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Moving mesh methods (also called r-adaptive methods) are space-adaptive strategies used for the numerical simulation of time-dependent partial differential equations. These methods keep the total number of mesh points fixed during the…

Numerical Analysis · Mathematics 2019-07-31 Tomasz M. Tyranowski , Mathieu Desbrun

A variant of the usual Lagrangian scheme is developed which describes both the equations of motion and the variational equations of a system. The required (prolonged) Lagrangian is defined in an extended configuration space comprising both…

Mathematical Physics · Physics 2016-09-21 C. M. Arizmendi , J. Delgado , H. N. Núñez-Yépez , A. L. Salas-Brito

Employing a phase space which includes the (Riemann-Liouville) fractional derivative of curves evolving on real space, we develop a restricted variational principle for Lagrangian systems yielding the so-called restricted fractional…

Mathematical Physics · Physics 2018-03-01 Fernando Jiménez , Sina Ober-Blöbaum

We present a phenomenological Lagrangian and Poisson brackets for obtaining nondissipative hydrodynamic theory of supersolids. A Lagrangian is constructed on the basis of unification of the principles of non-equilibrium thermodynamics and…

Statistical Mechanics · Physics 2009-02-17 A. S. Peletminskii

A simple variational Lagrangian is proposed for the time development of an arbitrary density matrix, employing the "factorization" of the density. Only the "kinetic energy" appears in the Lagrangian. The formalism applies to pure and mixed…

Fluid Dynamics · Physics 2009-11-10 R. Englman , A. Yahalom

In this paper we provide a variational derivation of the Euler-Poincar\'e equations for systems subjected to external forces using an adaptation of the techniques introduced by Galley and others. Moreover, we study in detail the underlying…

Mathematical Physics · Physics 2020-08-26 David Martín de Diego , Rodrigo T. Sato Martín de Almagro

The dynamical motion of mechanical systems possesses underlying geometric structures, and preserving these structures in numerical integration improves the qualitative accuracy and reduces the long-time error of the simulation. For a single…

Numerical Analysis · Mathematics 2017-03-10 Helen Parks , Melvin Leok

It is well known that the Lagrangian and Hamiltonian descriptions of field theories are equivalent at the discrete time level when variational integrators are used. Besides the symplectic Hamiltonian structure, many physical systems exhibit…

Numerical Analysis · Mathematics 2024-01-18 Andrea Brugnoli , Volker Mehrmann

In this paper, we develop the theoretical foundations of discrete Dirac mechanics, that is, discrete mechanics of degenerate Lagrangian/Hamiltonian systems with constraints. We first construct discrete analogues of Tulczyjew's triple and…

Symplectic Geometry · Mathematics 2015-02-13 Melvin Leok , Tomoki Ohsawa

We introduce new Langevin-type equations describing the rotational and translational motion of rigid bodies interacting through conservative and non-conservative forces, and hydrodynamic coupling. In the absence of non-conservative forces…

Computational Physics · Physics 2017-12-14 Ruslan L. Davidchack , Thomas E. Ouldridge , Michael V. Tretyakov

This paper describes a fourth-order integration algorithm for the gravitational N-body problem based on discrete Lagrangian mechanics. When used with shared timesteps, the algorithm is momentum conserving and symplectic. We generalize the…

Astrophysics · Physics 2010-11-11 Will M. Farr , Edmund Bertschinger

A basic leapfrog integrator and its energy-preserving and variational / symplectic variants are proposed and studied for the numerical integration of the equations of motion of relativistic charged particles in an electromagnetic field. The…

Numerical Analysis · Mathematics 2023-04-27 Ernst Hairer , Christian Lubich , Yanyan Shi

Most physical systems are modelled by an ordinary or a partial differential equation, like the n-body problem in celestial mechanics. In some cases, for example when studying the long term behaviour of the solar system or for complex…

Probability · Mathematics 2016-08-16 Jacky Cresson , Sébastien Darses

This work proposes a suite of numerical techniques to facilitate the design of structure-preserving integrators for nonlinear dynamics. The celebrated LaBudde-Greenspan integrator and various energy-momentum schemes adopt a difference…

Numerical Analysis · Mathematics 2023-05-17 Ju Liu

Structure-preserving linearly implicit exponential integrators are constructed for Hamiltonian partial differential equations with linear constant damping. Linearly implicit integrators are derived by polarizing the polynomial terms of the…

Numerical Analysis · Mathematics 2024-03-19 Murat Uzunca , Bülent Karasözen

We investigate how the theory of self-adjoint differential equations alone can be used to provide a satisfactory solution of the inverse vatiational problem. For the discrete system, the self-adjoint form of the Newtonian equation allows…

Classical Physics · Physics 2018-05-22 Benoy Talukdar , Supriya Chatterjee , Sekh Golam Ali

One of the difficulties encountered when studying physical theories in discrete space-time is that of describing the underlying continuous symmetries (like Lorentz, or Galilei invariance). One of the ways of addressing this difficulty is to…

Exactly Solvable and Integrable Systems · Physics 2009-11-10 Vladimir Dorodnitsyn , Roman Kozlov , Pavel Winternitz

We develop a method for systematically constructing Lagrangian functions for dissipative mechanical, electrical and, mechatronic systems. We derive the equations of motion for some typical mechatronic systems using deterministic principles…

Classical Physics · Physics 2012-11-20 A. Allison , C. E. M. Pearce , D. Abbott

We analyze the relation of the notion of pluri-Lagrangian systems, which recently emerged in the theory of integrable systems, to the classical notion of variational symmetry, due to E. Noether.

Mathematical Physics · Physics 2013-07-15 Yuri B. Suris

We present the symplectic algorithm in the Lagrangian formalism for the Hamiltonian systems by virtue of the noncommutative differential calculus with respect to the discrete time and the Euler--Lagrange cohomological concepts. We also show…

Computational Physics · Physics 2007-05-23 H. Y. Guo , Y. Q. Li , K. Wu