Papers by Keyword: Discrete Phase Model

Abstract: This study investigated the influence of nanoparticle material type and weight percentage on the flow behaviour of underfill encapsulation in Ball Grid Array (BGA) assemblies. As BGA packages are increasingly used in high-density and high-performance electronic devices, ensuring reliable solder joint encapsulation becomes critical. While nanoparticle-reinforced underfills enhance thermal and mechanical performance, they also introduce complexities in flow behaviour due to changes in viscosity and particle–fluid interactions. To address this, a multiphase numerical model was developed using the Finite Volume Method (FVM) and the Discrete Phase Model (DPM) in ANSYS Fluent to simulate the transient flow of underfill resin reinforced with Al₂O₃, SiO₂, and TiO₂ nanoparticles at varying weight percentages (5%, 10%, 15%, and 20%). The simulation captured the progression of fluid fill at intervals (25%, 50%, 75%, 95%) and measured total flow time. Results revealed Al₂O₃-based underfill consistently achieved faster flow, with the shortest 95% fill time recorded at 69.84 seconds for a 17.16% weight load concentration, while SiO₂-based underfill had the slowest flow, with times exceeding 74 seconds at 20% loading. These differences were attributed to variations in nanoparticle density and dispersion behaviour. A Random Forest regression model trained on simulation data further confirmed that nanoparticle type and concentration were the most significant predictors of flow time. These findings demonstrate that optimal nanoparticle selection can balance mechanical reinforcement with manufacturability. The results offer practical insights for electronics manufacturers aiming to improve process throughput and reliability in advanced packaging by selecting suitable nanoparticle-enhanced underfill formulations.Keywords: Underfill encapsulation, Nanoparticle reinforcement, Finite Volume Method, Discrete Phase Model, Artificial Neural Network.

Abstract: A pulverized-coal boiler is a type of boiler that is commonly seen in power plants. During an operation, a portion of the coal is converted to ash. The consequence is a cause of slagging on the furnace wall and a considerable loss in heat transfer performance. In coal-fired power plants, slagging is one of the most common causes of maintenance issues. This problem can be resolved by using a water soot blower cleaning system. It shoots a high-pressure jet of water through a hole in the side of the furnace’s wall to clean the opposite wall surfaces. This study presents a Computational Fluid Dynamics (CFD) investigation of the water soot blower trajectory with a flow field in full-scale boiler. Multiphase-flow simulation is utilized. The turbulence model couple and Discrete Phase Model are used to analyze flow field in boiler and water soot blower trajectory, respectively. The aim is to accurately determine an injection angle degree for the water soot blower. The CFD results are compared with the experiment of water soot blower shooting in Cold Air Velocity Test (CAVT) conditions. The results of the study show that the simulation results agree with the experimental data. Moreover, the velocity profile of numerical study shows that the effect of flow field in boiler has little effect on the water soot blower trajectory.

Abstract: The performance of Electrostatic Precipitator (ESP) is significantly affected by complex flow distribution. Recent years, many numerical models have been developed to model the particle motion in the electrostatic precipitators. The computational fluid dynamics (CFD) code FLUENT is used in description of the turbulent gas flow and the particle motion under electrostatic forces. The gas flow are carried out by solving the Reynolds-averaged Navier-Stokes equations and turbulence is modeled by the k-ε turbulence model. The effect of electric field is described by a series equations, such as the electric field and charge transport equations, the charged particle equation, the charge conservation equation, the mass and momentum equations of gas, the mass and momentum equations of particle and so on. The particle phase is simulated by using Discrete Phase Model (DPM). The simulations showed that the particle trajectory inside the ESP is influenced by both the aerodynamic and electrostatic forces. The simulated results have been validated by the established data.

Abstract: This paper shows the numerical simulation of the problem that electrical submersible pump impeller is vulnerable to particle impact erosion in the water under the condition of the water injection of the same wells in oil field. This simulation is based on Fluent of CFD software, which has built a geometric model of electric submersible pump impeller flow field, and given the calculation of the internal flow field of the impeller, and showed the solution of the motion track of the particles in the turbulent by the way of discrete phase model and random orbit, and calculated the erosion by the micro cutting model by particless, and compared the field test data with the simulation results which proved the reliability of numerical simulation method.

Abstract: Gas-liquid flow in a stirred vessel was simulated numerically with computational fluid dynamics(CFD). Gas was treated as discrete phase and described by discrete phase model (DPM), while the liquid was considered as a continuum and solved under Euler reference frame. The liquid velocity, gas holdup and gas residence time distribution in the stirred vessel were predicted. The simulation results show that gas dispersion in the stirred vessel is very non-uniformity and high gas holdup is found in the centre of the stirred vessel and vortexes while relatively low in bottom region and region between two impellers. Liquid velocity has great influence on bubble residence time and size distributions.

Abstract: In this paper, a swirl nozzle is established to disperse superfine powder aerodynamically. And Reynolds stress model (RSM) is adopted to simulate the strongly swirling, compressible and transonic gas flow in the nozzle and its rear. Combined with discrete phase model (DPM), the concentration distribution of particle group in size of 2.5μm is studied. The simulated results show that, the distribution of swirl strength is determined basically by the nozzle structure, while the total pressure has little effect on it; compared with an irrotational nozzle, the swirl nozzle could achieve a better dispersing effect for superfine powder.

Abstract: Considering the demand of precision in mould structural surface polishing method, a new method based on soft abrasive flow machining(SAFM) was proposed, which was supposed to achieve polydirectional and multi-angle cutting acting on the surface of the workpiece by utilizing the irregular motion of both wear particles and the media in turbulence flow. Thus as the monodirectional marks on the machined surfaces was eliminated, the disadvantage in machining precision in conventional abrasive flow machining(AFM) method would be overcome. According to the particle distribution characteristics of SAFM, a two-phase dynamic model of abrasive flow oriented to SAFM combined with Discrete Phase Model(DPM) was built to analog simulation with the software Fluent. Sequently the mechanism of ultraprecision machining towards mould structural surface was analyzed briefly. Simulation results show that the abrasive efficiency along the flow passage can be influenced by the development of turbulence and the distribution of dispersed phase. Thus there a specific region can be obtained in the passage in which the abrasive efficiency is relatively stable.

Abstract: Precalciner, in which endothermic raw meal calcination and exothermic fuel combustion proceed simultaneously, is a key equipment in dry process of cement production. To increase the precalcination degree and reduce the energy consumption, more and more attentions have been paid on modeling gas-solid flow field in precalciners. However, most of them aimed at just qualitative studies lacking in necessary further quantitative analysis of precalciner performance parameters. In this paper, combining qualitative studies and quantitative analysis, the gas-solid flow field was carried out aiming at an actual precalciner under operational-based boundary conditions. In Euler coordinate system the gas phase is expressed with k-ε model, in Lagrange coordinate system the solid phase is expressed with Discrete Phase Model(DPM), and the random effects of turbulence on the particle dispersion is accounted for with Discrete Random Walk (DRW) model. The predicted gas velocity field agrees well with the measured result, and the calculated raw meal concentration distribution is consistent with the actul condition. The results predicted that there is a simple spraying-liked flow field in the precalciner, with not only a non-uniform particle dispersion condition but also a low solid residence-time and residence-time ratio between solid and gas.