### Project A1

**Principal Investigator:**

*Stefanie Braun, Applied and Computational Mathematics, RWTH Aachen
University*

**Main Collaborators in the Research Unit:**

*Jürgen Dreher, Theoretical Physics I, Ruhr-University Bochum*

*Rainer Grauer, Theoretical Physics I, Ruhr-University Bochum*

## Consistent Coupling of Electromagnetics to Thermodynamics for Batteries

Batteries and other polarisable media contain moving charge carriers that are subject to electromagnetic forces exerted by the electrodes and the other particles. In order to model the resulting particle motion self-consistently, the thermodynamic conservation equations for mass, momentum and energy are combined with the Maxwell equations describing the evolution of electromagnetic fields. The question how to correctly couple these two different fields of physics has not been answered satisfactorily yet.

This project focuses on the derivation of a consistent macroscopic theory for the moving charges. To avoid contradictions, the coupling of the two subsystems will already be realized on the microscopic particle scale, ensuring that each particle's total momentum and energy, including electromagnetic contributions, are conserved. The resulting equations are then coarse-grained to obtain the macroscopic description. An entropy principle will be applied to find a closure for the system.

(A) Modeling of Coupled Systems
Plasma Interactions