Measuring the impact of channel length on liquid flow through an ideal Plateau border and node system

Abstract

The following work highlights the impact of Plateau border (PB) length, l1, on the apparent surface viscosity, μs, of a flow rate controlled PB and node system using a novel experimental setup.

Surface rheological measurements of isolated food foam systems

“…24 The contrast between low and high surface viscosities is thought to be responsible for the two macroscopic regimes of the node-dominated and channel-dominated foam drainage, respectively, which describes whether the bulk of flow dissipation is thought to occur at the nodes or within the PBs themselves. 6,19,25 The extremely low values of surface viscosity found by Zell et al 22 and Clarke et al 6 for soluble LMWS systems therefore suggest that flow dissipation occurs primarily in the nodes in these cases, with surface viscosity having little impact on macroscopic foam drainage.…”

“…Different surfactants dramatically alter the physical properties of the interface, whose surface rheology and the subsequent impact on liquid flow are still extensively studied in both liquid films and foam channels alike. [5][6][7][8][9][10][11][12] Physics of Fluids ARTICLE scitation.org/journal/phf Theoretical modeling of foam channels has presented a significant challenge to researchers. 13 The already complex geometries within the foam microstructure undergo expansion and distortion, with these phenomena determined, to an extent, by the rheology of the bulk liquid and the gas-liquid interface, which themselves are dependent on the liquid flow rate.…”

“…By creating spatially "ideal" arrangements of foam channels within bespoke frames, researchers have been able to probe specific physical and chemical variables that were thought to influence the nature of the interface. 15,6,7,[17][18][19][20][21] Such in situ measurements of channel surface rheology are critical, as they provide unparalleled control and measurement consistency.…”

“…So far, the study of these isolated systems has been limited to simple LMWS systems such as Tetradecyltrimethylammonium Bromide (TTAB) [19][20][21] and Sodium Dodecyl Sulphate (SDS) 6,19,20 with variations in interfacial rheology introduced by small additions of dodecanol (DOH), and bulk rheology by the addition of glycerol. Most recently, the work by Clarke et al 6 using an isolated PBnode system with a pure SDS solution has yielded surprising findings regarding previously unobserved changes in fundamental liquid channel geometries during the forced liquid flow. In addition, these results appear to confirm what are purported as the most accurate surface viscosity measurements of SDS to date, 22 predicting the airliquid interface of SDS and other soluble LMWS systems to be so low as to be considered virtually inviscid.…”

“…As the theory used by Clarke et al 6 was unable to describe the full extent of the unusual PB geometries identified, and based only on results from SDS solutions, the present study aims to further probe this promising measurement technique. In order to do this, the current work assesses a range of surfactant solutions that are anticipated to display a wide range of surface viscosities.…”