A model of the unsteady response of a backward‐facing compliant step

Abstract

SUMMARYA large number of industrial surface coating and continuous casting operations require a fluid to flow from a reservoir, over a compliant step, onto a moving substrate. The contact line between the compliant step and substrate in such cases generally responds in an unsteady manner, depending on flow conditions, which can have an important influence on the surface quality of the final product. This work describes the development of a computational fluid dynamics (CFD) model for predicting this unsteady response, with a particular emphasis on isolating the natural frequency of the contact line in a backward-facing step configuration. The compliant step was developed and implemented in the context of a pressure-based finite-element/finite-volume CFD solution, implicit in time, and considers in-surface forces based on a surface tension coefficient or an elastic membrane.

Unsteady Flow Predictions of Initial Surface Formation in Aluminum Strip Casting

“…The period of oscillation also is based on reference 15, where a frequency of 100 Hz is cited, and also is based on the estimation of the natural frequency (under isothermal conditions) of the interface movement from analytical and computational testing. [13,14] In the latter case, a frequency on the vicinity of 60 Hz is suggested. Therefore, solutions in the range of 60 to 100 Hz are presented.…”

“…[12] for a backward-facing compliant step configuration, similar to the situation here, has been undertaken for inclusion in CFD programs. [13,14] The approach considers both membrane and surface tension coefficient models for c and allows for the direct prediction of the interface shape and movement in response to adjacent fluid transport. An alternative approach is to utilize an available experimental profile in conjunction with an analytical solution (based on restricting the interface shape to a family of constant radius curves) for the interface shape and contact line position.…”

“…Other investigations attempt to determine the natural frequency of the backward-facing compliant step configuration, of which Figure 1 is an example of, under various casting conditions. [13,14] There has been some experimental work aimed at observing the affect of fluid flow, interfacial heat transfer, and meniscus/mold movement in the contact region on as-cast surface defects. Defects include the segregation of alloy (macro and micro) and tranverse surface striations (also called oscillation marks in steel processing).…”