  This paper introduces the F3ORNITS non-iterative co-simulation algorithm in
which F3 stands for the 3 flexible aspects of the method: flexible polynomial
order representation of coupling variables, flexible time-stepper applying
variable co-simulation step size rules on subsystems allowing it and flexible
scheduler orchestrating the meeting times among the subsystems and capable of
asynchronousness when subsystems constraints requires it. The motivation of the
F3ORNITS method is to accept any kind of co-simulation model, including any
kind of subsystem, regardless on their available capabilities. Indeed, one the
major problems in industry is that the subsystems usually have constraints or
lack of advanced capabilities making it impossible to implement most of the
advanced co-simulation algorithms on them. The method makes it possible to
preserve the dynamics of the coupling constraints when necessary as well as to
avoid breaking C1 smoothness at communication times, and also to adapt the
co-simulation step size in a way that is robust both to zero-crossing variables
(contrary to classical relative error-based criteria) and to jumps. Two test
cases are presented to illustrate the robustness of the F3ORNITS method as well
as its higher accuracy than the non-iterative Jacobi coupling algorithm (the
most commonly used method in industry) for a smaller number of co-simulation
steps.
