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Published on: March 5, 2014
Non-Newtonian thin films with normal stresses: dynamics and spreading
1Laboratoire de Physique Statistique de l'ENS, UMR8550 du CNRS, 24 rue Lhomond, 75231, Paris Cedex 05, France. boudaoud@lps.ens.fr
The European Physical Journal. E, Soft Matter
|March 23, 2007
Summary
Investigating non-Newtonian fluid thin films on solid substrates, this study reveals the dynamic contact angle depends logarithmically on fluid properties and contact line velocity. This offers insights into fluid dynamics and material science.
Area of Science:
- Fluid dynamics
- Rheology
- Materials science
Background:
- Thin films on solid substrates are crucial in various industrial applications.
- Understanding the behavior of non-Newtonian fluids is complex due to their non-linear rheology.
- Normal stress differences significantly influence fluid dynamics.
Purpose of the Study:
- To investigate the dynamics of thin films of non-Newtonian fluids on horizontal substrates.
- To model the motion of an advancing contact line for such fluids.
- To determine the factors influencing the apparent dynamic contact angle.
Main Methods:
- Developed two coupled evolution equations for film thickness and shear rate.
- Utilized the lubrication approximation for mathematical modeling.
- Applied the framework to analyze advancing contact line motion.
Main Results:
- The apparent dynamic contact angle exhibits a logarithmic dependence.
- This dependence is on a specific lengthscale.
- The lengthscale is determined by fluid rheology and contact line velocity.
Conclusions:
- The study provides a model for predicting dynamic contact angles in non-Newtonian thin films.
- Rheological properties and velocity are key determinants of contact angle behavior.
- Findings are relevant for applications involving non-Newtonian fluid coating and spreading.
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