Removing the warm up period from the output of a time-dependent simulation

A simulation software often computes a configuration in a step response fashion. Indeed, it starts from an approximate initial state and iteratively advances towards a statistically converged state that satisfies the physical constraints of the model. In Computational Fluid Dynamics (CFD), for instance, the conservation laws are progressively enforced, resulting in global signals with similar characteristics. Consequently, before reaching a statistically steady state, there is a warm-up period unsatisfactory from the modeling point of view, that should be discarded in our data collection.