Control of exit flow and thermal conditions using two-layered thin films supported by flexible complex seals

This work considers flow and heat transfer inside an oscillatory disturbed two-layered thin film channel supported by flexible complex seals in the presence of suspended ultrafine particles. The governing continuity, momentum and energy equations for both layers are non-dimensionalized and categorized for small Reynolds numbers and negligible axial conduction. The deformation of the supporting seals is linearly related to both the pressure difference across the two layers and the upper plate's temperature based on the theory of the linear elasticity and the principle of the volumetric thermal expansion applied to the closed voids within the seals. It is found that the flow rate and heat transfer in the main thin film channel can be increased by an increase in the softness of the seals, the thermal squeezing parameter, the thermal dispersion effect and the total thickness of two-layered thin film. However, they decrease as the dimensionless thermal expansion coefficient of the seals and the squeezing number of the main layer increase. Both the increase in thermal dispersion and in the thermal squeezing parameter for the secondary layer are found to increase the stability of the intermediate plate. Furthermore, the two-layered thin film channel is found to be more stable when the secondary flow is free of pulsations or it has relatively a large pulsating frequency. Finally, the proposed two-layered thin film supported by flexible complex seals unlike other controlling systems does not require additional mechanical control or external cooling devices. (C) 2003 Elsevier Ltd. All rights reserved.