Electrokinetic-Hydrodynamics (EKHD): An Efficient Framework for Systematic Research

Jennifer Anne Pascal1, Mario Oyanader2, and Pedro E. Arce2. (1) Chemical Engineering, Tennessee Tech University, PH-214, Cookeville, TN 38505, (2) Chemical Engineering, Tennessee Technological University, Department of Chemical Engineering, P.O. Box 5013, Cookeville, TN 38505

Currently there are many problems in Chemical Engineering that involve the application of an applied electrical field to a fibrous or porous media in a variety of relevant technological processes. Examples of these types of problems are the separation of biomacromolecules, such as proteins and DNA, bioremediation, drug delivery, and coating flows, among others. These types of problems can be described by the fundamentals of “electrokinetic-hydrodynamics” or EKHD, for short ([1]). What makes the applications within the domain of electrokinetic-hydrodynamics unique is that unlike electrochemical systems, bulk motion of the fluid occurs. Therefore, we can view EKHD as involving two domains: the motion of the fluid (electrohydrodynamics) and the motion of the solute/analyte (electro and convective-diffusive transport). It is apparent that these two domains are representative of two different scales, the continuum (fluid) and the discrete (solute) . This contribution will discuss how EKHD is an efficient framework for the investigation of systems with low and high values of applied electrical fields.

For the understanding the behavior of the systems in EKHD, one must have a basic background in fluid mechanics, and mass, momentum, and energy conservation. These concepts can then be used to link the principles of electrokinetics to those of hydrodynamics to model the fluid motion, i.e. “electrohydrodynamics”. Once this knowledge is acquired, then the solute/analyte problem can be described. The coupling between these two domains (i.e. fluid and solute) can be effectively handled by using the spatial averaging technique ([2]). This powerful up-scaling approach allows for the computation of analytical expressions which lead to effective, or alternative “macro,” coefficients (i.e. effective velocity and diffusivity) that represent the macroscopic behavior of the system. These coefficients can then be used to determine information relevant to practical applications such as the optimal time of separation of biomacromolecules, time for the cleaning protocol in soil remediation, among others. In this contribution, the authors will discuss the method of EKHD and the different elements associated with it; for the didactic aspects, typical assignments/exercises associated with this field of research including, problems and projects, will be included.