We investigate the phase change effect at the thin film interface with broken time-reversal-symmetry falling down an inclined flat wall. We consider the impact of evaporation and as well as condensation at the fluid-vapor interface separately. The non-zero odd part of the Cauchy stress tensor with the odd viscosity coefficient, which arises due to broken-time-reversal-symmetry, adds an attractive characteristic

Atomization of liquid metal is an essential process in a variety of production methods such as spray forming or laser sintering. A critical part of all atomization processes is the breakup of single droplets, also termed secondary atomization. While it has been widely analyzed for conventional liquids, studies focusing on the influence of the specific properties of liquid metals remain rare. To identify

Phase change in multiphase flows occurs in many natural and industrial applications, e.g., rain formation, internal combustion engines, heat exchangers, multiphase reactors, etc. In dense two-phase flows, quantitative experimental results are scarce due to the complexity of the configuration and experimental techniques limitations. Hence, the interest in the direct numerical simulation of such flows

During the operation of a proton exchange membrane (PEM) fuel cell water is produced as a byproduct of electrochemical reactions. As the produced water passes through the porous structure of the electrodes and enters the flow channels, liquid–gas two-phase flow forms within the flow channels. If a reliable model that can accurately predict the pressure drop is available, then the two-phase flow pressure

Characterizing the trapped phase in porous media is essential for many engineering applications, such as enhanced oil recovery, nuclear storage, and geological sequestration of CO2. This study aims to study the distribution, evolution, and influencing factors of the remaining oil in the process of water flooding at the pore scale. The single-connected pore space model was established by reconstructing

Slug flow has drawn attention for industrial applications because it is one of the most prevalent and problematic two-phase flows due to severe pressure fluctuations. The effects of rib elements installed at the inner walls of a channel on the flow structure and pressure fluctuations are experimentally investigated with particular focus on how the rib elements alter slugging phenomena as compared with

In the present study, we experimentally investigated the freely rising of bubble-in-chain and the evolution of bubble-induced flow for a quiescent fluid. Quantitative data on bubble morphology, kinematics, and bubble-induced flow dynamics were obtained by combining the methods of shadowgraphy and laser-induced-fluorescence particle image velocimetry (PIV/LIF). Under the current experimental condition

In this article, a statistical study on transverse permeability of random fibrous medium is performed. For that purpose, numerous random numerical microstructures are generated with constant or randomly varying fibre radii. Their statistical representativity with respect to experimental data is first briefly discussed. Flow simulations are then performed on these digital microstructures to retrieve

Coherent vortex structures in subgrid scale (SGS) motions are important for preferential concentration and collision of particles with small and intermediate Stokes number (Xiong et al., 2019). In this study, a new large eddy simulation (LES) strategy that combines wavelet filtered large eddy simulation with a differential filter SGS model is proposed. First, a wavelet filtered direct numerical simulation

This work focuses on the basic interactions between a vortex and an interface separating two incompressible fluids. Specifically, we investigate how vorticity produced at an interface influences the dynamics of this very same interface and how the produced vorticity engenders small scales and small droplets. A critical Weber number Wec(1) exists discriminating the conditions upon which the interface

In this paper, an analysis of susceptibility of wave structure in annular flow to small high-frequency oscillations is carried out. Downward adiabatic air-water flow at atmospheric pressure is studied in a vertical 11.7 mm pipe. The range of superficial gas velocities is 0 – 70 m/s and the range of wetting densities is 1.6 – 4.6 cm2/s. Spatiotemporal records of liquid film thickness are obtained with

Identifying two-phase flow patterns is fundamental to successfully design and subsequently optimize high-precision heat transfer equipment, given that the heat transfer efficiency and pressure gradients occurring in such thermo-hydraulic systems are dependent on the flow structure of the working fluid. This paper shows that with visualization data and artificial neural networks, the flow pattern images

Freezing of water droplet is widely seen and important in the fields of aerospace, cold energy storage, and power production. To investigate the freezing process of a sessile water droplet on a horizontal cold plate, a theoretical model was developed. Different from previously reported models, the effects of supercooling and gravity on the physical properties and the water droplet profile are both

This study presents numerical simulations for particle-laden gas–solid flows in horizontal circular pipes to identify the key flow regimes as a function of the main dimensionless parameters. A Euler–Lagrangian approach is employed, using direct numerical simulations (DNS) coupled with a Lagrangian particle tracking (LPT) method, to consider the drag, gravitational and lift forces on particles, as well

The homogeneous mixture model with noble-abel stiffened-gas (NASG) equation of state is applied to solve the numerical simulation of compressible multi-phase flows. The gravity and surface tension forces are included, and a preconditioning scheme is used to improve the convergence of the low speed. In this study, oscillations of an elliptical drop were used to verify that the surface tension force

Droplet impact on a solid surface occurs in many natural phenomena and industrial applications such as raindrop impact on the ground, drip irrigation, spray cooling, spray coating, inkjet printing, etc. Importantly, in several cases such as aerosol transfer from the sea, oxygen dissolution, and thermally sprayed coatings the impinging droplets contain air bubble dealing with liquid-bubble-solid interaction

Boiling of highly wetting fluids is of great interest to thermal management of high-powered electronic devices, enhancement of which conventionally relies on functional modifications of surface shape and structure so as to promote bubble generation and growth. In this paper we attempt to combine the approach of porous texturing with a novel technique of surface wettability engineering to enhance saturated

Interfacial area concentration (IAC) and bubble size distribution (BSD) are two important parameters in two-phase flow simulations. High-speed tomography techniques, mainly including wire-mesh sensor and ultrafast X-ray imaging in this stage, are advanced measurement devices, which can measure the instantaneous phase distribution in the cross-section with high spatial resolution. In previous studies

Owing to high-turbulent and shear flow caused by the converging-diverging geometry, Venturi channels can serve as bubble generators to produce fine bubbles efficiently. Taking the advantage of simplicity in structure, high reliability, and low power consumption, Venturi-type bubble generators have broad application potential in various fields. Under a specified flow condition, the performance of a

Enhancement of the electric field on mixture has attached wide interests owing to its advantages in the terrestrial and space applications. In this paper, the dispersion characteristics of bubbles in leaky-dielectric liquid were investigated with a novel designed capillary electrode in the presence of a non-uniform electric field, employing high-speed photography and with a focus on the electrohydrodynamic

1D, 2D and 3D numerical simulations were carried out with the Reynolds-Averaged Navier-Stokes equations (RANS) for horizontal oil-water core-annular flow in which the oil core stays laminar while the water layer is turbulent. The turbulence is described with the Launder-Sharma low-Reynolds number k−ϵ model. The simulation results are compared with experiments carried out in our lab in a 21 mm diameter

An experimental study was conducted on the flow characteristics and turbulence suppression in vertically issued bubbly jets with low void fraction (less than 1%, Re = 3,172). The effect of bubble distributions on the flow characteristics of the bubbly jet was investigated using planar Laser-Induced Fluorescence (PLIF) in the same measurement plane as Particle Image Velocimetry (PIV) for the phase separation

Particle-resolved simulation is performed to study the drag force on arrays of ellipsoidal particles with a temperature difference with respect to the surrounding fluid. The effect of particle shape, arrangement, solid volume fraction and particle temperature is examined. We found that the particle shape and arrangement strongly influence the drag coefficient CD when the particle volume fraction ϕ

This study concerns a two-dimensional liquid drop surrounded by gas and attached to a sinusoidally vibrating wall. Gravity is neglected and the moving contact lines are modelled using a Navier-type boundary condition at the wall and a prescribed contact angle, θ¯, which can take any value in the range 0<θ¯<π. The vibration amplitude, and hence the departure from equilibrium of the drop, is assumed

The turbulent breakup of bubbles is a complex phenomenon present in a large number of engineering applications and natural processes. Simplified models are essential to better understand the interaction between turbulent eddies and bubbles. Probably the simplest one is that given by a vortex ring colliding with a single bubble. With this motivation, in the present work we perform three-dimensional

Multiphase flows management is a major challenge in many space applications given the different gravity levels involved. While many of the numerical investigations of liquid-gas phenomena deal with the radial bubble behavior and thus the heat exchange, only a few studies have been conducted on the translational motion of bubbles. We present a numerical investigation of the translational motion of gas

A new atomization method to destabilize an annular liquid sheet ejected from a gas turbine engine injector, called the Rayleigh-Taylor instability induced atomization (RTA) is proposed. In contrast to the traditional coaxial atomizers, a liquid is allowed to flow through an annular passage in the axial direction and air is allowed to impinge on the liquid sheet in the radial direction. Due to this

The nonequilibrium properties and strong spatiotemporal long-range correlations in gas-solid suspensions were analyzed systematically by discrete particle simulation in periodic domains. The effective interphase slip velocity is significantly larger than the particle terminal velocity, the particle velocity distribution function is non-Maxwellian with a high-energy tail and the solid concentration

The work is devoted to the numerical simulation of the known problem of a normally incident shock wave – dense layer of particles interaction and the phenomenon of the pressure rise on the wall under the layer. The novelty of the work is in the numerical approach which is based on the Godunov solver for the Baer-Nunziato equations and the pressure relaxation procedure which takes into account intergranular

An airlift pump facility of 200 m length was designed and constructed; pump experiments were conducted for water and two types of highly-viscous shear-thinning slurries. The primary objective of this study is to obtain quantitative data on the performance characteristics of slurries for deep-sea mining. Experimental results showed the capability of the airlift pump for the slurries. The airflow rates

Flash atomization can occur in rocket thrusters operated at near vaccum conditions just prior to ignition when cryogenic propellants are injected into the reaction chamber. Although the morphology of flashing sprays has been widely studied, empirical observations of the primary breakup mechanisms at the micro-scale are currently not feasible. Still, further analysis of the micro-scales is necessary

The existing nucleate pool boiling correlations have theoretical footings and their usefulness is restricted by the failure to effectively account for the surface effect. To tackle this problem, a high-fidelity approach based on deep learning has been developed to predict the nucleate boiling surfaces subject to various surface roughness. The proposed model accounts for the effect of surface roughness

In the present study, the multiphase volume distribution problem, where there can be an arbitrary number of phases, is addressed using a consistent and conservative volume distribution algorithm. The proposed algorithm satisfies the summation constraint, the conservation constraint, and the consistency of reduction. The first application of the volume distribution algorithm is to determine the Lagrange

The objective of this paper is to study sheet/cloud cavitation dynamics in fluid-structure interaction by experimental and numerical methods. The high-speed camera is applied to observe the cavitating flow structures and the Laser Doppler Vibrometer is used to characterize the vibration. A hydrodynamic load cell is applied to measure the lift and drag static force. The results present different cavitating

Experimental observations and measurements concerning falling, necking, and break-up characteristics of a single droplet from a horizontal tube to the adjacent tube are performed using a high-speed digital camera. The droplet flow with a low Reynolds number at several tube-spacing are adopted in experiments. The morphological changes of droplet flow are presented in detail. With the increase of tube

Processes of spray dispersion around bluff bodies in wind are central to many engineering applications; notably the design of wildfire sprinkler systems and spray cooling systems for urban areas. Simulation methods such as computational fluid dynamics (CFD) have been widely used for the prediction and analysis of such wind-body-spray interactions. However, there has been a lack of high-quality experimental

We study numerically and experimentally the stability of the transonic flow focusing used in serial femtosecond crystallography (SFX) to place complex biochemical species into the beam focus. Both the numerical and experimental results indicate that the minimum flow rate for steady jetting increases slightly with the gas stagnation pressure. There is a remarkable agreement between the stability limit

We propose a model for large-eddy simulation (LES) of decaying isotropic turbulence laden with droplets with diameter of Taylor length-scale. The main challenge in creating LES models for such flow is that the presence of the droplets introduces additional subgrid-scale (SGS) closure terms to the filtered governing equations of motion of the flow. By processing available DNS data (Dodd & Ferrante,

Bubbly drag reduction in turbulent flows is of significant interest in the naval industry. In this paper, we investigate experimentally the transition from bubbly drag increase to bubbly drag reduction at moderate to high Reynolds numbers and analyze the contributions of different mechanisms. The experiments were performed in a water tunnel. To achieve Reynolds numbers of the boundary layer, of the

This paper considers the stability of an unsteady, two-phase flow with heat and mass transfer. The model problem is motivated by loss of coolant accidents in nuclear power plants. For the example problem, two flow geometries are considered: inverted annular flow boiling and an annular mist flow. The model is comprised of coupled Mathieu equations so that stability can be determined using a Floquet

This paper describes the atomization process of a liquid sheet generated by a coaxial swirl injector and it establishes a theoretical breakup model to predict the Sauter mean diameter (SMD) in the entire spray field. The two stage breakup model, which includes Kelvin-Helmholtz (K-H) and Rayleigh-Taylor (R-T) instability, is established and combined with the dispersion relation obtained by linear stability

Behaviour of self-pressurized nitrous oxide (N2O) injection through a sharp-edged channel intended to replicate a rocket motor injector has been studied using carbon dioxide (CO2) as an analog fluid. Experimental data was collected from 14 separate experiments which varied pressure upstream and downstream of the injection channel. The experimental data was used to determine the accuracy of previously

This study focuses on the characterisation of downwards annular gas-liquid (air-water) flows, by employing a combination of advanced laser-based and capacitance-based measurement methods. A variant of laser-induced fluorescence (LIF), referred to as structured-planar laser-induced fluorescence (S-PLIF), eliminates biases commonly encountered during film-thickness measurements of gas-liquid flows, due

An experimental study to establish a one-on-one correspondence between microlayer dynamics and growth process of single vapor bubble under nucleate pool boiling regime has been presented. The transient evolution of microlayer and the corresponding vapor bubble growth have been simultaneously recorded using a thin film interferometer and one of the gradients-based imaging techniques, namely rainbow

Self-pulsation boundaries that spray switches between stable and self-pulsated behaviors are experimentally obtained under water and air flow conditions for a liquid-centered swirl coaxial injector configured with different recess lengths. The underlying mechanisms responsible for self-pulsation are investigated comprehensively. Results show that for the non-recessed injector, self-pulsation only occurs

Rapid depressurization of a stagnant liquid below its prevailing saturation brings it to a metastable superheated state. Thermodynamic equilibrium is regained through a rapid evaporation or flashing which starts in a thin layer at the free surface and continues to propagate downward by nucleation and evaporation in the subsequent layers of superheated liquid below it. Secondary nucleation (from spurious

A liquid-vapor phase change lattice Botlzmann method was used to simulate the dynamics of two bubbles during the lateral coalescence on solid surfaces in nucleate boiling. The evolution of bubble shapes and the departure diameter of bubbles were compared with experimental data. Comparisons show good agreement. The heat fluxes under nucleating, coalescing, growing and departing bubbles were simulated

In experiments of the collapse and rebound of a laser-produced cavitation bubble near a wall, a so-called “counterjet”, i.e., a jet in the direction away from the bubble and the wall, was typically observed during the rebound phase for a certain range of stand-off distances. It was previously suggested that a mechanism for the formation of the counterjet might be cavitation inception that follows the

A new pigging approach with SDS (Sodium dodecyl sulfate) surfactant was proposed for foam drainage in the gathering pipelines with wet gas production, especially for the pipeline section with a great pigging risk. For this purpose, the loop of gas-liquid two-phase flow with a 3 ° slightly upward pipeline was designed. The flow pattern characteristics of gas-liquid two-phase flow were collected by a

The behaviour of compound drops rising at high Reynolds numbers, roughly 60 to 700, was studied experimentally for a wide range of diameter ratios and three different combinations of the internal and external fluids. Two rising regimes were identified, namely a rectilinear and an oscillatory trajectory. The governing effects in each motion regime were discussed. The compound drops presented mild shape

In this paper, we demonstrate the application of a generalised Fully Lagrangian Approach to the simulation of polydisperse gas-evaporating droplet flows. The paper focuses on the proposed methodology for modelling the dispersed phase, droplets, in both steady and transient cases. To account for polydispersity, the set of Lagrangian variables is extended to include the droplet size, and the droplet

Two-phase flows of refrigerants commonly occur in a multitude of systems in the power and process industries, including heat pumps, organic flash cycle,... These flows often have to pass through T-junctions to divide the inlet stream into two outlet streams. Herein, phase maldistribution can occur, meaning that the vapour qualities in the outlet are not equal to the inlet vapour quality. Undesired

High concentration tailings suspension is attracting increasingly more attention due to its environmental and economic benefits. The interaction between non-Newtonian carrier and coarse particles in high concentration suspensions is still poorly understood, particularly in a turbulent regime. This paper presents a DNS-DEM model for weakly turbulent coarse-particle non-Newtonian suspensions. Matching

While air injection has already been widely studied for stagnant water at low air injection rates for circular injectors, limited data is available on gas in liquid cross-flows injected through slots at high air flow rates. The key purpose of this work is to observe the evolution of bubble swarm characteristics for simple geometries such that, by correlation rules, these characteristics can be projected

The ubiquity of two-phase systems has rendered them a subject of prime importance especially from numerical perspectives. Among several methods described in the literature, which are generally classified as sharp or diffuse interface methods, phase-field (diffuse interface) method has been at the paramount of several recent investigations owing to its several advantages, primarily to handle complex

We report an experimental investigation of turbulence in bubble plumes released in unstratified quiescent water. The focus is to study the detailed turbulent statistics and the budget terms in the equations of turbulent kinetic energy (TKE), particularly about their distributions in the radial direction of bubble plumes compared to those in the single-phase momentum jets and buoyant plumes. Two types

Detail characterization of the liquid jet core in a model cross-stream airblast atomizer by application of the Optical Connectivity (OC) technique is the goal of the present paper. The unique ability of the technique in imaging the fluorescence signal exclusively from the jet core region facilitates simultaneous visualization of the liquid jet from the side- and the front-view with high background