Lattice-Boltzmann Simulation and Experimental Validation of a Microfluidic T-Junction for Slug Flow Generation
Department of Mechanical Engineering, Cooperative State University Mannheim, Coblitzallee 1-9, 68163 Mannheim, Germany
Institute of Chemical Process Engineering, Mannheim University of Applied Sciences, Paul-Wittsack-Str. 10, 68163 Mannheim, Germany
Author to whom correspondence should be addressed.
ChemEngineering 2019, 3(2), 48; https://doi.org/10.3390/chemengineering3020048
Received: 24 January 2019 / Revised: 4 April 2019 / Accepted: 23 April 2019 / Published: 5 May 2019
(This article belongs to the Special Issue Advances, Intensification, and Emerging Technologies in Fluid Flow and Transfer Processes)
We investigate the interaction of two immiscible fluids in a head-on device geometry, where both fluids are streaming opposite to each other. The simulations are based on the two-dimensional (2D) lattice Boltzmann method (LBM) using the Rothman and Keller (RK) model. We validate the LBM code with several benchmarks such as the bubble test, static contact angle, and layered flow. For the first time, we simulate a head-on device by forcing periodicity and a volume force to induce the flow. From low to high flow rates, three main flow patterns are observed in the head-on device, which are dripping-squeezing, jetting-shearing, and threading. In the squeezing regime, the flow is steady and the droplets are equal. The jetting-shearing flow is not as stable as dripping-squeezing. Moreover, the formation of droplets is shifted downstream into the main channel. The last flow form is threading, in which the immiscible fluids flow parallel downstream to the outlet. In contrast to other studies, we select larger microfluidic channels with 1-mm channel width to achieve relatively high volumetric fluxes as used in chemical synthesis reactors. Consequently, the capillary number of the flow regimes is smaller than 10−5. In conclusion, the simulation compares well to experimental data.