The Thermodynamics and Transport Phenomena Laboratory (T²PL) of the Department of Chemical Engineering at the Cyprus University of Technology’s, is looking for three highly enthusiastic and strongly motivated PhD candidates to join the group, starting September 2020.
Qualifications: Successful candidates must possess a Bachelor’s degree and should possess a postgraduate degree (Μaster’s level) from an accredited University in Chemical Engineering, or Theoretical/Computational Chemistry, Computational Materials Science, or Applied Computational Physics. Previous experience in the below-mentioned research topics will be considered as a strong advantage.
Project 1: Understanding fluids with an anisotropic stress tensor
It has been almost exclusively assumed that the stress tensor employed in Fluid mechanics is symmetric, which implies there is no rotational interaction among particles or molecules. Almost all kinetic-type theories for both simple fluids (such as water) and complex fluids (such as polymeric melts, blood, particle suspensions, and other micro-structured fluids) give a symmetric stress tensor; even in cases where an asymmetric contribution is derived it is negligibly small. Such a consideration assumes that matter is continuously distributed throughout the body. However, the micro-rotation of freely suspended particles in fluid suspensions gives rise to an antisymmetric stress, known as couple stress, more likely to arise in fluids with very large molecules. A comprehensive theory, named Couple stress theory (CST) in this regard is the one developed by Stokes which is found to be quite useful in the description of various types of lubricants, blood, and polymeric suspensions. In the present doctoral work, we aim to derive the constitutive model via the use of either the Generalized Bracket or GENERIC formalisms of non-equilibrium thermodynamics (NET). The attractive advantage of employing a NET formalism is that the resulting constitutive model is, by construction, consistent with the laws of thermodynamics. Thus, by using NET we will assert as to whether the asymmetric stress tensor proposed in CST is not in violation of the laws of NET, e.g. the second law of thermodynamics which necessitates a non-negative rate-of-entropy production.
Project 2: Understanding the dynamical behavior of chains absorbed on nanoparticles under an externally applied flow field.
Polymer nanocomposites (PNCs), i.e., systems composed of particles of the nanoscale size of any shape (spheres, rods, or sheets) dispersed within a polymer matrix have received cumulative attention in the last decade due to their alluring and unique properties, that render them ideal candidates for several applications. In many cases, e.g. when hydrogen bonds emerge, the polymer chains absorb on the surface of the nanoparticles. In the present doctoral work, to derive the constitutive model via the use of either the Generalized Bracket or GENERIC formalisms of non-equilibrium thermodynamics (NET). The attractive advantage of employing a NET formalism is that the resulting constitutive model is, by construction, consistent with the laws of thermodynamics. The constitutive model to be proposed will provide predictions for the fraction of absorbed chains as a function of the strength of the imposed flow, as well and as their rheological properties (e.g. their viscosity).
Project 3: Rheological modeling of thixotropic fluids.
Many materials of industrial interest, such as emulsions, colloids, suspensions, and foams, exhibit a yield stress, i.e., they flow only above this critical stress and behave as elastic solids otherwise. Such materials are encountered in many sectors, such as in the oil industry (e.g., crude oil and drilling fluids), the construction sector (e.g., cement pastes and fresh concrete), the food industry (e.g., ketchup, margarine, and mayonnaise), and the pharmaceutics/cosmetics industry (e.g., blood, pastes, and foams). Recently, we proposed a rheological model which also predicts, in addition to a yield shear stress, a yield normal stress difference, which were never before been reported in the literature. More recently, Thomson et al. measured a yield stress tensor via rheological measurements for various thixotropic fluids, such as hair gels, and pastes. In the present doctoral work, the candidate should derive a refined constitutive model via the use of either the Generalized Bracket or GENERIC formalisms of non-equilibrium thermodynamics (NET). The attractive advantage of employing a NET formalism is that the resulting constitutive model is, by construction, consistent with the laws of thermodynamics. The constitutive model to be proposed will provide predictions for the rheological properties of these fluids (e.g. their viscosity), which will be compared against available experimental data.
The last date to apply for postgraduate studies is Monday, 11 May 2020
For more information candidates could contact Assistant Professor, Dr Pavlos S. Stephanou at firstname.lastname@example.org
For applications, click here