Curved jets of viscous fluid : interactions with a moving wall

摘要: The processes where a jet of viscous fluid hits moving surface arise in various industrial and everyday-life applications. A simple example is pouring honey onto pancake. Similar are used the production glass wool, thermal isolation, three-dimensional polymeric mats, para-aramid fibers. In all these liquid emerges from nozzle driven by gravity possibly centrifugal Coriolis forces towards surface. performance depends strongly on properties between Very often experimental study very difficult or sometimes even impossible. Therefore, modeling can give some insight into process describe influence parameters performance. one think are: flow velocity at nozzle, velocity, distance surface, such as viscosity. One simplest examples look falling under an oriented belt. There vast amount literature jets hitting stationary but only few publications involving one. our experiments we identify three regimes: i) concave shape aligned with orientation (comparable to ballistic trajectory), ii) vertical shape, iii) convex convexity concaveness characterizes regimes. addition this overall structure, instationary boundary effects be observed near Moreover, when does not point vertically down whole instationary. To use model which takes account inertia, viscosity, gravity, disregards bending. This allows us focus large-scale while avoiding bending buckling regions ends. Also, neglect tension assume isothermal Newtonian. key issue for conditions shape. They follow conservation momentum equation hyperbolic correct consideration characteristic directions that each end. also provides criterion partitioning parameter space physical quantity regimes transfer through cross-section, has contributions both inertia due dominates everywhere jet, therefore relevant. viscosity belt, they equal should direction gravity. From follows. tangency belt becomes important. gives alternative characterization inertial, viscous-inertial, respectively. prove existence investigate uniqueness. When have non-uniqueness, up solutions possible, explains behaviour experimentally. comparison theory shows qualitative agreement. similar rotatory fiber spinning modeled using same approach. out rotating rotor cylindrical (the ‘coagulator’). contains four possible situations. Two correspond inertial viscous-inertial discussed before. two others different types non-existence jets, because no reach coagulator (causing real-world wind around rotor), match velocities coagulator. An interesting fact situation possible; would require rotate least half its angular velocity.