scholarly journals Hydrodynamics can determine the optimal route for microswimmer navigation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Abdallah Daddi-Moussa-Ider ◽  
Hartmut Löwen ◽  
Benno Liebchen
Keyword(s):  
Flow Field ◽  
Hydrodynamic Interactions ◽  
Optimal Trajectories ◽  
Optimal Route ◽  
Active Particles ◽  
Navigation Strategy ◽  
Navigation Strategies

AbstractAs compared to the well explored problem of how to steer a macroscopic agent, like an airplane or a moon lander, to optimally reach a target, optimal navigation strategies for microswimmers experiencing hydrodynamic interactions with walls and obstacles are far-less understood. Here, we systematically explore this problem and show that the characteristic microswimmer-flow-field crucially influences the navigation strategy required to reach a target in the fastest way. The resulting optimal trajectories can have remarkable and non-intuitive shapes, which qualitatively differ from those of dry active particles or motile macroagents. Our results provide insights into the role of hydrodynamics and fluctuations on optimal navigation at the microscale, and suggest that microorganisms might have survival advantages when strategically controlling their distance to remote walls.

scholarly journals Clustering and phase behaviour of attractive active particles with hydrodynamics

Soft Matter ◽  
2015 ◽  
Vol 11 (38) ◽  
pp. 7525-7546 ◽  
Author(s):  
Ricard Matas Navarro ◽  
Suzanne M. Fielding
Keyword(s):  
Phase Separation ◽  
Thermodynamic Temperature ◽  
Equilibrium Temperature ◽  
Phase Behaviour ◽  
Hydrodynamic Interactions ◽  
Attractive Potential ◽  
Passive System ◽  
Active Particles ◽  
Level Of Activity

The level of activity relative to the strength of attraction plays the role of an effective non-equilibrium temperature, counterpart to the thermodynamic temperature in the passive system. Even in the presence of an attractive potential, hydrodynamic interactions strongly suppress motility induced phase separation.

Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Guide Vane ◽  
Flow Measurements ◽  
Vast Number ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

The vast number of turbine cascade studies in the literature has been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling at these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall.

Dynamics of polymers in solution: the role of time-dependent hydrodynamic interactions

1991 ◽  
Vol 24 (22) ◽  
pp. 5997-6005 ◽  
Author(s):  
J. Bonet Avalos ◽  
J. M. Rubi ◽  
D. Bedeaux
Keyword(s):  
Time Dependent ◽  
Hydrodynamic Interactions

scholarly journals Role of Transient Characteristics in Fish Trajectory Modeling

2020 ◽  
Author(s):  
zhu gao ◽  
zu hao zhou ◽  
Helge I Andersson
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Turbulent Flow ◽  
Transient Flow ◽  
Simultaneous Recording ◽  
Fish Locomotion ◽  
Vertical Slot ◽  
Turbulent Flow Structure ◽  
General Method

In this paper, we analyzed the live fish trajectory recorded from an experiment in an experimental vertical slot fishway. Combined with a numerical simulation, we demonstrated that randomness shown in fish trajectory might not merely be attributed to fish's random choices in its swimming, also could be an adaption consequence to the bulk unsteady turbulent flow structure. Simple superposing the fish trajectory on the time-averaged flow field obtained either by interpolating on discrete point measurements or numerical simulation is not an ideal method for fish movement description in fishway engineering. How to model the fish paths in transient flow and the necessity of simultaneous recording of the flow field and the fish locomotion are challenging topics. The suggested spectrum analysis of the flow field may provide a new general method to reproduce the fish trajectory in a complex turbulent flow.

The Role of Vortices and Unsteady Effects During the Hovering Flight of Dragonflies

1979 ◽  
Vol 83 (1) ◽  
pp. 59-77 ◽  
Author(s):  
STUART B. SAVAGE ◽  
BARRY G. NEWMAN ◽  
DENIS T.-M. WONG
Keyword(s):  
Steady State ◽  
Flow Field ◽  
Flow Visualization ◽  
Inviscid Flow ◽  
Physical Explanation ◽  
Hovering Flight ◽  
Wing Motion ◽  
Unsteady Effects ◽  
Animal Flight

Weis-Fogh and Norberg concluded that steady-state aerodynamics is incapable of explaining how the dragonfly supports its weight during hovering. Norberg also concluded that the wing kinematics of Aeschna juncea L., as determined photographically, are incompatible with those proposed by Weis-Fogh for his Flip mechanism. The present paper has proposed an alternative lift-generating mechanism, various aspects of which are novel from the standpoint of animal flight. Flow visualization tests performed in water established the flow field during a complete cycle of the idealized wing motion. Using this information and unsteady inviscid flow theory the forces were analysed. A plausible balance of horizontal forces and more than sufficient lift were obtained. A physical explanation of the theory is provided for those who do not wish to study the mathematical details.

scholarly journals Role of Transient Characteristics in Fish Trajectory Modeling

2020 ◽  
Vol 12 (17) ◽  
pp. 6765
Author(s):  
Gao Zhu ◽  
Zuhao Zhou ◽  
Helge I Andersson
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Transient Flow ◽  
Silver Carp ◽  
Simultaneous Recording ◽  
Trajectory Modeling ◽  
Fish Locomotion ◽  
Vertical Slot ◽  
Ideal Method

In this experiment, we analyzed live fish (silver carp) trajectories recorded in an experimental vertical-slot fishway. Combined with a numerical simulation, we demonstrated that randomness shown in fish trajectories might not merely be attributed to the fish’s random choices in its swimming, but could also be a consequence of adaption to the bulk unsteady turbulent flow structures. Simple superposition of a fish trajectory on the time-averaged flow field obtained either by interpolating on discrete point measurements or numerical simulation data is not an ideal method for description of fish movement. How to model the fish paths in transient flow and the necessity of simultaneous recording of the flow field and the fish locomotion are challenging topics. We also discussed the possible integration of currently existing methods to promote the development of fish trajectory modeling.

scholarly journals How Much Information Does a Robot Need? Exploring the Benefits of Increased Sensory Range in a Simulated Crowd Navigation Task

Information ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 112
Author(s):  
Marit Hagens ◽  
Serge Thill
Keyword(s):  
Task Performance ◽  
Human Robot Interaction ◽  
The Other ◽  
Proof Of Concept ◽  
Robot Interaction ◽  
Navigation Task ◽  
Navigation Strategy ◽  
Hardware Designs ◽  
Navigation Strategies ◽  
And Task

Perfect information about an environment allows a robot to plan its actions optimally, but often requires significant investments into sensors and possibly infrastructure. In applications relevant to human–robot interaction, the environment is by definition dynamic and events close to the robot may be more relevant than distal ones. This suggests a non-trivial relationship between sensory sophistication on one hand, and task performance on the other. In this paper, we investigate this relationship in a simulated crowd navigation task. We use three different environments with unique characteristics that a crowd navigating robot might encounter and explore how the robot’s sensor range correlates with performance in the navigation task. We find diminishing returns of increased range in our particular case, suggesting that task performance and sensory sophistication might follow non-trivial relationships and that increased sophistication on the sensor side does not necessarily equal a corresponding increase in performance. Although this result is a simple proof of concept, it illustrates the benefit of exploring the consequences of different hardware designs—rather than merely algorithmic choices—in simulation first. We also find surprisingly good performance in the navigation task, including a low number of collisions with simulated human agents, using a relatively simple A*/NavMesh-based navigation strategy, which suggests that navigation strategies for robots in crowds need not always be sophisticated.

scholarly journals Unravelling the role of phoretic and hydrodynamic interactions in active colloidal suspensions

Soft Matter ◽  
2020 ◽  
Vol 16 (38) ◽  
pp. 8893-8903
Author(s):  
Andrea Scagliarini ◽  
Ignacio Pagonabarraga
Keyword(s):  
Colloidal Suspensions ◽  
Hydrodynamic Interactions ◽  
Aggregation Kinetics ◽  
Cluster Growth ◽  
Cluster Morphology

We study numerically suspensions of self-diffusiophoretic colloids for various colloid–solute affinities. We show that hydrodynamics affects the aggregation kinetics and the cluster morphology, significantly hindering cluster growth.

Sign in / Sign up

Export Citation Format

Share Document