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The Interplay of Elasticity and Plasticity in Elastoviscoplastic Fluid Flows in Complex Configurations

Year: 2024
Type: dissertation
Abstract: In this thesis, we delve into a class of non-Newtonian fluids called elastoviscoplastic (EVP) fluids, such as gels, pastes, mud, and foams, which exhibit both solid-like and liquid-like, behaviors depending on the stress applied. Through a combination of numerical simulations and experimental methods, this research explores the intricate interplay between elasticity and plasticity under complex flow configurations. Firstly, we show how polymer additives can uniquely tune the extensional properties of EVP fluids without impacting their shear rheology, revealing complex dynamics such as elastic instabilities and time-dependent behavior under high extensional rates. In more complex flow configurations, particularly within wavy channels, we find that even minimal elasticity can shift the EVP fluid behavior from a steady to a time-dependent regime, significantly affecting the pressure drop and the size and shape of the unyielded regions. Additionally, we demonstrate the ability of our modified EVP fluid with enhanced elasticity to prevent the development of stagnation regions, allowing complete yielding and displacement of the material. Finally, we explore how both plasticity and elasticity can modulate the turbulence characteristics of EVP fluids, altering the classical picture predicted by Kolmogorov for Newtonian fluids and giving rise to a new scaling in energy spectra and enhanced intermittency. The insights gained from this research hold significant implications for optimizing industrial processes, including 3D printing and enhanced oil recovery, as well as for enhancing the predictability and management of natural phenomena, such as mudslides and lava flows
DOI: 10.15102/0002000724
Author: Abdelgawad, Mohamed
Language: English
Open Access status: green
OpenAlex ID: W6904814894
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