Study of Self-Propelled Pufferfish Driven by Multiple Fins: A Comparison Between Rigid and Deformable Fins

2017 ◽  
Author(s):  
Ruoxin Li ◽  
Qing Xiao ◽  
Lijun Li ◽  
Hao Liu
Keyword(s):  
Underlying Mechanism ◽  
Operating Conditions ◽  
The Self ◽  
Fish Swimming ◽  
Propulsion Efficiency ◽  
Live Fish ◽  
Body Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Multi Body ◽  
Better Than

In this work, we numerically studied the steady swimming of a pufferfish driven by the undulating motion of its dorsal, anal and caudal fins. The simulations are based on experimentally measured kinematics. To model the self-propelled fish swimming, a Computational Fluid Dynamics (CFD) tool was coupled with a Multi-Body-Dynamics (MBD) technique. It is widely accepted that deformable/flexible or undulating fins are better than rigid fins in terms of propulsion efficiency. To elucidate the underlying mechanism, we established an undulating fins model based on the kinematics of live fish, and conducted a simulation under the same operating conditions as rigid fins. The results presented here agree with this view by showing that the contribution of undulating fins to propulsion efficiency is significantly larger than that of rigid fins.

Would Travel Experiences or Possessions Make People Happier?

2022 ◽  
pp. 004728752110646
Author(s):  
Wan Yang ◽  
Ye Zhang ◽  
Yao-Chin Wang
Keyword(s):  
Experimental Design ◽  
Underlying Mechanism ◽  
The Self ◽  
Consumption Choices ◽  
Better Than

To inform consumption choices bring people greater happiness, it is necessary to identify the types of consumption with greater happiness-generating potential. Using an experimental design, this research demonstrates that tourism experiences tend to cultivate happiness better than possessions, by empirically testing a potential underlying mechanism of such superiority—tourism’s potential to cultivate eudaimonia (i.e., the more enduring form of happiness that accounts for the bigger picture beyond the self) without explicit eudaimonic motives. The mechanism can aid the identification of forms of consumption that maximize happiness. This research makes multi-faceted contributions to the tourism and consumption literature on eudaimonia and happiness promotion, including how its revealed potential in implicitly cultivating eudaimonia renders tourism a better consumption choice than material possessions for happiness maximization. Practically, the study suggests how tourism experiences can be designed and marketed to capitalize on the eudaimonic potential.

An Exploration of a PASSIVE Articulated Fish-Like System

2013 ◽  
Author(s):  
Jianxin Hu ◽  
Qing Xiao ◽  
Vinh Tan Nguyen
Keyword(s):  
Degrees Of Freedom ◽  
Muscle Force ◽  
The Self ◽  
Body System ◽  
Multiple Degrees Of Freedom ◽  
Propulsion Mechanism ◽  
Articulated Model ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Multi Body

This study is aimed to investigate the bio-mimetic swimmer propulsion mechanism with the use of its internal muscle force. A simplified articulated model, with multiple rigid segments connected by the joints (imitating the muscle force), is adopted to represent the real swimmer body. To modeling the problem, a Computational Fluid Dynamics (CFD) method is coupled with the system dynamic equations. Some preliminary results obtained showed that the numerical methods developed are able to predict the self-propelled articulated multi-body system with multiple degrees of freedom.

scholarly journals Numerical Investigation on Handling Stability of a Heavy Tractor Semi-Trailer under Crosswind

2020 ◽  
Vol 10 (11) ◽  
pp. 3672 ◽  
Author(s):  
Qianwen Zhang ◽  
Chuqi Su ◽  
Yi Zhou ◽  
Chengcai Zhang ◽  
Jiuyang Ding ◽  
...  
Keyword(s):  
Lateral Displacement ◽  
Aerodynamic Characteristics ◽  
Lateral Acceleration ◽  
Yaw Rate ◽  
Body Dynamics ◽  
Crosswind Stability ◽  
Computational Fluid Dynamics Cfd ◽  
Multi Body ◽  
The Relationship ◽  
Lateral Area

Due to the large lateral area of the trailer and variable road conditions, the handling stability of a heavy tractor semi-trailer under crosswind is very important for road safety. In this present work, numerical simulation is performed to study the crosswind effects on handling stability of a tractor semi-trailer. The aerodynamic characteristics of the tractor semi-trailer under different crosswind were computed by computational fluid dynamics (CFD). Then, mathematical models to reveal the relationship between the aerodynamic forces and crosswind were constructed to serve as inputs of the multi-body dynamics to analyze the handling stability under crosswind. The performance of crosswind stability is evaluated by the response of lateral acceleration, yaw rate and the lateral displacement. The lateral acceleration and yaw rate were decreased by a maximum of 14.6% and 16.5% compared to the truck without the deflector, which showed that the crosswind aerodynamics and stability were obviously improved.

Time-Accurate Simulation of Longitudinal Flight Mechanics with Control by CFD/RBD Coupling

2012 ◽  
Vol 226-228 ◽  
pp. 788-792 ◽  
Author(s):  
Dong Guo ◽  
Min Xu ◽  
Shi Lu Chen
Keyword(s):  
Computational Study ◽  
Rigid Motion ◽  
Rigid Body Dynamics ◽  
Flight Mechanics ◽  
Control Surface ◽  
Free Flight ◽  
Body Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Coupled Solution ◽  
Surface Deflections

This paper describes a multidisciplinary computational study undertaken to compute the flight trajectories and simultaneously predict the unsteady free flight aerodynamics of aircraft in time domain using an advanced coupled computational fluid dynamics (CFD)/rigid body dynamics (RBD) technique. This incorporation of the flight mechanics equations and controller into the CFD solver loop and the treatment of the mesh, which must move with both the control surface deflections and the rigid motion of the aircraft, are illustrated. This work is a contribution to a wider effort towards the simulation of aeroelastic and flight stability in regions where nonlinear aerodynamics, and hence potentially CFD, can play a key role. Results demonstrating the coupled solution are presented.

scholarly journals Classical gravitational self-energy from double copy

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Gabriel Luz Almeida ◽  
Stefano Foffa ◽  
Riccardo Sturani
Keyword(s):  
Gravitational Field ◽  
Binary System ◽  
The Self ◽  
Gravitational Coupling ◽  
Leading Order ◽  
Body System ◽  
Self Energy ◽  
Composite Systems ◽  
Body Dynamics ◽  
Double Copy

Abstract We apply the classical double copy to the calculation of self-energy of composite systems with multipolar coupling to gravitational field, obtaining next-to-leading order results in the gravitational coupling GN by generalizing color to kinematics replacement rules known in literature. When applied to the multipolar description of the two-body system, the self-energy diagrams studied in this work correspond to tail processes, whose physical interpretation is of radiation being emitted by the non-relativistic source, scattered by the curvature generated by the binary system and then re-absorbed by the same source. These processes contribute to the conservative two-body dynamics and the present work represents a decisive step towards the systematic use of double copy within the multipolar post-Minkowskian expansion.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

Sir Robert Stawell Ball and methodologies of modern screw theory

2002 ◽  
Vol 216 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H Lipkin ◽  
J Duffy
Keyword(s):  
Computational Geometry ◽  
Rigid Body ◽  
Lie Algebra ◽  
Screw Theory ◽  
Mechanical Design ◽  
Ball Screw ◽  
Dual Numbers ◽  
Body Dynamics ◽  
Rigid Body Mechanics ◽  
Multi Body

The theory of screws was largely developed by Sir Robert Stawell Ball over 100 years ago to investigate general problems in rigid body mechanics. Nowadays, screw theory is applied in many different but related forms including dual numbers, Plilcker coordinates and Lie algebra. An overview of these methodologies is presented along with a perspective on Ball. Screw theory has re-emerged after a hiatus to become an important tool in robot mechanics, mechanical design, computational geometry and multi-body dynamics.

SOCIAL LOAFING AND SELF-BELIEFS: PEOPLE'S COLLECTIVE EFFORT DEPENDS ON THE EXTENT TO WHICH THEY DISTINGUISH THEMSELVES AS BETTER THAN OTHERS

1998 ◽  
Vol 26 (4) ◽  
pp. 329-340 ◽  
Author(s):  
Emmanuelle Charbonnier ◽  
Pascal Huguet ◽  
Markus Brauer ◽  
Jean-Marc Monteil
Keyword(s):  
Social Life ◽  
The Self ◽  
Social Loafing ◽  
Significant Component ◽  
Easy Task ◽  
Collective Effort ◽  
Better Than

An experiment tested whether the belief that one is better than others on performance aspects of the self moderates social loafing, the tendency for individuals to expend less effort when working collectively than when working individually. French students performed an easy task either coactively or collectively. They were then asked to rate how they individuate themselves from others on personal abilities within various domains of social life. The loafing effect was especially strong in participants who perceived themselves as better than others, suggesting that self-beliefs related to one's feeling of uniqueness is a significant component of social loafing. This finding is discussed from the perspective of Karau and Williams' (1993) Collective Effort Model.

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