Geometrical patterns of sliding flow formed by collision of viscoelastic fluid jet on a tilted plate

Abstract

Regular geometrical patterns are formed on a sliding flow on a tilted plate when a viscoelastic fluid jet falls down from a nozzle exit to the plate by gravity. A part of the jet near the collision point to the tilted plate is oscillated to the flow direction and/or the horizontal direction by stacking on the plate at a suitable condition and it makes the regular patterns. Several regular, quasi-regular and random patterns are formed on the plate by adjusting the title angle of the plate and the height of the nozzle exit from the collision point at the plate. The pattern maps that are a chart to show the distribution of each pattern according to the nozzle height and the title angle of the plate were drawn and it makes clear that the regular patterns appear the range of the tilt angle from 30 to 60 degrees. The sliding flow velocity on the plate is an important factor for the pattern formation and is also affected by the flow rate, the nozzle diameter and the viscoelastic properties of the fluid. The sliding flow velocity and the period of the pattern are measured for the in-line stacking type and the horizontal stacking type as a representative regular pattern. The border of the in-line stacking type and horizontal stacking type coincides with the critical height for the deformation transmission property on the viscoelastic fluid jet driven by gravity, as reported by Tomita and Takahashi (Transactions of the Japan Society of Mechanical Engineers, Series B, Vol.56, No.529, 1990). The oscillation period of these regular patterns normalized by relaxation time was evaluated by the dimensional analysis method and an empirical formula to describe the oscillation period of the patterns was presented.