“…where A = 10 −2 , andh N = 0.54 is the initial value of the thickness that gives, for a pure streamwise saturated structure, the same local flow rate in the streamwise direction as a flat film of thickness h = 1 ( § 5.3 in Lerisson et al 2020). We introduce the moving reference frame at the linear advection velocity u (ξ = x − ut, y).…”