Gas holdup and bubble size are important parameters for simulation and designing in bubble column reactors. Because based on these parameters, the available gas-liquid interfacial area is defined for mass transfer. In this paper, the results of applying magnetic fields on the velocity field and volume fraction of gas holdup are reported. Hydrodynamics of the bubble column in the reactors is inv...

Measuring the volume of a bubble, especially at its detachment, is a basic subject in gas-liquid two-phase flow research. A new indirect method for this measurement under constant flow conditions is presented. An electronic device is designed and constructed based on laser beam intensity. This device calculates the frequency of the bubble formation by measuring the total time of the formation p...

A Lagrangian-Eulerian numerical scheme for the investigation of bubble motion in turbulent flow is developed. The flow is analyzed in the Eulerian reference frame while the bubble motion is simulated in the Lagrangian one. Finite volume scheme is used, and SIMPLEC algorithm is utilized for the pressure and velocity linkage. The Reynolds stresses are modeled by the RSTM model of Launder. Upwind ...

This paper presents a 3D numerical study of the bubble generation process in a T-junction, performed with the commercial Computational Fluid Dynamics solver ANSYS Fluent v15.0.7. Numerical results on bubble generation frequency, bubble velocity, volume void fraction, bubble volume, and characteristics bubble lengths are compared with experimental data. Additionally, a new simple tting for the b...

Fast reduction of blood water volume due to ultra-filtration via hemodialysis machine and critical threshold of blood water volume can result in clinical complications such as hypotension. When blood water volume reduces during hemodialysis process, the concentration of blood forming elements will increase. One of the methods for the monitoring of the concentration changes is ultrasonic speed m...

in this paper, direct numerical simulation of two-phase incompressible gas-liquid flow for simulation of bubble motion in a microtube is presented. microtube radius is 10 µm. the interface is tracked using volume of fluid (vof) method with continuous surface force (csf) model. the flow is solved using a finite volume scheme, based on piso algorithm. numerical simulation is performed on a axisym...

The number of computational cells assigned to a small bubble is liable to be small in a volume tracking simulation of a poly-dispersed bubbly flow. The volume tracking method is, therefore, expected to at least give qualitatively reasonable predictions of bubble motion without assigning many cells. In this study, bubble motions in stagnant water and shear flows are simulated with low spatial re...

An improved numerical algorithm for front tracking method is developed to simulate the rising of a bubble in quiescent viscous liquid due to buoyancy. In the new numerical algorithm, volume correction is introduced to conserve the bubble volume while tracking the bubble’s rising and deforming, and volume flux conservation based SIMPLE algorithm is adopted to solve the Navier–Stokes equation for...

We study the effect on bubble motion of the sudden streamwise expansion of a liquid-filled tube of square cross-section, which is formed by a pair of backward-facing and forward-facing steps. When a bubble of finite volume traveling under constant volume flux reaches the backward-facing step that marks the start of the expansion, the extent to which it broadens to partially fill the expansion d...

Numerical simulation of bubble growth during pool boiling under the influence of low frequency vibration was performed to understand the influence of common vibrations such as those induced by wind, highway transportation, and nearby mechanical devices on the performance of thermal systems that rely on boiling. The simulations were done for saturated R123 boiling at 277.6 K with a 15 K wall sup...