Isolated Taylor Bubbles in Co-Current with Shear Thinning CMC Solutions in Microchannels-A Numerical Study

• Type: Article in International Scientific Journal
• Date: 2020

Authors

Moreira, AI (Author) Other; Rocha, LAM (Author) Other; Carneiro, J (Author) Other; Araujo, JDP (Author) FEUP; Campos, JBLM (Author) FEUP; Miranda, JM (Author) FEUP

Journal

The Journal is awaiting validation by the Administrative Services.

Title: PROCESSES

Vol. 8

Final page: 242

ISSN: 2227-9717

Indexing

ISI Web of Knowledge - 1 Citation

Scopus - 2 Citations

Other information

Authenticus ID: P-00R-T2J

DOI: 10.3390/pr8020242

Abstract (EN): Slug flow is a multiphase flow pattern characterized by the occurrence of long gas bubbles (Taylor bubbles) separated by liquid slugs. This multiphase flow regime is present in many and diversified natural and industrial processes, at macro and microscales, such as in eruption of volcanic magmas, oil recovery from pre-salt regions, micro heat exchangers, and small-sized refrigerating systems. Previous studies in the literature have been mostly focused on tubular gas bubbles flowing in Newtonian liquids. In this work, results from several numerical simulations of tubular gas bubbles flowing in a shear thinning liquid in microchannels are reported. To simulate the shear thinning behavior, carboxymethylcellulose (CMC) solutions with different concentrations were considered. The results are compared with data from bubbles flowing in Newtonian liquids in identical geometric and dynamic conditions. The numerical work was carried out in computational fluid dynamics (CFD) package Ansys Fluent (release 16.2.0) employing the volume of fluid (VOF) methodology to track the volume fraction of each phase and the continuum surface force (CSF) model to insert the surface tension effects. The flow patterns, the viscosity distribution in the liquid, the liquid film thickness between the bubble and the wall, and the bubbles shape are analyzed for a wide range of shear rates. In general, the flow patterns are similar to those in Newtonian liquids, but in the film, where a high viscosity region is observed, the thickness is smaller. Bubble velocities are smaller for the non-Newtonian cases.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 13