Session: 11-45-01: Applications of Computational Heat Transfer

Paper Number: 99037

99037 - Pressure and Shear Driven Flow in Micro- and Minichannels 

The flow and the associated transport processes in microchannels and minichannels are generally driven by an imposed pressure difference. Examples of such flows include heat sinks for thermal management of electronic systems and flow in dies in polymer extrusion. The fluid may be Newtonian or non-Newtonian, depending on the application under consideration, being the latter for polymer processing. Also, in several practical circumstances, the shear imparted by a moving surface may also act in addition to the pressure, aiding the pressure-driven flow in some cases and opposing it in others. Such flows arise, for example, in processes like coating, cooling and thermal treatment of moving wires, rods, and fibers. In the optical fiber or wire coating process, both the entrance of the moving surface into a reservoir of the coating fluid as well as the exit involve flow driven by shear and pressure. The flow and thermal transport in the channel strongly influence the resulting coating and the thermal processing of the material. Cooling of optical fibers after the drawing process is another important step in the overall fiber fabrication process. The shear is imparted by the moving fiber and inert gases are driven under pressure into the cooling channel. This paper considers such processes, where the channel flow and heat transfer are driven by both shear and pressure. The transport processes at both the inlet and outlet regions of the channels are of intertest and are discussed in detail. Experimental and analytical/numerical results are presented to characterize the flow in the channel and at the entrance and exit. The increase in pressure in channels with narrowing flow domains, as is commonly employed in dies, is determined and compared with the imposed pressures. It is seen that, in many practical problems, the shear could generate much higher pressures than the typical imposed pressures. The flow is thus dominated by the shear effects due to the moving surface. The flow is found to develop very rapidly, resulting in transport in a largely developed flow region. Thus, the transport rates are small over much of the flow region. Methods to enhance the heat transfer under these circumstances are outlined. Comparisons between experimental and numerical results show fairly good agreement. Therefore, the validity of the analytical and numerical models developed for these processes is established. The results obtained can also be used for the design of the relevant systems, particularly in materials processing and manufacturing.

Presenting Author: Yogesh Jaluria Rutgers University

Presenting Author Biography: Dr. Yogesh Jaluria is Board of Governors Professor and Distinguished Professor at Rutgers, the State University of New Jersey. His research work is in the field of thermal science and engineering, covering areas like convection, fires, materials processing, thermal management of electronics, energy, and environment. He is the author/co-author of 10 books, including 4 extensively expanded revised versions, and editor/coeditor of 15 conference proceedings, 13 books, and 13 special issues of archival journals. He has contributed over 600 technical articles, including over 228 in archival journals and 22 book chapters. He has 3 patents and 7 copyrighted software. He has received several awards and honors for his work, such as the prestigious 2020 Holley Medal from ASME for his work on optical fiber drawing, the 2007 Kern Award from AIChE, the 2003 Robert Henry Thurston Lecture Award from ASME, and the 2002 Max Jakob Memorial Award, the highest international recognition in heat transfer, from ASME and the AIChE. He has served as Department Chairman and as Interim Dean of Engineering. He served as Editor-in-Chief of the Journal of Heat Transfer (2005-2010) and as Editor of Computational Mechanics. He is an Honorary Member of ASME, a Fellow of AAAS, ASTFE and APS, and an Associate Fellow of AIAA. He served as the founding President of the American Society of Thermal and Fluids Engineers (ASTFE) from 2014 to 2019.

Authors:

Yogesh Jaluria Rutgers University