Multiphysics co-simulation: overview

Definition

The term of multiphysics co-simulation is used for the coupling known as “external” which requires data exchanges and synchronization with another software.

Principle

The principle of a multiphysics co-simulation is presented by means of the example of an electromagnetic / thermal coupling (see the following block).

In the case of an electromagnetic / thermal coupling:

• the electromagnetic and thermal solving processes are independent
• the two systems of equations are coupled by means of certain terms :

• the temperature (resulting from the thermal solving process) is a quantity that interferes in the electromagnetic system of equations by means of the physical properties of materials: magnetic permeability, resistivity, permittivity…
• the power losses (resulting from the electromagnetic solving process) is the term corresponding to the heat source of the system of equations of thermal transfer

A multiphysics co-simulation requires:

• on the one hand an exchange of information between the items of software: “Which quantities should be exchanged, in which domain and on which exchange supports?”
• on the other hand the synchronization of the exchanges and the solving processes: “At which moment should the exchanges, the solving processes be carried out ?”

Difficulties

The difficulties of the co-simulation are related to the fact that:

• the coupled software can use different solving methods (the finite element method, the analytical method, the finite difference method...)
• the studied physical phenomena can be strongly interdependent and the operation regimes can be varied (steady state regime, transient regime with very different time constants...)

Operations

From the software point of view, two operations are possible. They are presented in the table below.