Treating Smoothness and Balance during Data Exchange in Explicit Simulator Coupling or Cosimulation

TL;DR

This paper proposes a method combining data extrapolation and balance correction in cosimulation to ensure smoothness and reduce unphysical dynamics caused by approximation errors during data exchange.

Contribution

It introduces a novel approach using switch and hat functions to improve smoothness and balance accuracy in cosimulation data exchange.

Findings

Enhanced smoothness of exchanged signals.

Reduced derivatives to prevent unphysical dynamics.

Improved balance correction during data exchange.

Abstract

Cosimulation methods allow combination of simulation tools of physical systems running in parallel to act as a single simulation environment for a big system. As data is passed across subsystem boundaries instead of solving the system as one single equation system, it is not ensured that systemwide balances are fulfilled. If the exchanged data is a flow of a conserved quantity, approximation errors can accumulate and make simulation results inaccurate. The problem of approximation errors is typically addressed with extrapolation of exchanged data. Nevertheless balance errors occur as extrapolation is approximation. This problem can be handled with balance correction methods which compensate these errors by adding corrections for the balances to the signal in next coupling time step. This work aims at combining extrapolation of exchanged data and balance correction in a way that the exchanged signal not only remains smooth, meaning the existence of continuous derivatives, but even in a way reducing the derivatives, in order to avoid unphysical dynamics caused by the coupling. To this end, suitable switch and hat functions are constructed and applied to the problem.