Long wave theory for experimental devices with compressed/expanded surfactant monolayers

Higuera, María and Perales Perales, José Manuel and Vega de Prada, José Manuel (2013). Long wave theory for experimental devices with compressed/expanded surfactant monolayers. In: "The Fifth International Symposium "Instabilities and Bifurcations in Fluid Mechanics" 2013. (BIFD2013)", 08/07/2013 - 11/07/2013, Haifa, Israel.. pp. 4140401-4140413.

Description

Title: Long wave theory for experimental devices with compressed/expanded surfactant monolayers
Author/s:
  • Higuera, María
  • Perales Perales, José Manuel
  • Vega de Prada, José Manuel
Item Type: Presentation at Congress or Conference (Article)
Event Title: The Fifth International Symposium "Instabilities and Bifurcations in Fluid Mechanics" 2013. (BIFD2013)
Event Dates: 08/07/2013 - 11/07/2013
Event Location: Haifa, Israel.
Title of Book: Special issue: Bifurcations in fluid dynamics. Selected papers from the BIFD2013 Conference
Date: July 2013
Subjects:
Faculty: E.T.S.I. Aeronáuticos (UPM)
Department: Fundamentos Matemáticos de la Tecnología Aeronáutica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

Surfactant monolayers are of interest in a variety of phenomena, including thin film dynamics and the formation and dynamics of foams. Measurement of surface properties has received a continuous attention and requires good theoretical models to extract the relevant physico- chemical information from experimental data. A common experimental set up consists in a shallow liquid layer whose free surface is slowly com- pressed/expanded in periodic fashion by moving two slightly immersed solid barriers, which varies the free surface area and thus the surfactant concentration. The simplest theory ignores the fluid dynamics in the bulk fluid, assuming spatially uniform surfactant concentration, which requires quite small forcing frequencies and provides reversible dynamics in the compression/expansion cycles. Sometimes, it is not clear whether depar- ture from reversibility is due to non-equilibrium effects or to the ignored fluid dynamics. Here we present a long wave theory that takes the fluid dynamics and the symmetries of the problem into account. In particular, the validity of the spatially-uniform-surfactant-concentration assumption is established and a nonlinear diffusion equation is derived. This allows for calculating spatially nonuniform monolayer dynamics and uncovering the physical mechanisms involved in the surfactant behavior. Also, this analysis can be considered a good means for extracting more relevant information from each experimental run.

More information

Item ID: 29965
DC Identifier: http://oa.upm.es/29965/
OAI Identifier: oai:oa.upm.es:29965
Deposited by: Memoria Investigacion
Deposited on: 29 Apr 2015 12:51
Last Modified: 17 Jan 2017 12:13
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