Microﬂuidics and Nanoﬂuidics (2018) 22:36
Eects of geometry factors on microvortices evolution in conned
· Min Xu
· Bin Zhou
· Zheng Wang
· Zhaomiao Liu
Received: 26 November 2017 / Accepted: 7 March 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Recently, microcavities have become a central feature of diverse microﬂuidic devices for many biological applications.
Thus, the ﬂow and transport phenomena in microcavities characterized by microvortices have received increasing research
attention. It is important to understand thoroughly the geometry factors on the ﬂow behaviors in microcavities. In an eﬀort
to provide a design guideline for optimizing the microcavity conﬁguration and better utilizing microvortices for diﬀerent
applications, we investigated quantitatively the liquid ﬂow characteristics in diﬀerent square microcavities located on one
side of a main straight microchannel by using both microparticle image velocimetry (micro-PIV) and numerical simulation.
The inﬂuences of the inlet Reynolds numbers (with relatively wider values Re = 1–400) and the hydraulic diameter of the
main microchannel (D
= 100, 133 μm) on the evolution of microvortices in diﬀerent square microcavities (100, 200, 400
and 800 μm) were studied. The evolution and characteristic of the microvortices were investigated in detail. Moreover, the
critical Reynolds numbers for the emergence of microvortices and the transformation of ﬂow patterns in diﬀerent microcavi-
ties were determined. The results will provide a useful guideline for the design of microcavity-featured microﬂuidic devices
and their applications.
Keywords Microﬂuidics · Microcavity · Microvortices · Flow pattern · Microparticle image velocimetry (micro-PIV)
Microﬂuidics of lab-on-a-chip systems have developed rap-
idly in last decade in multidisciplinary research ﬁelds (Utada
et al. 2005; Whitesides 2006; Sackmann et al. 2014), such
as physics, biology, chemistry, material science, and ﬂuid
mechanics (Lindström and Andersson-Svahn 2010; Mu
et al. 2013; Huang et al. 2017; Lin et al. 2017; Niu et al.
2011). Taking advantage of ﬂow characteristics in micro-
scale, microﬂuidics can be characterized as the science and
technology of manipulating and controlling ﬂuids in micro-
ﬂuidic devices (Stone et al. 2004; Baroud et al. 2010). The
ﬁne and precise control of ﬂuid ﬂows in microﬂuidic devices
is highly demanded in diﬀerent applications. To meet the
demand, diverse microﬂuidic devices with diﬀerent conﬁgu-
rations have been developed. It is signiﬁcantly important to
understand thoroughly the ﬂow behaviors in the microﬂuidic
devices (Bremond et al. 2008; Skelley et al. 2009; Anna
2016; Amini et al. 2014; Zhang et al. 2016).
Recently, microcavities have become an integral part of
diverse microﬂuidic devices in many microﬂuidic applica-
tions, for example controlling of the coalescence of micro-
droplets (Tan et al. 2004; Baroud et al. 2010; Shen et al.
2017a, b), trapping of microdroplets (Wang et al. 2009)
and cell culture (Yew et al. 2013; Luo et al. 2008; Liu et al.
2008; Vrhovec et al. 2011). Various microcavity geometric
conﬁgurations have been developed, for example microwells
(Cioﬃ et al. 2010; Hur et al. 2010; Jang et al. 2011) and
microgrooves (Khabiry et al. 2009; Park et al. 2010; Khabiry
et al. 2009) located on the bottom of the microchannel for
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s1040 4-018-2056-2) contains
supplementary material, which is available to authorized users.
* Feng Shen
College of Mechanical Engineering and Applied
Electronics Technology, Beijing University of Technology,
Beijing 100124, China
Beijing Key Laboratory of Advanced Manufacturing
Technology, Beijing University of Technology,
Beijing 100124, China
College of Civil Engineering and Architecture, Weifang
University, Weifang 261061, China