scholarly journals Friction modulation in limbless, three-dimensional gaits and heterogeneous terrains

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaotian Zhang ◽  
Noel Naughton ◽  
Tejaswin Parthasarathy ◽  
Mattia Gazzola
Keyword(s):  
Engineering Design ◽  
Three Dimensional ◽  
Surface Friction ◽  
Friction Modeling ◽  
Interfacial Effects ◽  
3D Simulations ◽  
Unified View ◽  
Solid Obstacles ◽  
Limbless Locomotion ◽  
Effective Friction

AbstractMotivated by a possible convergence of terrestrial limbless locomotion strategies ultimately determined by interfacial effects, we show how both 3D gait alterations and locomotory adaptations to heterogeneous terrains can be understood through the lens of local friction modulation. Via an effective-friction modeling approach, compounded by 3D simulations, the emergence and disappearance of a range of locomotory behaviors observed in nature is systematically explained in relation to inhabited environments. Our approach also simplifies the treatment of terrain heterogeneity, whereby even solid obstacles may be seen as high friction regions, which we confirm against experiments of snakes ‘diffracting’ while traversing rows of posts, similar to optical waves. We further this optic analogy by illustrating snake refraction, reflection and lens focusing. We use these insights to engineer surface friction patterns and demonstrate passive snake navigation in complex topographies. Overall, our study outlines a unified view that connects active and passive 3D mechanics with heterogeneous interfacial effects to explain a broad set of biological observations, and potentially inspire engineering design.

3D simulations of warm and hot Jupiter atmospheres: the role of 3D mixing in shaping CH4-to-CO conversion pathways

2021 ◽  
Author(s):  
Maria Zamyatina ◽  
Eric Hebrard ◽  
Nathan Mayne ◽  
Benjamin Drummond
Keyword(s):  
Chemical Structure ◽  
Three Dimensional ◽  
Chemical Species ◽  
Radiation Chemistry ◽  
3D Simulations ◽  
Horizontal Advection ◽  
Co Conversion ◽  
Area Of Influence ◽  
Different Parts

<p>We present results from a set of cloud-free simulations of exoplanet atmospheres using a coupled three-dimensional (3D) hydrodynamics-radiation-chemistry model. We report in particular our investigation of the thermodynamic and chemical structure of the atmospheres of HAT-P-11b and WASP-17b and their comparison with the results for the atmospheres of HD 189733b and HD 209458b presented in Drummond et al. (2020). We found that the abundances of chemical species from simulations with interactive chemistry depart from their respective abundances computed at local chemical equilibrium, especially at higher latitudes. To understand this departure, we analysed the CH<sub>4</sub>-to-CO conversion pathways within the Venot et al. (2019) reduced chemical network used in our model using a chemical network analysis. We found that at steady state nine CH<sub>4</sub>-to-CO conversion pathways manifest in our 3D simulations with interactive chemistry, with different pathways dominating different parts of the atmosphere and their area of influence being determined by the vertical and horizontal advection and shifting between planets.</p>

Shakedown analysis for the evaluation of strength and bearing capacity of multilayered railway structures

2018 ◽  
Vol 232 (9) ◽  
pp. 2324-2335 ◽  
Author(s):  
Kangyu Wang ◽  
Yan Zhuang ◽  
Hanlong Liu
Keyword(s):  
Bearing Capacity ◽  
Engineering Design ◽  
Permanent Deformation ◽  
Three Dimensional ◽  
Frictional Coefficient ◽  
Repeated Loading ◽  
Residual Stress Field ◽  
Shakedown Analysis ◽  
Traffic Loads ◽  
Shakedown Limit

Shakedown analysis is a robust approach for solving the strength problem of a structure under cyclic or repeated loading, e.g. railway structures subject to rolling and sliding traffic loads. Owing to the traffic loads, which are higher than the “shakedown limit”, railway structures may fail due to the excessive permanent deformation. This paper develops the analytical shakedown solutions based on Melan’s shakedown theorem, which is then applied for the evaluation of the strength and bearing capacity of multilayered railway structures. The shakedown solutions utilize the elastic stress fields obtained from the fully three-dimensional finite/infinite model, and calculate the shakedown multiplier for each layer of railway structures by means of a self-equilibrated critical residual stress field. The shakedown limits are then determined as the minimum shakedown multiplier among all layers. Parametric studies are also conducted, which indicate how the frictional coefficient, strength and stiffness of the materials, and the thickness ratio of ballast to subballast influence the shakedown limit and the stability condition of railway structures. The critical points of shakedown occur at the rail for low values of rail’s yield stress and large frictional coefficient, while they occur at the ballast layer when the frictional coefficient is relatively small. The shakedown limits are found to decrease with the increase in the strength and thickness of the ballast for a relatively small frictional coefficient. For the engineering design, there is an optimum combination of material properties and layer thickness, which provides the maximum bearing capacity of the railway structure based on this research. The results obtained from this study can provide a useful reference for the engineering design of railway structures.

scholarly journals Modelling the 3D climate of Venus with oasis

2020 ◽  
Vol 496 (3) ◽  
pp. 3512-3530
Author(s):  
João M Mendonça ◽  
Lars A Buchhave
Keyword(s):  
Observational Data ◽  
Surface Soil ◽  
Surface Friction ◽  
3D Models ◽  
Terrestrial Planets ◽  
3D Simulations ◽  
Planetary Environments ◽  
Atmospheric Heat ◽  
Physical And Chemical ◽  
Observational Techniques

ABSTRACT Flexible 3D models to explore the vast diversity of terrestrial planets and interpret observational data are still in their early stages. In this work, we present oasis: a novel and flexible 3D virtual planet laboratory. With oasis we envision a platform that couples self-consistently seven individual modules representing the main physical and chemical processes that shape planetary environments. Additionally, oasis is capable of producing simulated spectra from different instruments and observational techniques. In this work, we focus on the benchmark test of coupling four of the physical modules: fluid dynamics, radiation, turbulence, and surface/soil. To test the oasis platform, we produced 3D simulations of the Venus climate and its atmospheric circulation and study how the modelled atmosphere changes with various cloud covers, atmospheric heat capacity, and surface friction. 3D simulations of Venus are challenging because they require long integration times with a computationally expensive radiative transfer code. By comparing oasis results with observational data, we verify that the new model is able to successfully simulate Venus. With simulated spectra produced directly from the 3D simulations, we explore the capabilities of future missions, like LUVOIR, to observe Venus analogues located at a distance of 10 pc. With oasis, we have taken the first steps to build a sophisticated and very flexible platform capable of studying the environment of terrestrial planets, which will be an essential tool to characterize observed terrestrial planets and plan future observations.

Regimes of Dry Convection above Wildfires: Sensitivity to Fire Line Details

2010 ◽  
Vol 67 (3) ◽  
pp. 611-632 ◽  
Author(s):  
Michael T. Kiefer ◽  
Matthew D. Parker ◽  
Joseph J. Charney
Keyword(s):  
Line Shape ◽  
3D Model ◽  
Three Dimensional ◽  
Vertical Wind Shear ◽  
Heating Rates ◽  
3D Simulations ◽  
Complex Phenomena ◽  
2D And 3D ◽  
The Impact ◽  
Dry Convection

Abstract Fire lines are complex phenomena with a broad range of scales of cross-line dimension, undulations, and along-line variation in heating rates. While some earlier studies have examined parcel processes in two-dimensional simulations, the complexity of fire lines in nature motivates a study in which the impact of three-dimensional fire line details on parcel processes is examined systematically. This numerical modeling study aims to understand how fundamental processes identified in 2D simulations operate in 3D simulations where the fire line is neither straight nor uniform in intensity. The first step is to perform simulations in a 3D model, with no fire line undulations or inhomogeneity. In general, convective modes simulated in the 2D model are reproduced in the 3D model. In one particular case with strong vertical wind shear, new convection develops separate from the main line of convection as a result of local changes to parcel speed and heating. However, in general the processes in the 2D and 3D simulations are identical. The second step is to examine 3D experiments wherein fire line shape and along-line inhomogeneity are varied. Parcel heating, as well as convective mode, is shown to exhibit sensitivity to fire line shape and along-line inhomogeneity.

scholarly journals Solid-Liquid Interfacial Effects on Residual Oil Distribution Utilizing Three-Dimensional Micro Network Models

Energies ◽  
2017 ◽  
Vol 10 (12) ◽  
pp. 2059 ◽  
Author(s):  
Weiyao Zhu ◽  
Bingbing Li ◽  
Yajing Liu ◽  
Hongqing Song ◽  
Xiaofeng Wang
Keyword(s):  
Three Dimensional ◽  
Network Models ◽  
Residual Oil ◽  
Interfacial Effects ◽  
Oil Distribution ◽  
Solid Liquid

An unified view of the spin dynamics in two- and three-dimensional magnetic systems

1999 ◽  
Vol 205 (2-3) ◽  
pp. 343-356 ◽  
Author(s):  
U. Köbler ◽  
A. Hoser ◽  
M. Kawakami ◽  
T. Chatterji ◽  
J. Rebizant
Keyword(s):  
Spin Dynamics ◽  
Three Dimensional ◽  
Magnetic Systems ◽  
Unified View

scholarly journals The Dynamic Three-Dimensional Localization of Fields in Active Percolating Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Gennadiy Burlak
Keyword(s):  
Fractal Dimension ◽  
Nonlinear System ◽  
Three Dimensional ◽  
Percolation Cluster ◽  
Localized States ◽  
3D Simulations ◽  
Localized Solutions ◽  
Anisotropic Inhomogeneity

We study a dynamic three-dimensional (3D) field localized states in a medium with percolation disorder, where the percolation cluster is filled by the active nanoemitters. In such a system, the incipient percolating cluster generates a fractal radiating structure in which the field is radiated and scattered by the anisotropic inhomogeneity. Our numerical 3D simulations show that such a nonlinear system with noninteger fractal dimension has well-defined localized solutions for fields (3D speckles). The statistics of speckles is studied too.

A facile method for the preparation of three-dimensional CNT sponge and a nanoscale engineering design for high performance fiber-shaped asymmetric supercapacitors

2017 ◽  
Vol 5 (43) ◽  
pp. 22559-22567 ◽  
Author(s):  
Yong Li ◽  
Zhuo Kang ◽  
Xiaoqin Yan ◽  
Shiyao Cao ◽  
Minghua Li ◽  
...  
Keyword(s):  
Engineering Design ◽  
High Performance ◽  
Three Dimensional ◽  
Wearable Electronics ◽  
Asymmetric Supercapacitors ◽  
Smart Textiles ◽  
High Performance Fiber ◽  
Application Potential

Fiber supercapacitors (FSCs) have great application potential in future smart textiles and portable and wearable electronics because of their flexibility, tiny volume and wearability.

Spectral Retrieval of Latent Heating Profiles from TRMM PR Data. Part IV: Comparisons of Lookup Tables from Two- and Three-Dimensional Cloud-Resolving Model Simulations

2009 ◽  
Vol 22 (20) ◽  
pp. 5577-5594 ◽  
Author(s):  
Shoichi Shige ◽  
Yukari N. Takayabu ◽  
Satoshi Kida ◽  
Wei-Kuo Tao ◽  
Xiping Zeng ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Latent Heating ◽  
3D Simulations ◽  
Toga Coare ◽  
Trmm Pr ◽  
Lookup Tables ◽  
Cloud Resolving Model ◽  
Heating Profiles ◽  
Maximum Heating ◽  
Melting Level

Abstract The spectral latent heating (SLH) algorithm was developed to estimate latent heating profiles for the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR). The method uses TRMM PR information (precipitation-top height, precipitation rates at the surface and melting level, and rain type) to select heating profiles from lookup tables (LUTs). LUTs for the three rain types—convective, shallow stratiform, and anvil rain (deep stratiform with a melting level)—were derived from numerical simulations of tropical cloud systems from the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) using a cloud-resolving model (CRM). The two-dimensional (2D) CRM was used in previous studies. The availability of exponentially increasing computer capabilities has resulted in three-dimensional (3D) CRM simulations for multiday periods becoming increasingly prevalent. In this study, LUTs from the 2D and 3D simulations are compared. Using the LUTs from 3D simulations results in less agreement between the SLH-retrieved heating and sounding-based heating for the South China Sea Monsoon Experiment (SCSMEX). The level of SLH-estimated maximum heating is lower than that of the sounding-derived maximum heating. This is explained by the fact that using the 3D LUTs results in stronger convective heating and weaker stratiform heating above the melting level than is the case if using the 2D LUTs. More condensate is generated in and carried from the convective region in the 3D model than in the 2D model, and less condensate is produced by the stratiform region’s own upward motion.

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