A One-Way Coupled Volume of Fluid and Eulerian-Lagrangian Method for Simulating Sprays

2016 ◽  
Author(s):  
Shaoping Quan ◽  
Peter Kelly Senecal ◽  
Eric Pomraning ◽  
Qingluan Xue ◽  
Bing Hu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fluid Flow ◽  
Nozzle Exit ◽  
Volume Of Fluid ◽  
Droplet Breakup ◽  
Fluid Field ◽  
Engine Combustion ◽  
Flow Information ◽  
Pros And Cons ◽  
The One

Volume of Fluid (VOF) and Eulerian-Lagrangian (EL)/Discrete Droplet Methods (DDM) are two of the most widely used methods in spray simulations. It is well known that these two methods have their pros and cons. VOF is good at capturing the transient detailed flow physics, while it is usually very expensive. EL is very efficient; however, to inject spray parcels, some experimental/pre-computed information is needed, such as rate of injection, and/or the parcel radius distributions, etc. It is often the case, the detailed fluid flow information at the nozzle exit, which is essential for downstream droplet breakup and coalescence, cannot be accounted in the EL method. In this paper, we developed a one-way coupled approach, in which VOF is employed to compute the detailed fluid field in the injector and this fluid information is then utilized by EL for the injection of parcels at the nozzle exit. The one-way coupled approach is used to calculate some ECN (Engine Combustion Network) spray cases, such as Spray A and Spray H. The simulated results are compared to the experimental data, and satisfactory agreement is obtained.

scholarly journals DETERMINING THE EFFECT OF NOZZLE GROOVE ON THE FLUID FLOW THROUGH VISCOUS 2D PLANAR FLUID

2021 ◽  
pp. 1-8
Author(s):  
Obai Younis ◽  
Reem Ahmed ◽  
Ali Hamdan ◽  
Dania Ahmed ◽  
Ali Ahmed ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Numerical Method ◽  
Surface Area ◽  
Nozzle Exit ◽  
New Approach ◽  
Numerical Stimulation ◽  
Flow Through ◽  
Different Dimensions ◽  
The One

The study aims to determine the effect of nozzle groove on fluid flow through viscous 2D planar fluid. To fulfil the study’s aim, numerical method was adopted to introduce grooves of different dimensions from the nozzle exit. The study adopts SoldWork software was used to design nozzles and introduce groove shaped nozzles, each consisting of six different designs. The nozzle base model used in this study was similar to the one used in a previous study. The procedure was performed with different pressures (8, 10, and 12 bar) at the similar firefighting nozzle. The velocities contours were predicted based on the choice of nozzle section during the numerical stimulation. The results of present study demonstrated a new approach that can be used for increasing velocity at various types of modified nozzles through grooves at different pressures and locations. For grooves, dimensions 1×1 (mm) and location 15 mm at 8 bar, 10 bar and 12 bars showed no effect on velocity as it reduces velocity by increasing surface area. The velocity increases with increasing pressure in proportion relationship. This clearly explains that the groove has no effect on velocity as it increases due to increase in pressure. This is because the groove reduces the velocity by increasing surface area. The study concludes that use of groove increases velocity of water that further improves nozzles operation.

Numerical Solution of Wavy-Stratified Fluid-Fluid Flow With the One-Dimensional Two-Fluid Model: Stability, Boundedness, Convergence and Chaos

2014 ◽  
Author(s):  
William D. Fullmer ◽  
Alejandro Clausse ◽  
Avinash Vaidheeswaran ◽  
Martin A. Lopez de Bertodano
Keyword(s):  
Experimental Data ◽  
Fluid Flow ◽  
Chaotic Behavior ◽  
Fluid Model ◽  
Linear Instability ◽  
Energy Transfer Mechanism ◽  
One Dimensional ◽  
Two Fluid Model ◽  
The One ◽  
Two Fluid

In this paper the one-dimensional two-fluid model is used to dynamically simulate slightly inclined fluid-fluid flow in a rectangular channel. By that, it is specifically meant that the solutions exhibit a wavy pattern arising from the inherent instability of the model. The conditions and experimental data of Thorpe (1969) are used for comparison. The linear instability of the model is regularized, i.e., made well-posed, with surface tension and axial turbulent stress with a simple turbulent viscosity model. Nonlinear analysis in an infinite domain demonstrates for the first time one-dimensional two-fluid model chaotic behavior in addition to limit cycle behavior and asymptotic stability. The chaotic behavior is a consequence of the linear instability (the long wavelength energy source) the nonlinearity (the energy transfer mechanism) and the viscous dissipation (the short wavelength energy sink). Since the model is chaotic, solutions exhibit sensitive dependence on initial conditions which results in non-convergence of particular solutions with grid refinement. However, even chaotic problems have invariants and the ensemble averaged water void fraction amplitude spectrum is used to demonstrate convergence and make comparisons to the experimental data.

scholarly journals Unbinding of Hyaluronan Accelerates the Enzymatic Activity of Bee Hyaluronidase

2011 ◽  
Vol 286 (41) ◽  
pp. 35699-35707 ◽  
Author(s):  
Attila Iliás ◽  
Károly Liliom ◽  
Brigitte Greiderer-Kleinlercher ◽  
Stephan Reitinger ◽  
Günter Lepperdinger
Keyword(s):  
Experimental Data ◽  
Quartz Crystal ◽  
Surface Loop ◽  
X Ray ◽  
Site Model ◽  
Substrate Interaction ◽  
Close Proximity ◽  
Binding Groove ◽  
The One ◽  
Best Fit

Hyaluronan (HA), a polymeric glycosaminoglycan ubiquitously present in higher animals, is hydrolyzed by hyaluronidases (HAases). Here, we used bee HAase as a model enzyme to study the HA-HAase interaction. Located in close proximity to the active center, a bulky surface loop, which appears to obstruct one end of the substrate binding groove, was found to be functionally involved in HA turnover. To better understand kinetic changes in substrate interaction, binding of high molecular weight HA to catalytically inactive HAase was monitored by means of quartz crystal microbalance technology. Replacement of the delimiting loop by a tetrapeptide interconnection increased the affinity for HA up to 100-fold, with a KD below 1 nm being the highest affinity among HA-binding proteins surveyed so far. The experimental data of HA-HAase interaction were further validated showing best fit to the theoretically proposed sequential two-site model. Besides the one, which had been shown previously in course of x-ray structure determination, a previously unrecognized binding site works in conjunction with an unbinding loop that facilitates liberation of hydrolyzed HA.

A Spray-Droplet Model for Diesel Combustion

1969 ◽  
Vol 184 (10) ◽  
pp. 28-35 ◽  
Author(s):  
J. Shipinski ◽  
P. S. Myers ◽  
O. A. Uyehara
Keyword(s):  
Experimental Data ◽  
Diesel Engine ◽  
Heat Release ◽  
Engine Speed ◽  
Chamber Pressure ◽  
Gas Temperature ◽  
Single Droplet ◽  
Burning Rates ◽  
Burning Model ◽  
The One

A spray-burning model (based on single-droplet theory) for heat release in a diesel engine is presented. Comparison of computations using this model and experimental data from an operating diesel engine indicate that heat release rates are not adequately represented by single-droplet burning rates. A new concept is proposed, i.e. a burning coefficient for a fuel spray. Comparisons between computations and experimental data indicate that the numerical value of this coefficient is nearly independent of engine speed and combustion-chamber pressure. However, the instantaneous value of the spray burning coefficient is approximately proportional to the instantaneous mass-averaged cylinder gas temperature to the one-third power.

A Silicon Micromachined Valve Driven by a Bi-Stable Electromagnetic Actuator

1999 ◽  
Author(s):  
S. Böhm ◽  
G. J. Burger ◽  
M. T. Korthorst ◽  
F. Roseboom
Keyword(s):  
Fluid Flow ◽  
Silicone Rubber ◽  
The Other ◽  
Dead Volume ◽  
Electromagnetic Actuator ◽  
Rubber Sheet ◽  
Rubber Layer ◽  
Sandwich Construction ◽  
The One ◽  
Valve Part

Abstract In this contribution a micromachined open/closed valve is presented which is driven by a conventionally manufactured bistable electromagnetic actuator. Basically the micromachined valve part, 7 × 7 × 1 mm3 in dimension, is a sandwich construction of two KOH etched wafers with a specially formulated silicone rubber layer in between. This rubber sheet forms a flexible flow path, which can be open and closed to control a fluid flow. In order to provide a large stroke of about 200 μm, a precision-engineered bi-stable electromagnetic actuator was selected. This actuator consists of a spring-biased armature that can move up and down in a magnetically soft iron housing, incorporating a permanent magnet and a coil. It will be shown that this combination of micromachined and precision-engineered components provides the required low dead volume on the one hand and a large actuator stroke on the other. Another benefit of the application of a bi-stable actuator is the fact that only energy is needed in order to switch between the open and closed state. Moreover, the large stroke makes the valve particle tolerant thus allowing media like cell suspensions and whole blood.

scholarly journals Kinetics of drying of basil leaves (Ocimum basilicum L.) in the infrared

2012 ◽  
Vol 16 (12) ◽  
pp. 1346-1352 ◽  
Author(s):  
Renata C. dos Reis ◽  
Ivano A. Devilla ◽  
Diego P. R. Ascheri ◽  
Ana C. O. Servulo ◽  
Athina B. M. Souza
Keyword(s):  
Experimental Data ◽  
Ocimum Basilicum ◽  
Coefficient Of Determination ◽  
Chisquare Test ◽  
The Mean ◽  
Drying Curves ◽  
The One ◽  
Increasing Temperature ◽  
Air Circulation ◽  
Kinetics Of

The objective of this paper was to model the drying curves of the leaves of basil (Ocimum basilicum L.) in the infrared at temperatures of 50, 60, 70 and 80 ºC and to evaluate the influence of drying temperature on the color of dried leaves. Drying was conducted in infrared dryer with temperature and greenhouse air circulation. Experimental data were fitted to eight mathematical models. The magnitude of the coefficient of determination (R²), the mean relative error (P), the estimated mean error (SE) and chisquare test (χ2) were used to verify the degree of fitness of the models. From the study it was concluded that: a) the behavior of the drying curves of basil leaves was similar to most agricultural products, the drying times in the infrared were less than the drying times in an oven with air circulation, b) the mathematical drying model proposed by Midilli et al. (2002) was the one which best adjusted to the experimental data, c) the diffusion coefficient ranged from 9.10 x 10-12 to 2.92 x 10-11 m² s-1 and d) the color of the samples was highly influenced by drying, becoming darker due to loss of chlorophyll with increasing temperature.

Grinding Fluid Flow Field Modeling and Multi-Parameter Numerical Analysis Based on Smooth Model

2010 ◽  
Vol 156-157 ◽  
pp. 948-955
Author(s):  
Guang Yao Meng ◽  
Ji Wen Tan ◽  
Yi Cui
Keyword(s):  
Fluid Flow ◽  
Numerical Analysis ◽  
Flow Field ◽  
Dynamic Pressure ◽  
Grinding Wheel ◽  
Lubricating Film ◽  
Fluid Field ◽  
Grinding Fluid ◽  
Smooth Model ◽  
Area Increase

Relative motion between grinding wheel and workpiece makes the lubricant film pressure formed by grinding fluid in the grinding area increase, consequently, dynamic pressure lubrication forms. The grinding fluid flow field mathematical model in smooth grinding area is established based on lubrication theory. The dynamic pressure of grinding fluid field, flow velocity and carrying capacity of lubricating film are calculated by the numerical analysis method. An analysis of effect of grinding fluid hydrodynamic on the total lifting force is performed, and the results are obtained.

Two-Fluid CFD Model of Adiabatic Air-Water Upward Bubbly Flow Through a Vertical Pipe With a One-Group Interfacial Area Transport Equation

2009 ◽  
Author(s):  
Deoras Prabhudharwadkar ◽  
Chris Bailey ◽  
Martin Lopez de Bertodano ◽  
John R. Buchanan
Keyword(s):  
Experimental Data ◽  
Transport Equation ◽  
Bubbly Flow ◽  
Interfacial Area ◽  
Correct Prediction ◽  
Interfacial Area Transport ◽  
One Dimensional ◽  
Interfacial Area Transport Equation ◽  
The One ◽  
Two Fluid

This paper describes in detail the assessment of the CFD code CFX to predict adiabatic liquid-gas two-phase bubbly flow. This study has been divided into two parts. In the first exercise, the effect of Lift Force, Wall Force and the Turbulent Diffusion Force have been assessed using experimental data from the literature for air-water upward bubbly flows through a pipe. The data used here had a characteristic near wall void peaking which was largely influenced by the joint action of the three forces mentioned above. The simulations were performed with constant bubble diameter assuming no bubble interactions. This exercise resulted in selection of the most appropriate closure form and closure coefficients for the above mentioned forces for the range of flow conditions chosen. In the second exercise, the One-Group Interfacial Area Transport equation was introduced in the two-fluid model of CFX. The interfacial area density plays important role in the correct prediction of interfacial mass, momentum and energy transfer and is affected by bubble breakup and coalescence processes in adiabatic flows. The One-Group Interfacial Area Transport Equation (IATE) has been developed and implemented for one-dimensional models and validated using cross-sectional area averaged experimental data over the last decade by various researchers. The original one-dimensional model has been extended to multidimensional flow predictions in this study and the results are presented in this paper. The paper also discusses constraints posed by the commercial CFD code CFX and the solutions worked out to obtain the most accurate implementation of the model.

scholarly journals A New Model Approach for Convective Wall Heat Losses in DQMOM-IEM Simulations for Turbulent Reactive Flows

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
Yeshaswini Emmi ◽  
Andreas Fiolitakis ◽  
Manfred Aigner ◽  
Franklin Genin ◽  
Khawar Syed
Keyword(s):  
Experimental Data ◽  
Heat Losses ◽  
Reacting Flow ◽  
Jet Flame ◽  
New Model ◽  
Turbulent Reactive Flows ◽  
Novel Method ◽  
The One ◽  
The Impact ◽  
Model Approach

A new model approach is presented in this work for including convective wall heat losses in the direct quadrature method of moments (DQMoM) approach, which is used here to solve the transport equation of the one-point, one-time joint thermochemical probability density function (PDF). This is of particular interest in the context of designing industrial combustors, where wall heat losses play a crucial role. In the present work, the novel method is derived for the first time and validated against experimental data for the thermal entrance region of a pipe. The impact of varying model-specific boundary conditions is analyzed. It is then used to simulate the turbulent reacting flow of a confined methane jet flame. The simulations are carried out using the DLR in-house computational fluid dynamics code THETA. It is found that the DQMoM approach presented here agrees well with the experimental data and ratifies the use of the new convective wall heat losses model.

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