| The non-equilibrium self-organization of self-propelled system is widely observed in nature.In last several decades,physicist has done intensive theoretical and simulation study to investigate the self-organization in self-propelled systems.However,we still lack a coherent understanding of the principle of non-equilibrium self-organization.With the recent development of colloidal science,it is now popular to study the non-equilibrium self-organization in self-propelled colloidal system.More importantly,self-propelled colloidal system can also exhibit the collective motion as observed in biological swarming.Colloidal system facilitates the study of collective behavior and the dynamic process in collective motion.In this thesis,we mainly discuss about the kinetics of self-propelled colloidal particles.We briefly introduced the relationship between electrode voltage,particle density and velocity,and gave some simple explanation.On this basis,we studied the transition to collective motion in such self-propelled colloidal system.We examined how the activity ratio,density fluctuation,particle velocity depend on time and voltage.In order to understand the behavior of single particles and the relationship between single particle motion and collective motion,we study the collective behavior of selfdriven colloidal system under electric field.The results show that the velocity of a single particle depends on the electric field,and the velocity in the collective motion is higher than that of the individual particles,which is a result of the fluid and the interaction between the particles.In the study of the transition into collective motion,we changed voltage to switch on and off the particle motion,and studied the consequent collective dynamic process.In the meantime,we found that the transition between collective motion and static state has hysteresis effect.We also briefly discussed the existing questions and the future direction on the study of collective motion using colloidal systems. |
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