“…In this paper, inspired by the methodology of data assimilation, especially variational data assimilation in continuous time (for relevant works we refer e.g. to [13,19,26,29,30,44,46,52]), we seek to minimise the misfit functional (u, p, y) → (1 − λ) Q(•, •, u, ∇u, p) − q + λ y over all admissible triplets (u, p, y) which satisfy (1.1), for a fixed weight λ ∈ (0, 1). The role of this weight is to obtain essentially a Pareto family of extremals, one for each value λ, even though in this paper we do not pursue further this viewpoint of vector-valued minimisation (the interested reader may e.g.…”