Onsager's variational principle in active soft matter

TY - JOUR

T1 - Onsager's variational principle in active soft matter

AU - Wang, Haiqin

AU - Qian, Tiezheng

AU - Xu, Xinpeng

N1 - Publisher Copyright: © The Royal Society of Chemistry 2021.

PY - 2021/4/7

Y1 - 2021/4/7

N2 - Onsagers variational principle (OVP) was originally proposed by Lars Onsager in 1931 [L. Onsager,Phys. Rev., 1931,37, 405]. This fundamental principle provides a very powerful tool for formulating thermodynamically consistent models. It can also be employed to find approximate solutions, especially in the study of soft matter dynamics. In this work, OVP is extended and applied to the dynamic modeling of active soft matter such as suspensions of bacteria and aggregates of animal cells. We first extend the general formulation of OVP to active matter dynamics where active forces are included as external non-conservative forces. We then use OVP to analyze the directional motion of individual active units: a molecular motor walking on a stiff biofilament and a toy two-sphere microswimmer. Next we use OVP to formulate a diffuse-interface model for an active polar droplet on a solid substrate. In addition to the generalized hydrodynamic equations for active polar fluids in the bulk region, we have also derived thermodynamically consistent boundary conditions. Finally, we consider the dynamics of a thin active polar droplet under the lubrication approximation. We use OVP to derive a generalized thin film equation and then employ OVP as an approximation tool to find the spreading laws for the thin active polar droplet. By incorporating the activity of biological systems into OVP, we develop a general approach to construct thermodynamically consistent models for better understanding the emergent behaviors of individual animal cells and cell aggregates or tissues.

AB - Onsagers variational principle (OVP) was originally proposed by Lars Onsager in 1931 [L. Onsager,Phys. Rev., 1931,37, 405]. This fundamental principle provides a very powerful tool for formulating thermodynamically consistent models. It can also be employed to find approximate solutions, especially in the study of soft matter dynamics. In this work, OVP is extended and applied to the dynamic modeling of active soft matter such as suspensions of bacteria and aggregates of animal cells. We first extend the general formulation of OVP to active matter dynamics where active forces are included as external non-conservative forces. We then use OVP to analyze the directional motion of individual active units: a molecular motor walking on a stiff biofilament and a toy two-sphere microswimmer. Next we use OVP to formulate a diffuse-interface model for an active polar droplet on a solid substrate. In addition to the generalized hydrodynamic equations for active polar fluids in the bulk region, we have also derived thermodynamically consistent boundary conditions. Finally, we consider the dynamics of a thin active polar droplet under the lubrication approximation. We use OVP to derive a generalized thin film equation and then employ OVP as an approximation tool to find the spreading laws for the thin active polar droplet. By incorporating the activity of biological systems into OVP, we develop a general approach to construct thermodynamically consistent models for better understanding the emergent behaviors of individual animal cells and cell aggregates or tissues.

UR - http://www.scopus.com/inward/record.url?scp=85103905829&partnerID=8YFLogxK

U2 - 10.1039/d0sm02076a

DO - 10.1039/d0sm02076a

M3 - 文章

C2 - 33480912

AN - SCOPUS:85103905829

SN - 1744-683X

VL - 17

SP - 3634

EP - 3653

JO - Soft Matter

JF - Soft Matter

IS - 13

ER -