Assessment of an Eulerian multi-fluid VOF model for simulation of multiphase flow in an industrial Ruhrstahl–Heraeus degasser

2019 ◽  
Vol 116 (6) ◽  
pp. 617
Author(s):  
Gujun Chen ◽  
Qiangqiang Wang ◽  
Shengping He
Keyword(s):  
Multiphase Flow ◽  
Molten Steel ◽  
Mixing Time ◽  
Interface Tracking ◽  
Discrete Phase Model ◽  
Eulerian Model ◽  
Ansys Fluent ◽  
Vof Model ◽  
Discrete Phase ◽  
Sharp Interfaces

An Eulerian multi-fluid VOF model, the coupling of the Eulerian model and the “VOF” interface tracking method, offered by ANSYS Fluent has been first applied to investigate the complex multiphase flow in an industrial Ruhrstahl–Heraeus (RH) degasser. The idea of this study is to use the Eulerian model in the regions of the domain where the argon bubbles are dispersed in molten steel; in the regions of the domain where the sharp interfaces between the steel and slag or argon are of interest, the “VOF” method is adopted. The calculated flow characteristic, mixing time and circulation flow rate of molten steel in the RH degasser agree well with the observations reported in literature. Compared with the widely accepted Eulerian method and the discrete phase model–volume of fluid (DPM–VOF) coupled method, the Eulerian multi-fluid VOF model demonstrates the suitability for modeling the multiphase flow in the RH degasser where both dispersed and sharp interfaces are present.

scholarly journals Two-Dimensional Analysis Of Flow Field And Associated Scour Parameters At Downstream Of Weir With And Without Sloping Apron

2019 ◽  
Vol 8 (6) ◽  
pp. 1027-1036
Keyword(s):  
Flow Structure ◽  
Particle Tracking ◽  
Control Structure ◽  
Model Simulation ◽  
Maximum Velocity ◽  
Discrete Phase Model ◽  
Eulerian Model ◽  
Ansys Fluent ◽  
Flow Features ◽  
Discrete Phase

The downstream scour of the control structure is a more common and very complex issue in river engineering. Flow structure in the vicinity of the control structure is entirely different from other parts of the river. Ansys Fluent Multiphase Eulerian model combined with hybrid Dense Discrete Phase Model (DDPM) provides much accurate and precise view of flow structure. This model provides a better understanding of flow structure, and it is associated scour development at upstream and downstream. Model simulation is performed on the trapezoidal weir and trapezoidal weir with sloping apron platforms to compare the flow structure, and it is associated scour. The erosion is computed by Mc Laury erosion model, and particle tracking is done using DDPM through a Lagrangian approach stimulate the movement of particles within the flow domain, velocity and other properties. This research focused on delivering much better anticipation about all flow features and sediment particle tracking captured in a closer manner. In this analysis with the trapezoidal weir, the velocity reached around 0.835 ms -1. However, as in the case of trapezoidal weir with sloping apron, the maximum velocity goes approximately 0.505 ms-1 which are nearly equal to inlet velocity. From the analysis, the sloping apron proves to be significant in protecting the downstream side of the control structure

scholarly journals Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042110080
Author(s):  
Zheqin Yu ◽  
Jianping Tan ◽  
Shuai Wang
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Multiphase Flow ◽  
Experimental Verification ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Phase Model ◽  
Force Model ◽  
Discrete Phase Model ◽  
Discrete Phase

Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.

Enhancing Turbine Deposition Prediction Capability With Conjugate Mesh Morphing

2021 ◽  
Author(s):  
Christopher P. Bowen ◽  
Jeffrey P. Bons
Keyword(s):  
Effective Conductivity ◽  
Road Dust ◽  
Discrete Phase Model ◽  
Ansys Fluent ◽  
Mesh Morphing ◽  
Average Flow Velocity ◽  
Impingement Jet ◽  
Discrete Phase ◽  
The Ohio State University ◽  
Original Metal

Abstract A framework for performing mesh morphing in a conjugate simulation in the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent is presented and validated. A procedure for morphing both the fluid and solid domains to simulate the protrusion of deposit into the fluid while concurrently altering and adding to the solid regions is detailed. The ability to delineate between the original metal sections of the solid and the morphed regions which represent deposit characteristics is demonstrated. The validity and predictive capability of the process is tested through simulation of a canonical impingement jet. A single over-sized impingement jet (6.35 mm) at 894 K and an average flow velocity of 56.5 m/s is used to heat a nickel-alloy target plate. One gram of 0-5 μm Arizona Road Dust (ARD) is delivered to the target and a Particle Shadow Velocimetry (PSV) technique is used to capture the transient growth of the deposit structure on the target. Thermal infrared images are taken on the backside of the target and synchronized with the PSV images. The experiment is modeled computationally using the Fluent Discrete Phase Model (DPM) and the Ohio State University (OSU) Deposition Model for sticking prediction. The target is morphed according to the particulate volume prediction. The deposit regions are assigned an effective conductivity (keff) representative of porous deposit, and the fluid and thermal computations are reconverged. 10 mesh morphing iterations are performed accounting for the first half of the experiment. The morphed deposit volume and height are compared to the experiment and show reasonable agreement. The backside target temperatures are also compared, and the simulations show the ability to predict the reduction in temperature that occurs as the growing deposit insulates the metal surface. It is demonstrated that the assignment of unique thermal conductivities to the deposit and metal cells within the solid is critical. With a more robust and accurate implementation of the deposit keff, this conjugate mesh morphing framework shows potential as a tool for predicting the thermal impact of deposition.

scholarly journals Numerical simulation of multiphase flow in ventilation mill and channel with louvers and centrifugal separator

2011 ◽  
Vol 15 (3) ◽  
pp. 677-689 ◽  
Author(s):  
Mirko Kozic ◽  
Slavica Ristic ◽  
Mirjana Puharic ◽  
Boris Katavic
Keyword(s):  
Multiphase Flow ◽  
Numerical Simulations ◽  
Volume Fraction ◽  
Complex Geometry ◽  
Mixture Distribution ◽  
Flow Simulation ◽  
Centrifugal Separator ◽  
Discrete Phase Model ◽  
Discrete Phase ◽  
Lagrange Approach

This paper presents the results of numerical flow simulation in ventilation mill of Kostolac B power plant, where louvers and centrifugal separator with adjustable blade angle are used. Numerical simulations of multiphase flow were performed using the Euler-Euler and Euler-Lagrange approach of ANSYS FLUENT software package. The results of numerical simulations are compared with measurements in the mill for both types of separators. Due to very complex geometry and large number of the grid cells, convergent solution with the Eulerian model could not be obtained. For this reason the mixture model was employed resulting in very good agreement with measurements, concerning the gas mixture distribution and velocity at the main and secondary burners. There was large difference between the numerical results and measurements for the pulverized coal distribution at the burners. Taking into consideration that we analyzed dilute mixture with very low volume fraction of the coal, the only choice was the Euler-Lagrange approach, i.e. discrete phase model limited to volume fraction of the discrete phase less than 10-12%. Obtained distributions of the coal at the burners agree well for both types of separators.

On Scouring Efficiency of Flush Waves in Sewers: A Numerical and Experimental Study

2019 ◽  
Author(s):  
Maryam Alihosseini ◽  
Paul Uwe Thamsen
Keyword(s):  
Sediment Transport ◽  
Multiphase Model ◽  
Discrete Phase Model ◽  
Sluice Gate ◽  
Ansys Fluent ◽  
Sediment Bed ◽  
Complex Process ◽  
Discrete Phase ◽  
Sand And Gravel ◽  
The Waves

Abstract In sewer sediment management, the removal of depositions using hydraulic flushing gates has recently gotten great attention. Despite numerous investigations, the complex process of sediment transport under flushing waves is not yet well understood. The present work aims to calibrate and validate a coupled computational fluid dynamics and discrete element method (CFD-DEM) to study the fluid-sediment interaction in sewers. The CFD part of the simulation was carried out in the software Ansys Fluent which is two-way coupled to the DEM software EDEM. The multiphase model volume of fluid (VOF) was used to simulate the flushing wave, while the sediments were handled as DEM particles using the discrete phase model (DPM). To validate the 3D model, experimental work has been performed in a circular laboratory pipe with sand and gravel of different size distributions. A construction of a sluice gate was installed to realize the flushing event, which is similar to a dam-break wave. The evolution of the sediment bed and the scouring efficiency of the waves were examined under different flushing conditions. The results showed that the CFD-DEM method could be used to investigate the performance of flushing devices and various features of sediment transport which are not easy to obtain in the laboratory or field.

scholarly journals Experimental validation of CFD simulations of bioaerosol movement in a mechanically ventilated airspace

2019 ◽  
pp. 5.01-5.14
Author(s):  
Amy La ◽  
Qiang Zhang
Keyword(s):  
Steady State ◽  
Mesh Size ◽  
Respiratory Syndrome Virus ◽  
Discrete Phase Model ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Mechanically Ventilated ◽  
Discrete Phase ◽  
Optimal Mesh ◽  
Ventilation Rates

A CFD (computational fluid dynamics) model was developed to simulate the movement of bioaerosols in mechanically-ventilated chambers and the results were validated with experiments. Liquid aerosols containing Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) were artificially generated in the chambers. Bioaerosol concentration was monitored with an optical particle counter until steady-state conditions were achieved (aerosols containing viruses are referred to as bioaerosols in this paper). Four treatments with two ventilation rates and two bioaerosol generation rates were tested. The standard k-ɛ turbulence model and a discrete phase model with unsteady tracking was used in an ANSYS Fluent CFD model to simulate the airflow and bioaerosol movement until steady-state was reached. A mesh refinement test was performed to select an optimal mesh size for simulations. The CFD simulations showed good agreement with the measured bioaerosol concentrations at steady-state with differences of 2% to 8%, normalized mean square error of 0.01 to 0.19, and fractional bias of 0.02 to 0.08. Simulations and validation during the transient phase could not be verified because of limited measurement locations.

scholarly journals The Operation of a Three-Bladed Horizontal Axis Wind Turbine under Hailstorm Conditions—A Computational Study Focused on Aerodynamic Performance

Inventions ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 2
Author(s):  
Dimitra Douvi ◽  
Eleni Douvi ◽  
Dionissios P. Margaris
Keyword(s):  
Wind Turbine ◽  
Cross Sections ◽  
Computational Study ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Horizontal Axis ◽  
Discrete Phase Model ◽  
Horizontal Axis Wind Turbine ◽  
Ansys Fluent ◽  
Discrete Phase

The aim of this study is the aerodynamic degradation of a three-bladed Horizontal Axis Wind Turbine (HAWT) under the influence of a hailstorm. The importance and originality of this study are that it explores the aerodynamic performance of an optimum wind turbine blade during a hailstorm, when hailstones and raindrops are present. The commercial Computational Fluid Dynamics (CFD) code ANSYS Fluent 16.0 was utilized for the simulation. The first step was the calculation of the optimum blade geometry characteristics for a three-bladed rotor, i.e., twist and chord length along the blade, by a user-friendly application. Afterwards, the three-dimensional blade and the flow field domain were designed and meshed appropriately. The rotary motion of the blades was accomplished by the application of the Moving Reference Frame Model and the simulation of hailstorm conditions by the Discrete Phase Model. The SST k–ω turbulence model was also added. The produced power of the wind turbine, operating in various environmental conditions, was estimated and discussed. Contours of pressure, hailstone and raindrop concentration and erosion rate, on both sides of the blade, are presented. Moreover, contours of velocity at various cross sections parallel to the rotor are demonstrated, to understand the effect of hailstorms on the wake behavior. The results suggest that the aerodynamic performance of a HAWT degrades due to impact and breakup of the particles on the blade.

CFD Study of Surface Flow and Gas Dispersion From a Subsea Gas Release

2014 ◽  
Author(s):  
Qing Qing Pan ◽  
Jan Erik Olsen ◽  
Stein Tore Johansen ◽  
Mark Reed ◽  
Lars Roar Sætran
Keyword(s):  
Oil And Gas ◽  
Surface Flow ◽  
Lagrangian Model ◽  
Correct Prediction ◽  
Gas Release ◽  
Discrete Phase Model ◽  
Model Framework ◽  
Gas Dispersion ◽  
Vof Model ◽  
Discrete Phase

With increasing subsea oil and gas activities, the safety is challenged by accidental gas release. This can be caused by leakage from gas transport pipelines or blowouts from oil and gas wells. Risk assessment of such events is associated to the correct prediction of gas flux and gas distribution through the ocean surface and the resulting surface flows. A quantitative multiphase CFD model can satisfy such needs. Bubbles can be tracked by discrete phase model (DPM), using a parcel-based Lagrangian approach. Capturing the free surface formed by surfacing bubble plumes can be handled by a volume of fluid (VOF) model. This constitutes an Eulerian-Lagrangian model framework combining the DPM and VOF models. The model is presented and validated by experiments of a gas release in 7 m deep test basin. Results from modelling and experiments are consistent.

scholarly journals Numerical simulation of liquid fuel prechamber ignition

2021 ◽  
Author(s):  
Levon Larson
Keyword(s):  
Turbulence Modeling ◽  
Spray Angle ◽  
Navier Stokes ◽  
Discrete Phase Model ◽  
Lean Burn ◽  
Penetration Length ◽  
Ansys Fluent ◽  
Eddy Simulation ◽  
Discrete Phase ◽  
Rans Models

A Computational Fluid Dynamics (CFD) model was built that simulates the transient, compressible, reacting, multi-phase environment that exists within a reciprocating engine's combustion chamber(s). ANSYS Fluent v13.0 was used with the Euler-Lagrangian Discrete Phase Model (DPM), the Shell autoignition model, and the Large Eddy Simulation (LES) method of turbulence modeling. Validation of the spray dynamics was performed by comparing simulation results with experiments of liquid and vapour penetration length of an n-Heptane spray experiment done by Sandia National Laboratories. It was found that LES produced more accurate results than several Reynolds Averaged Navier-Stokes (RANS) models. The Shell autoignition model was coded to function with C10.17H19.91 and compared with experimental ignition results in a Rapid Compression Machine (RCM) environment. All of the above models were then combined to simulate a directly-fueled lean-burn combustion prechamber configuration wherein the effects of spray angle, timing, and duration were studied.

CFD MODELING OF PNEUMATIC OIL BARRIER

2014 ◽  
Vol 2014 (1) ◽  
pp. 300087
Author(s):  
Qing Qing Pan ◽  
Stein Tore Johansen ◽  
Mark Reed ◽  
Lars Roar Satran
Keyword(s):  
Fluid Dynamic ◽  
Turbulent Energy ◽  
Parallel Line ◽  
Frame Of Reference ◽  
Cfd Modeling ◽  
Discrete Phase Model ◽  
Oil Boom ◽  
Oil Slick ◽  
Vof Model ◽  
Discrete Phase

Pneumatic oil barriers (so called “bubble oil boom (BOB)”) are based on the rise of air bubbles which are injected from the submerged parallel line spargers (McClimans et al., 2012). Local outward flows are formed when the bubbles and entrained water reach the sea surface, and thereby could counterbalance the opposing sea current to retain the spilled oil. It could function alone or work together with a traditional oil boom to improve the recovery effectiveness. A multiphase Computational Fluid Dynamic model, which couples volume of fluid (VOF) and discrete phase model (DPM) approach together with an enhanced k-epsilon model, is developed. Trajectories of bubbles are computed in the Lagrangian frame of reference, exchanging momentum and turbulent energy with water and oil slick, represented in the Eulerian frame of reference. The interface between atmosphere, water and oil slick is captured by the VOF model. The model is applied to meso-scale experiments in McClimans et al. (2012) for validation. The validated numerical model can provide improved basis for the further design of BOB system.

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