Dual PIC: a structure preserving method for discretizing Lie-Poisson brackets

TL;DR

The paper introduces Dual PIC, a novel discretization method for Lie-Poisson Hamiltonian systems that preserves structure by using two discrete representations constrained to match via Casimir invariants, demonstrated on fluid and plasma models.

Contribution

It proposes a new dual representation discretization strategy for Lie-Poisson systems that maintains geometric structure and invariants during simulations.

Findings

Successfully applied to 2D vorticity equations

Effectively discretized Vlasov-Poisson system

Preserves Casimir invariants throughout simulations

Abstract

We consider a general discretization strategy for Hamiltonian field theories generated by Lie-Poisson brackets which we call dual PIC (DPIC). This method involves prescribing two different discrete representations of the dynamical variable which are constrained as a Casimir invariant of the flow to coincide with one another via an L2 projection throughout the entire simulation. This allows one to leverage the relative advantages of each discrete representation. We begin by describing DPIC as applied to a general Lie-Poisson system and then provide illustrative examples: the discretization of the two-dimensional vorticity equations and the Vlasov-Poisson equation.