arXiv subjects

Akira Kobayashi

Publications and source records attributed to Akira Kobayashi.

4 recordsLinked to original sources

arXiv2023

Odd elasticity of a catalytic micromachine

We perform numerical simulations of a model micromachine driven by catalytic chemical reactions. Our model includes a mechano-chemical coupling between the structural variables and the nonequilibrium variable describing the catalytic reactions. The time-correlation functions of the structural variables are calculated and further analyzed in terms of odd Langevin dynamics. We obtain the effective odd elastic constant that manifests the broken time-reversal symmetry of a catalytic micromachine. Within the simulation, we separately estimate the quantity called nonreciprocality and show that its behavior is similar to that of the odd elasticity.Our approach suggests a new method to extract the nonequilibrium properties of a micromachine only by measuring its structural dynamics.

cond-mat.soft↗

arXiv2023

Simulations of Odd Microswimmers

We perform numerical simulations of odd microswimmers consisting of three spheres and two odd springs. To describe the hydrodynamic interaction, both the Oseen-type and the Rotne-Prager-Yamakawa (RPY)-type mobilities are used. For the Oseen-type mobility, the simulation results quantitatively reproduce the asymptotic expression of the average velocity. For the RPY-type mobility, on the other hand, the average velocity is smaller than that of the Oseen-type mobility and the deviation is more pronounced for larger spheres. We also perform simulations of microswimmers having different sphere sizes and show that the average velocity becomes smaller than that of the equal size case. The size of the middle sphere plays an important role in determining the average velocity.

cond-mat.soft↗

arXiv2022

Time-correlation functions for odd Langevin systems

We investigate the statistical properties of fluctuations in active systems that are governed by non-symmetric responses. Both an underdamped Langevin system with an odd resistance tensor and an overdamped Langevin system with an odd elastic tensor are studied. For a system in thermal equilibrium, the time-correlation functions should satisfy time-reversal symmetry and the anti-symmetric parts of the correlation functions should vanish. For the odd Langevin systems, however, we find that the anti-symmetric parts of the time-correlation functions can exist and that they are proportional to either the odd resistance coefficient or the odd elastic constant. This means that the time-reversal invariance of the correlation functions is broken due to the presence of odd responses in active systems. Using the short-time asymptotic expressions of the time-correlation functions, one can estimate an odd elastic constant of an active material such as an enzyme or a motor protein.

cond-mat.soft↗

arXiv2021

The Onsager-Machlup Integral for Non-reciprocal Systems with Odd Elasticity

The variational principle of the Onsager-Machlup integral is used to describe the stochastic dynamics of a micromachine, such as an enzyme, characterized by odd elasticity. The obtained most probable path is found to become non-reciprocal in the presence of odd elasticity and is further related to the entropy production.

cond-mat.soft↗