Options
Physics of fluid flow in an hourglass (converging-diverging) microchannel
Journal
Physics of Fluids
ISSN
10706631
Date Issued
2022-05-01
Author(s)
Goli, Sandeep
Saha, Sandip K.
Agrawal, Amit
Abstract
This work presents the numerical and experimental study of flow physics and characterization in hourglass microchannels at different geometric and flow parameters such as convergence-divergence angle, width ratio, length, aspect ratio, and Reynolds number. The first part of the study discusses the importance of finding a unique length scale to represent an hourglass microchannel. This representative dimension is proposed at a distance of L/2.9 (L is the total length of the microchannel) from the inlet of the microchannel by using a frictional equivalence concept between uniform and hourglass microchannels. The proposed length scale is unique as it remains independent of geometric and flow variables. The study of local flow physics shows that this length scale identifies the region that governs the overall flow behavior of the microchannel. The results also show that the pressure drop is an inverse function of convergence-divergence angle and aspect ratio, whereas the width ratio and length are direct functions. In addition, the pressure drop shows linear behavior with the volume flow rate (Reynolds number) similar to that of a uniform microchannel except at a higher volume flow rate for convergence-divergence angle or higher width ratio. This non-linear behavior is explained with the help of hydrodynamic resistance and velocity streamlines in the last part of this study. Furthermore, the convergence-divergence angle and the width ratio are identified as critical parameters to characterize the flow. Overall, the present study gives insights into the influence of the convergence-divergence effect due to critical parameters on the flow characteristics, which could help design hourglass microchannels for many engineering applications.