Transient free‐surface flows: Fluid advancing through a bed of cylinders

Abstract

The flow of a viscous liquid into a bed filled with a regular array of cylinders was observed experimentally and simulated numerically. Viscous forces were always dominant, as is expected to be the case in many actual resin transfer molding operations.Excellent agreement on the shape of the free surface was found between experiment and simulation over the full experimental range. The work accordingly validates a very simple algorithm for representing the surface motion of a fluid at its contact line with a solid surface, and extends its use to surfaces with smaller radii of curvature than considered previously. Consequently, this algorithm is expected to be valid for fluid flow into any irregularly shaped empty domain and to be useful in molding operations in inferring the presence of voiding, and of molecular orientations and conformations adjacent to fibers or other solids. IntroductionWe wish to describe in detail the motion of a liquid as it advances, with a free interface, through a loose array of cylinders placed perpendicularly to the advancing mass of liquid, as shown in Figures 1 and 2. In Figure 1 the flat liquid surface is shown advancing upward toward the array of cylinders but it has not yet reached or penetrated the array, and consequently the fluid interface is flat. Some time later, as seen in Figure 2 for one small portion of the overall flow domain, the liquid has advanced into the region between the cylinders and the advancing free liquid surface or flow front has adopted a smooth but complex geometry. It is this geometry that we wish to compute and to measure. Our motivation is as follows.High-strength composites may be manufactured by placing a mat of long fibers into a mold, typically filling 20-50% of the mold volume, and then injecting a resin at the maxiinum possible flow rate to fill the remaining void space. The properties of the cooled and solidified composite structure resulting from such a resin transfer molding (RTM) process may be affected by the details of the flow front, including those areas initially bypassed, and by the orientation and conformation of the polymer molecules at their interfaces with the fibers. Consequently we wish to model the flow process in sufficient detail to be able

Nonisothermal parison inflation in blow molding

“…Once the outer surface makes contact, it is not allowed to detach from the wall; however, the inner surface is free to deform further during the impingement process. Application of no-slip at the dynamic contact line between meniscus and solid surfaces is appropriate when viscous forces dominate surface tension effects (Kistler and Scriven, 1983;Behrens et al, 1987Behrens et al, , 1988. This is the case in blow molding operations.…”