Vorticity and Symplecticity in Multi-Symplectic Lagrangian Gas Dynamics

Abstract

The Lagrangian, multi-dimensional, ideal, compressible gasdynamic equations are written in a multi-symplectic form, in which the Lagrangian fluid labels, $m^i$ (the Lagrangian mass coordinates) and time $t$ are the independent variables, and in which the Eulerian position of the fluid element $\mathbf{x}=\mathbf{x}(\mathbf{m},t)$ and the entropy $S=S(\mathbf{m},t)$ are the dependent variables. Constraints in the variational principle are incorporated by means of Lagrange multipliers. The constraints are: the entropy advection equation $S_t=0$, the Lagrangian map equation ${\mathbf{x}}_t=\mathbf{u}$ where $\mathbf{u}$ is the fluid velocity, and the mass continuity equation which has the form $J=\tau$ where $J=\det (x_{ij})$ is the Jacobian of the Lagrangian map in which $x_{ij}=\partial x^i/\partial m^j$ and $\tau =1/\rho$ is the specific volume of the gas. The internal energy per unit volume of the gas $\epsilon =\epsilon (\rho ,S)$ corresponds to a non-barotropic gas. The Lagrangian is used to define multi-momenta, and to develop de-Donder Weyl Hamiltonian equations. The de Donder Weyl equations are cast in a multi-symplectic form. The pullback conservation laws and the symplecticity conservation laws are obtained. One class of symplecticity conservation laws give rise to vorticity and potential vorticity type conservation laws, and another class of symplecticity laws are related to derivatives of the Lagrangian energy conservation law with respect to the Lagrangian mass coordinates $m^i$. We show that the vorticity-symplecticity laws can be derived by a Lie dragging method, and also by using Noether's second theorem and a fluid relabelling symmetry which is a divergence symmetry of the action. We obtain the Cartan-Poincaré form describing the equations and we discuss a set of differential forms representing the equation system.

48 pages, 0 figures

References in corpus (12)

• Momentum Maps and Classical Relativistic Fields. Part II: Canonical Analysis of Field Theories
• Multisymplectic formulation of fluid dynamics using the inverse map
• Local and Nonlocal Advected Invariants and Helicities in Magnetohydrodynamics and Gas Dynamics I: Lie Dragging Approach
• Local and Nonlocal Advected Invariants and Helicities in Magnetohydrodynamics and Gas Dynamics II: Noether's Theorems and Casimirs
• Potential Vorticity in Magnetohydrodynamics
• Clebsch Potentials in the Variational Principle for a Perfect Fluid
• Variational formulation of ideal fluid flows according to gauge principle
• Multi-Symplectic Magnetohydrodynamics: II, Addendum and Erratum
• Conserved integrals for inviscid compressible fluid flow in Riemannian manifolds
• Topological soliton in magnetohydrodynamics
• Multi-Symplectic Magnetohydrodynamics
• Multi-Symplectic Lagrangian, One-Dimensional Gas Dynamics

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• Variational Principles and Applications of Local Topological Constants of Motion for Non-Barotropic Magnetohydrodynamics