Hydrodynamic Oscillations And Tunable Swimming Speed In Squirmers Close To Repulsive Walls

Our model is also applied to calculate the swim pressure in the system, which approaches the previously proposed ideal-gas behavior in wide channels but is found to decrease in narrow channels as a result of confinement. All these activities will result in you needing different types of swim trunks. Significant increases in maneuverability, however, can result from constructing systems without these constraints, rather than violating them. Very little work, however, has been done on modular and self-reconfigurable robots in aquatic applications. In this work, we present a mechanism and strategy that allows a Modboat to dock to/undock from other units without additional actuation. The top body is larger and contains the control hardware; it is the primary body of the Modboat. Four permanent magnets are therefore placed at the four cardinal points inside the top body, as shown in Fig. 1. This allows the circular Modboat to form a square lattice when docked.

Inertial control methods developed in prior work can successfully drive the Modboat along trajectories and enable docking to neighboring modules, but have a non-constant cycle time and cannot react to dynamic environments. The translational dynamics of the Modboat are complex, so we omit them here. There are several methods exploited by microorganisms to cope with environments dominated by viscosity. At faster rotation rates, significant defect elongation and local changes in viscosity allow the swimming direction to be tuned for path planning. Eq. (5) causes the paddling direction to cancel the disturbance and return to the desired heading. This equates the average orientation and the direction of travel, so (2) is sufficient to effectively drive the robot in the plane. Modboat, defined at discrete time intervals as the average orientation over a cycle. Inertial control has more authority but a non-constant cycle time; this makes coordinating tasks or responding to dynamic environments challenging. Dynamic properties of these steady states.

Then, cells at the interface slowly self-organize into a steady state after a relaxation period about several thousand seconds, cf. N is the total number of observed cells. A number of oscillating control laws have been considered for foil-shaped robots. Our results further imply that the existence and extent of steric or electrostatic repulsion of the wall could be tuned to control properties such as the number density and swim speed of active particles near a surface. Since the continuum description with odd-elasticity coarse grains relies on sub-scale active mechanisms, the current study provides general features of the microscopic noisy elastohydrodynamics and therefore will be useful in modeling, understanding, and designing biological and artificial active materials. In contrast, our aim is to seek general features of elastohydrodynamics of an odd-elastic filament as a coarse-grained continuum description of internal activity. Moreover, formula (9) notably holds for any dimensions of shape space as well as of physical space; hence, the results presented in this study, while mainly implemented for the Purcell’s swimmer here, are remarkably generalizable to a wide class of low-Reynolds-number elastohydrodynamics. By examining both systems bounded by confining walls and ones with periodic boundary conditions, we show that finite-size effects are consistent in both cases with the behavior expected for a rarefied thermal gas.

In turn, if we further add thermal fluctuations, the odd-elastic swimmer can be represented as an active rotational Brownian particle with swimming velocity given by (9), and angle diffusion from the thermal noise. Suggest the possibility to use hydrodynamic flow for self-assembly in active matter. Current active matter research focuses primarily on linearly swimming particles which have a symmetric body and self-propel along one of the symmetry axes. Hyperuniformity (43, 44) has been considered as a new form of material order which leads to novel functionalities (45, 46, 47, 48, 49); it has been observed in many systems, including avian photoreceptor patterns (50), amorphous ices (51), amorphous silica (52), ultracold atoms (53), soft matter systems (54, 55, 56, 57, 58, 59, 60, 61), and stochastic models (62, 63, 64). Our work demonstrates the existence of hyperuniformity in active matter. Deviation from such a perfect alignment leads to a persistent curvature in the microswimmer trajectories; examples of such circle microswimmers include anisotropic artificial micromotors (27, 28), self-propelled nematic droplets (29, 30), magnetotactic bacteria and Janus particles in rotating external fields (31, 32), Janus particle in viscoelastic medium (33), sperm and bacteria near interfaces (34, 35). Chiral motility of circle microswimmers, as predicted by theoretical and numerical investigations, can lead to a range of interesting collective phenomena in circular microswimmers, including vortex structures (36, 37), goggle strap localization in traps (38), enhanced flocking (39), and hyperuniform states (40). However, experimental verifications of these predictions are limited (35, 32), a situation mainly due to the scarcity of suitable experimental systems.

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