Nonequilibrium Dynamics of a Magnetic Nanocapsule in a Nematic Liquid Crystal

Abstract

Colloidal particles in nematic liquid crystals show a beautiful variety of complex phenomena with promising applications. Their dynamical behaviour is determined by topology and interactions with the liquid crystal and external fields. Here, a nematic magnetic nanocapsule reoriented periodically by time-varying magnetic fields is studied using numerical simulations. The approach combines Molecular Dynamics to resolve solute–solvent interactions and Nematic Multiparticle Collision Dynamics to incorporate nematohydrodynamic fields and fluctuations. A Saturn ring defect resulting from homeotropic anchoring conditions surrounds the capsule and rotates together with it. Magnetically induced rotations of the capsule can produce transformations of this topological defect, which changes from a disclination curve to a defect structure extending over the surface of the capsule. Transformations occur for large magnetic fields. At moderate fields, elastic torques prevent changes of the topological defect by tilting the capsule out from the rotation plane of the magnetic field.

Lock-key microfluidics: simulating nematic colloid advection along wavy-walled channels

“…Rotations due to flows: the nematodynamic response models the nematogens' response to velocity gradients through Jeffery's equation where g R is a rotational friction coefficient. 64,67,69 By choosing a sufficiently small value of g R backflow effects can be kept small, even in the limit of small Ericksen numbers.…”

“…[61][62][63] Most relevantly, MPCD has been used to simulate nematic liquid crystals. 64 In this context, MPCD has simulated nematohydrodynamics, 65 suspended colloids, 66,67 magnetic colloids, 68,69 living liquid crystals, 70 and active nematics. [71][72][73] For the present study, MPCD is chosen because it is ideal for moderate Pe ´clet numbers, mobile solutes and complex boundaries.…”

“…Finally, director dynamics are coupled back to the velocity field through local torques parameterized by a rotational mobility coefficient g R (see Appendix A for details). 64,69 A small value is chosen to keep backflow effects to a minimum. Numerical analysis has shown that N-MPCD describes a linearized nematohydrodynamic model in which viscosity and elastic effects are isotropic.…”

“…The director dynamics are coupled back to the velocity field through the change in angular momentum , where γ R is a rotational friction coefficient. 64,67,69 By choosing a sufficiently small value of γ R backflow effects can be kept small, even in the limit of small Ericksen numbers.…”

Updates in Prevalence, Risk Factors, Management and Outcome of Treatment of Acute Pancreatitis

“…Regardless of these fluctuations, there remains to be an agreement on the rank and vital of durable early fluid recovery [32] Several sorts of fluids are presently used for fluid resuscitation, which mainly comprises crystalloid and colloidal keys. With an increased risk of mortality and kidney failure needful renal replacement treatment has been observed when using hydroxyethyl arrowroot instead of crystalloid solution [33]. At present, the use of crystal fluids for fluid revival is usually preferred, with colloidal fluids playing an auxiliary part [34].…”