PDF.
You do not currently have access to this content.