Author(s)

M. Watanabe, G. Kudou & K. Hara

Abstract

This paper deals with a theoretical stability analysis of a flow-induced wave generated in a flexible web subjected to fluid flow in a narrow gap. The flexible web is subjected to both fluid flow and in-plane tensile force. The flow-induced wave occurs to the flexible web resulting from fluid-structure interaction between out-of-plane motion of the flexible web and the fluid flow. The effect of the fluid flow and tensile force on the stability of the wave is examined. The theoretical results show that traveling-wave type unstable wave occurs to the flexible web due to the fluid flow in the narrow gap, and clarify the dispersion relation of the flow-induced wave of the web, i.e., phase velocity (traveling-wave speed) and growth rate of the wave, which are as a function of the flow velocity and tensile force. The theoretical results are verified by experiments on the most unstable wave number and critical flow velocity. Keywords: flow-induced wave, flexible web, dispersion relation, fluid-structure interaction. 1 Introduction In the manufacturing process of flexible materials, such as a paper, sheet and plastic films, the flexible materials are subjected to a fluid flow in a narrow gap for non-contact support and drying. However the interaction of the thin film with the fluid flow causes an unstable wave. The flow-induced wave reduces the process efficiency and generates noise, in some case, causes fatigue failure to the thin film.

Keywords

flow-induced wave, flexible web, dispersion relation, fluid-structure interaction