The role of the rheological properties of non-newtonian fluids in controlling dispersive mixing in a batch electrophoretic cell with Joule heating

Abstract

The problem of the effect of Joule heating generation on the hydrodynamic profile and the solute transport found in electrophoretic devices is addressed in this article. The research is focused on the following two problems: The first one is centered around the effect of Joule heating on the hydrodynamic velocity profile and it is referred to as "the carrier fluid problem." The other one is related to the effect of Joule heating on the solute transport inside electrophoretic cells and it is referred to as "the solute problem". The hydrodynamic aspects were studied first to yield the velocity profiles required for analysis of the solute transport problem. The velocity profile obtained in this study is analytical and the results are valid for non-Newtonian fluids carriers. To this end, the power-law model was used to study the effect of the rheology of the material in conjunction with the effect of Joule heating generation inside batch electrophoretic devices. This aspect of the research was then effectively used to study the effect of Joule heating generation on the motion of solutes (such as macromolecules) under the influence of non-Newtonian carriers. This aspect of the study was performed using an area-averaging approach that yielded analytical results for the effective diffusivity of the device

Batch electrophoretic cells with Eyring fluids: Analysis of the hydrodynamics

“…It is observed that the effect of the Joule heating promotes the increase of the velocity in both directions; this effect is smaller when the Joule heating number decreases. This behavior is in agreement with that shown by fluids that obey the power-law and CEF model in the region near the high-temperature wall [9,10].…”

“…The velocity profile computed in this investigation is useful in making comparisons among the carrier fluids with different rheologies [1,2,9,10] value of the Joule heating number is high enough to produce a temperature value at the center of the cell which is higher than the temperature values at the walls. Figure 5 shows the remarkably different behavior that non-Newtonian carrier fluids may demonstrate under the influence of the Joule heating effect, compared to the behavior of Newtonian carriers.…”

“…The objectives of the present study are (i) to increase knowledge of the behavior of non-Newtonian carrier fluids used to control convective-diffusive problems inside a discontinuous electrophoretic cell; (ii) to improve understanding of the influence of Joule heating on the behavior of the temperature profile inside the electrophoretic cell; (iii) to determine the influence of Joule heating on the hydrodynamic velocity profile inside the electrophoretic cell for the case of Eyring-model non-Newtonian carriers [1]; (iv) to compare the results of the present study with those obtained using other rheologies analyzed in previous studies [1,2,6,9]. According to the above general objectives, the device selected to perform the analysis is shown in Fig.…”

“…Less known is the use of carrier rheology and related factors to maintain low levels of mixing due to Joule heat generation, and/or to favor enhancement of separation efficiency. Modification of the carrier-fluid rheology to decrease free convection currents has also been suggested [1,9]. More recently, this aspect has been studied systematically by Bosse et al [9,10] for the case of the power-law model.…”

“…Modification of the carrier-fluid rheology to decrease free convection currents has also been suggested [1,9]. More recently, this aspect has been studied systematically by Bosse et al [9,10] for the case of the power-law model. With the same objective, fluids that follow the Eyring model have been used in the present investigation to study the potential effect of such a rheology on decreasing the impact of the Joule heat generation on free convection currents.…”