Effects of a Dynamic Injection Flow Rate on Slug Generation in a Cross-Junction Square Microchannel

Abstract

The injection flow rates of two liquid phases play a decisive role in the slug generation of the liquid-liquid slug flow. However, most injection flow rates so far have been constant. In order to investigate the effects of dynamic injection flow rates on the slug generation, including the slug size, separation distance and slug generation cycle time, a transient numerical model of a cross-junction square microchannel is established. The Volume of Fluid method is adopted to simulate the interface between two phases, i.e., butanol and water. The model is validated by experiments at a constant injection flow rate. Three different types of dynamic injection flow rates are applied for butanol, which are triangle, rectangular and sine wave flow rates. The dynamic injection flow rate cycles, which are related to the constant slug generation cycle time t0, are investigated. Results show that when the cycle of the disperse phase flow rate is larger than t0, the slug generation changes periodically, and the period is influenced by the cycle of the disperse phase flow rate. Among the three kinds of dynamic disperse flow rate, the rectangular wave influences the slug size most significantly, while the triangle wave influences the separation distance and the slug generation time more prominently.

Numerical investigation of gas–liquid and liquid–liquidTaylor flow through a circular microchannel with a sudden expansion

“…Gupta et al [ 48 ] showed that the non‐dimensional lengths (L/D) of air‐bubble and water‐plug are 2 and 1.3, respectively. More recently, Qian et al [ 93 ] employed numerical and experimental techniques to find a range of 1.56–2.07 for slug length and 2.07–3.02 for plug length. The difference between the lengths identified compared to the results in this paper is likely due to different channel diameters, phase properties, and flow conditions.…”

A Review on the Hydrodynamics of Taylor Flow in Microchannels: Experimental and Computational Studies

“…Table 8 presents the correlations for measuring the length of liquid slugs of two-phase flow in a microchannel including the void fractions. Beyond the data provided in Table 8, two other recent studies, Han and Chen [183] and Qian et al [184], are concerned with the slug length and its formation, but the correlations of slug length were not proposed by the authors. The first study numerically simulated the droplet formation at a T-junction in a microchannel.…”

Role of Hyaluronic Acid on the Nucleation Kinetics of Calcium Oxalate Hydrates in Artificial Urine Quantified with Droplet Microfluidics

“…Just after the K-junction, the serpentine shaped passive mixers are used to ensure the mixing of two aqueous streams carrying calcium and oxalate ions. While the droplets move along the serpentine passive mixers, an asymmetric drag force forms asymmetric flow patterns on droplets; consequently, the contents of droplets are mixed in each bend. − …”