TY - JOUR
T1 - Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid
AU - Yue, Pengtao
AU - Feng, James J.
AU - Liu, Chun
AU - Shen, Jie
N1 - Funding Information:
Acknowledgment is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research. J.J.F. was also supported by the NSF (CTS-0229298, CTS-9984402), the NSERC's Canada Research Chair and Discovery programs, and the NNSF of China (Nos. 20174024 and 20490220). J.S. was supported by the NSF (DMS-0074283, DMS-0311915). C.L. was supported by the NSF (DMS-0405850).
PY - 2005/10/1
Y1 - 2005/10/1
N2 - Nematic-isotropic interfaces exhibit novel dynamics due to anchoring of the liquid crystal molecules on the interface. The objective of this study is to demonstrate the consequences of such dynamics in the flow field created by an elongated nematic drop retracting in an isotropic matrix. This is accomplished by two-dimensional flow simulations using a diffuse-interface model. By exploring the coupling among bulk liquid crystal orientation, surface anchoring and the flow field, we show that the anchoring energy plays a fundamental role in the interfacial dynamics of nematic liquids. In particular, it gives rise to a dynamic interfacial tension that depends on the bulk orientation. Tangential gradient of the interfacial tension drives a Marangoni flow near the nematic-isotropic interface. Besides, the anchoring energy produces an additional normal force on the interface that, together with the interfacial tension, determines the movement of the interface. Consequently, a nematic drop with planar anchoring retracts more slowly than a Newtonian drop, while one with homeotropic anchoring retracts faster than a Newtonian drop. The numerical results are consistent with prior theories for interfacial rheology and experimental observations.
AB - Nematic-isotropic interfaces exhibit novel dynamics due to anchoring of the liquid crystal molecules on the interface. The objective of this study is to demonstrate the consequences of such dynamics in the flow field created by an elongated nematic drop retracting in an isotropic matrix. This is accomplished by two-dimensional flow simulations using a diffuse-interface model. By exploring the coupling among bulk liquid crystal orientation, surface anchoring and the flow field, we show that the anchoring energy plays a fundamental role in the interfacial dynamics of nematic liquids. In particular, it gives rise to a dynamic interfacial tension that depends on the bulk orientation. Tangential gradient of the interfacial tension drives a Marangoni flow near the nematic-isotropic interface. Besides, the anchoring energy produces an additional normal force on the interface that, together with the interfacial tension, determines the movement of the interface. Consequently, a nematic drop with planar anchoring retracts more slowly than a Newtonian drop, while one with homeotropic anchoring retracts faster than a Newtonian drop. The numerical results are consistent with prior theories for interfacial rheology and experimental observations.
UR - http://www.scopus.com/inward/record.url?scp=23944437416&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=23944437416&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2005.04.018
DO - 10.1016/j.jcis.2005.04.018
M3 - Article
C2 - 16122548
AN - SCOPUS:23944437416
SN - 0021-9797
VL - 290
SP - 281
EP - 288
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
IS - 1
ER -