The motion of small droplets through microfluidic channels, membrane pores, and other confined geometries presents considerable computational challenge due to drop deformation, small clearances, and complex geometries. This paper addresses the challenge by developing a moving-frame boundary-integral method and demonstrating its utility with simulations of a three-dimensional, freely-suspended deformable

The effect of the surface viscoelasticity on the drainage of the film between two gently colliding fluid particles is studied. The interfaces bounding the thin film are treated as deformable ones, which follow the surface analogous of the Upper Convected Maxwell model. The presence of the elastic forces on the interface is found to delay the viscous response of the interface, i.e., the interface behaves

In this paper, three working fluids of deionized water, anhydrous ethanol and FC-72 were used to study the transient variation of liquid film thickness on the bubble's periphery for the flow boiling in micro-channels. The experiments showed that the liquid film declined rapidly under the coupled action of evaporation and shear force of vapor flow until it was dried out. A transition point existed on

Present study concerns the solute dispersion analysis in a two-fluid model of blood flow through tubes with a thin porous layer near the absorbing wall. A thin porous layer near the wall represents an endothelial glycocalyx layer the composition of which may be attributed to the accumulation of carbohydrates, absorbed plasma proteins and macromolecules in a layer at the wall that affects the plasma

The depressurization of the surrounding chamber or superheating of the injected liquid is responsible for the flashing of the sprays, which promotes micro-explosion of many bubbles near free-surface and thereby leading to primary atomization of sprays. In this work, we propose a mathematical model, and the Dirichlet hyperboloids are used to explain the micro-explosion process while the external flashing

To realize efficient computational fluid dynamics (CFD) prediction of two-phase flow, a multi-scale framework was proposed in this paper by applying a physics-guided data-driven approach. Instrumental to this framework, Feature Similarity Measurement (FSM) technique was developed for error estimation in two-phase flow simulation using coarse-mesh CFD, to achieve a comparable accuracy as fine-mesh simulations

The process of bubble formation from submerged orifices is encountered in various industrial applications. It is therefore essential to understand the dynamics of bubble formation under such conditions. In the present work, the process of bubble formation in a steel-argon system is studied using the Local Front Reconstruction Method (LFRM), a Front Tracking method that enables the simulation of interface

The nonlinear dynamics of a spherical bubble in the confined externally driven liquid cell is considered. It is shown that volume confinement strongly affects the manifestation of the classical cavitation Blake threshold. At relatively large liquid cell exposed to a tension exceeding cavitation Blake threshold, the cavitation bubble abruptly expands to a finite radius in contrast with explosive infinite

We study both theoretically and experimentally the whipping instability in axisymmetric gaseous flow focusing realized in a converging-diverging nozzle. The lateral oscillation of both the tapering meniscus and emitted jet is explained in terms of the global linear instability of the lateral mode with the azimuthal number m=1. A comparison with previous experiments shows good agreement. The distance

When dealing with numerical simulations of boiling phenomena, the spontaneous appearance of vapor bubbles is one of the most critical feature to be addressed. Capturing bubble formation during the dynamics, instead of patching vapor regions as initial conditions, is crucial for the correct evaluation of nucleation rates and nucleation site density, two of the most important parameters characterizing

The objective of the paper is to investigate the physics involved in the compressible cavitating flows, with emphasis on the compressibility effects. 3-D numerical simulations were conducted on the open source software platform OpenFOAM, using both the native incompressible cavitation solver interPhaseChangeFOAM and implemented compressible cavitation solver, where the cavitation model and turbulence

In this study, the solid volume fraction fluctuations of different solid particles in a fluidized bed were measured using an Electrical Impedance Tomography system, which provides local fluctuation values. A wide range of particle Stokes numbers (122 ≤ Stt ≤ 3809) was tested by selecting specific particle sizes and densities. The results were compared with previous experimental studies. Since previous

The injection and atomization of gasoline fuels are critical to the performance of gasoline direct injection engines. Due to the complex nature of the primary breakup of the liquid jet in the near field, high-level details are often difficult to measure in experiments. In the present study, detailed numerical simulations are performed to investigate the primary breakup of a gasoline surrogate jet under

Natural gas pipelines that connect subsea fields to shore terminals are composed of horizontal and inclined sections. The smooth transportation of the gas is challenged by the transient flow phenomena associated with the liquid accumulation problem and its displacement along such pipelines. The current study is focused on the estimation of the critical gas flow rate required for avoiding liquid accumulation

An approximation approach for the implementation of the phase change model based on the volume-of-fluid method is proposed. In each interfacial cell, the interface normal direction is approximated to be parallel to one Cartesian axis line. The interface position is determined by the volume fraction value of the interfacial cell. The mass flux and heat flux at the interface are calculated in terms of

Flow pattern of cohesive particles in gas-solid fluidized bed is complex, and particles in different regions exhibit various flow patterns. Characterization methods in literatures are deficient in detecting local motions of particles. In this work, particle motions distribution along the axial direction was investigated by acoustic emission detection and pressure fluctuation. The axial distribution

The one-dimensional implementation of the Delayed Equilibrium Model (DEM) is known as a relatively simple yet accurate approach for prediction of critical mass flow rate, pressure and void fraction distributions for two-phase water transonic flows in ducts of variable geometry. The direct application of DEM equipped with original saturation index evolution law and Lockhart-Martinelli approach (the

Numerical simulations are conducted for the gravity–driven settling of two particles in a viscous quiescent fluid. A method is proposed to determine the scaling law of inter–particle contact time. The method is simple and general. The resulting scaling law explains the observations of literature and predicts the influences of particle–fluid density ratio, fluid viscosity, friction, rolling friction

We present the results of a systematic analysis of the morphology of the thin lubrication film surrounding a long gas bubble transported by a liquid flow in a square capillary. Direct numerical simulations of the flow are performed using the Volume-Of-Fluid method implemented in OpenFOAM, for a range of capillary and Reynolds numbers Ca=0.002−0.5 and Re=1−2000, and very long bubbles, up to 20 times

We present a combined experimental-numerical study of the primary breakup of a single-phase attenuating liquid sheet emerging from a flat fan nozzle. An experimental setup has been built to produce flat fan liquid sheets/sprays at near industrial conditions, i.e. high pressure and turbulent. The process of sheet disintegration, for a transitional and a turbulent sheet, is visualized using high-speed

We consider the linear stability of evaporating thin films falling down an inclined plate. The one sided-model presented first by “Burelbach, J.P., Bankoff, S.G., Davis, S.H., 1988, Nonlinear stability of evaporating/condensing liquid films, Journal of Fluid Mechanics 195, 463–494. ” was implemented to decouple the dynamics of the liquid than those of the vapor at the interface, at which the evaporation

Shell-and-plate heat exchangers have wide industrial applications for its excellent thermal performance with compact size, extensive temperature/pressure ratings and two-phase fluid flexibility. An in-depth study on the two-phase thermo-hydraulic behavior in the plate core is of utmost importance for its performance improvement. In this study, the flow patterns and pressure drop are experimentally

The lift force acting on an ellipsoidal bubble is known to change its sign, depending on the bubble aspect ratio. The lift reversal has often been modeled in terms of the Eötvös number defined by using the bubble major axis to account for the deformation effect on the negative lift component. This paper presents a physically reliable scaling accounting for the two mechanisms in competition related

To investigate the complex cavity evolution, hydrodynamic action and motion response of a stone impacting on the water, a calculation model is established with six degrees of freedom. The Large Eddy Simulation (LES) model is used to solve the turbulence based on Computational Fluid Mechanics (CFD). The accuracy of the numerical model is verified by comparing the numerical results with experimental

The vaporization rate of aluminum droplets in shocked flows plays a crucial role in determining the energy release rate during the combustion of the aluminized energetic materials. In this paper, the physics of the vaporization of aluminum droplets in shocked flows is numerically investigated. Surrogate models for the temporally averaged Sherwood number and Nusselt number, cast as functions of shock

Molecular dynamics simulations were carried out to investigate the static and dynamic wetting behaviors of water droplets on surfaces with single and dual structures at the nanoscale. The effects of the surface characteristic energy, pillar height, and applied force on the dynamic wetting behavior were considered in this study. The dual structures were constructed by attaching small minor bump textures

In vertical gas-liquid two-phase annular flow, the radial evolution of droplets in the gas core plays a key role in affecting the characteristic of gas carrying liquids. In this paper, the droplets size and velocity at 11 radial positions were measured with the phase Doppler anemometry and then analyzed based on the recognition method of droplet role to figure out the radial evolution characteristics

Air-water free-surface flows are extremely complicated to model physically and numerically. The development of the air-water velocity metrology has been relatively slow and is still on-going. Phase-detection needle probes have been successfully used for both laboratory and field measurements in high-turbulence air-water flows, but the signal processing is not trivial. Recently a different method, called

We report on an experimental investigation of adiabatic bubbly two-phase flow development in a DN50 pipe with a ring-shaped and a baffle-shaped constriction at different superficial velocities of gas (up to jg = 0.1400 m·s−1) and liquid (up to jl = 1.6110 m·s-1) using ultrafast electron beam X-ray computed tomography (UFXCT). From UFXCT images, cross-sectional gas holdup distributions were obtained

The present work analyses the effect of the eccentricity of diesel nozzle orifices over the spray behaviour by means of CFD simulations. Several orifice geometries with varying horizontal eccentricity (from 0.50 to 0.94) are selected. Their performance is assessed at a high injection pressure of 200 MPa, a 3 MPa back-pressure and non-evaporative conditions. The nozzle flow characteristics, including

Air-entrainment is a negative phenomenon in pump stations. The process and the underlying mechanism are far from being fully understood. Based on the previous research, the present paper numerically studies the air-entrained vortex formation in a benchmark pump sump. The bifurcation model (BM) for capturing the rotating characteristics of the vortex and the simple coupled level set and volume of fluid

The analytical solution of the Stokes-Darcy equations is derived for a Newtonian, statistically homogenous, suspension with non-Brownian (non-colloidal) rigid spherical particles. Navier-type linear slip over the surface of the particles is applied. The mathematical model is based on Brinkman's (1949) original idea for the viscous force exerted by a flowing fluid on a dense swarm of spherical particles

Spray impingement is widely applied in many fields, and the liquid film formed on the impact surface is closely related to the heat and mass transfer. In present paper, an experimental setup of the spray impingement with an air-atomizing nozzle was established to study the water film formed on a flat surface. And the planar laser-induced fluorescence technology was applied to measure the film thickness

With the rapid deployment of large oil tank, a quick and efficient fire extinguishing foam generator becomes particularly critical to relieve the safety concerns. In this work, a cryogenic fluid/bulk fluid mixing apparatus, composed of a horizontal channel and a conical spoiler in it, is developed to generate stable and homogeneous foam flow. The flow and temperature characteristics of the mixing flow

2D and 3D numerical permeability of fibrous media are studied based on Stokes and Stokes-Darcy flows simulated by a Finite Element Modelling (FEM). A monolithic approach stabilised by an Algebraic Sub-Grid Scale (ASGS) method and implemented in a FEM software (Z-set) is used. The 2D geometries have been generated according to ideal arrangements and 3D geometry are representative of a highly anisotropic

The clustering behaviour and settling velocity of bidisperse inertial particles with sub-millimetre diameters travelling in a turbulent open channel flow are investigated using the simultaneous particle image velocimetry and particle tracking velocimetry measurement technique. Instantaneous images of flow field and inertial particles are separated based on different wavelengths of light emitted by

Dynamics of inertial particles in homogeneous isotropic turbulence is investigated by means of numerical simulations that incorporate the effect of two-way interphase momentum transfer. The continuous phase is solved in the Eulerian approach employing Direct Numerical Simulations (DNS). The dispersed phase is treated using the Lagrangian approach along with the point-particle assumption. The main focus

During the operation of a seismic airgun source, a certain amount of compressed high-pressure air is released from the airgun chamber into the surrounding water, generating an expanding toroidal bubble attached to the airgun-body. The subsequent oscillations of the bubble generate low-frequency pressure waves, which are used to map the ocean subbottom, e.g., to locate oil and gas reserves. The bubble

In this research, the n-hexane jets discharged from a straight channel were studied numerically to reveal the development and characteristics of under-expanded flashing jets. Firstly, the development of flash boiling jets was investigated and compared to that of two-phase jets without phase transition. It was shown that the two-phase jets without phase transition can be under-expanded only if the flow

In this study, a single nucleation site was made on the upper surface of heated substrate, and small tracer particles suspended in water for flow visualization. Single vapor bubble dynamics and particle movements were recorded by high speed camera, then the flow field was quantitatively grasped by particle tracking visualization. Resulting of the visualization, in earlier stage of nucleate boiling

In order to mitigate the effects of salt water intrusion at sea locks, bubble screens are installed which act as a barrier between the dense sea water and the fresh water inland. In order to optimize the design of the bubble screen, in this study a state-of-the-art numerical model is developed based on the Euler-Lagrange CFD method which is expanded with a simple salt balance and concentration-density

Hydraulic jumps are oftentimes encountered in natural and human-made environments. The transition from supercritical to subcritical flow involves large energy dissipation rates and substantial air entrainment, preventing the use of monophasic flow measurement instrumentation. This paper presents an experimental study of a stable hydraulic jump with a Froude number of 4.25, utilizing novel intrusive

Among the many unknowns in the study of atomizing sprays, defining an unambiguous way to analyze turbulence is, perhaps, one of the most limiting ones. The lack of proper tools for the analysis of the turbulence field (e.g. specific one/two-point statistics, spectrum, structure functions) limits the understanding of the overall phenomenon occurring, impeding the correct estimation of motion scales

In the present paper, available experimental data and predictive correlations on cryogenic film boiling heat transfer are summarized and analyzed. A unified correlation formation, which could standardize the most of the existing heat transfer correlations, is used to perform comparison studies, and a series of validated correlations focusing on predicting cryogenic boiling events are reached. It demonstrates

Liquid fuel atomization in transverse uniform gaseous flow, i.e., crossflow, is widely utilized in aircraft engines and is considered an important aspect for engine development. The atomization-evaporation process of liquid fuel jet spray in the vicinity of a nozzle in crossflows is investigated by a detailed numerical simulation using an Eulerian/Lagrangian framework. The Eulerian framework is applied

We present data driven kinematic models for the motion of bubbles in high-Re turbulent fluid flows based on recurrent neural networks with long-short term memory enhancements. The models extend empirical relations, such as Maxey-Riley (MR) and its variants, whose applicability is limited when either the bubble size is large or the flow is very complex. The recurrent neural networks are trained on the

The co-current oil-water flow in a horizontal serpentine channel is studied experimentally by high-speed imaging. Due to the channel geometry, the flow exhibits curved streamlines, which can induce secondary flows and alter the flow pattern transition boundaries in comparison with those observed in straight channels. This can have important applications in the development of microfluidic mixing devices

This study aims to model the role of the viscoelastic properties of polymeric solutions in the jet mode of the electrospray process numerically. For this purpose, first, the computational challenges in front of a numerical investigation of such complex physics are explained, and the recent advances in rectifying these problems, especially the high Weissenberg instability, is described. Then, a numerical

A numerical study of a compressible air bubble rising in water with variable thermophysical properties is conducted. The coupled level set and volume of fluid method is adopted to track the interface. Empirical correlations in terms of temperature for thermophysical properties and equation of state for air are considered in the simulations. We simulate a compressible 3D static air bubble in water for

The collapse process of bubble cluster is closely related to bubble–bubble interaction. Theoretical analysis and numerical simulation are adopted to study the collapse of bubble cluster with various distributions. The key parameters for bubble collapse, including bubble quantity, volume fraction, and dimensionless pressure, are acquired by dimensional analysis. The effects of key parameters on collapse

We study the sedimentation of finite-size particles in quiescent wall-bounded Newtonian and shear-thinning fluids by interface resolved numerical simulations. The suspended phase consists of Non-Brownian rigid spherical particles with particle to fluid density ratio ρp/ρf=1.5 at three different solid volume fractions Φ=1%, 5% and 20%. Firstly, to focus on the effect of shear-thinning on the particle