arXiv subjects

Hiraku Nishimori

Publications and source records attributed to Hiraku Nishimori.

23 records · Page 2Linked to original sources

arXiv2010

3D Dune Skeleton Model as a Coupled Dynamical System of 2D Cross-Sections

To analyze theoretically the stability of the shape and the migration process of transverse dunes and barchans, we propose a {\it skeleton model} of 3D dunes described with coupled dynamics of 2D cross-sections. First, 2D cross-sections of a 3D dune parallel to the wind direction are extracted as elements of a skeleton of the 3D dune, hence, the dynamics of each and interaction between them is considered. This model simply describes the essential dynamics of 3D dunes as a system of coupled ordinary differential equations. Using the model we study the stability of the shape of 3D transversal dunes and their deformation to barchans depending on the amount of available sand in the dune field, sand flow in parallel and perpendicular to wind direction.

nlin.PS↗

arXiv2010

Counter Chemotactic Flow in Quasi-One-Dimensional Path

Quasi-one-dimensional bidirectional particle flow including the effect of chemotaxis is investigated through a modification of the John-Schadschneider-Chowdhury-Nishinari model. Specifically, we permit multiple lanes to be shared by both directionally traveling particles. The relation between particle density and flux is studied for several evaporation rates of pheromone, and the following results are obtained: i) in the low-particle-density range, the flux is enlarged by pheromone if the pheromone evaporation rate is sufficiently low, ii) in the high particle-density range, the flux is largest at a reasonably high evaporation rate and, iii) if the evaporation rate is at the level intermediate between the above two cases, the flux is kept small in the entire range of particle densities. The mechanism of these behaviors is investigated by observing the spatial-temporal evolution of particles and the average cluster size in the system.

nlin.PS↗

arXiv2004

Collision dynamics of two barchan dunes simulated by a simple model

The collision processes of two crescentic dunes called barchans are systematically studied using a simple computer simulation model. The simulated processes, coalescence, ejection and reorganization, qualitatively correspond to those observed in a water tank experiment. Moreover we found the realized types of collision depend both on the mass ratio and on the lateral distance between barchans under initial conditions. A simple set of differential equations to describe the collision of one-dimensional (1D) dunes is introduced.

cond-mat.soft↗

arXiv2004

Flexible Foraging of Ants under Unsteadily Varying Environment

Using a simple model for the trail formation of ants, the relation between i)the schedule of feeding which represents the unsteady natural environment, ii)emerging patterns of trails connecting a nest with food resources, and iii)the foraging efficiency is studied. Simulations and a simple analysis show that the emergent trail pattern flexibly varies depending on the feeding schedule by which ants can make an efficient foraging according to the underlying unsteady environment.

q-bio.PE↗

arXiv2000

A simple model for the formation of vegetated dunes

A simple model for the dynamics of dunes associated with vegetation is proposed. Using the model, formation processes of transverse dunes, parabolic dunes and elongated parabolic dunes according to two environmental factors: i)the amount of sand at the source, ii)the wind force, are simulated. The results have qualitative correspondence to the real counterpart, and the simplicity of the algorithm and the consequent easiness of the handling of this model provide us with wide applicability for the investigation of the complex interplay between vegetation and dunes.

nlin.PS↗