scholarly journals Simulation studies on the RF gun saturated emission

2020 ◽  
pp. 103-106
Author(s):  
Sergey M. Polozov ◽  
Vladimir I. Rashchikov
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Electron Bunch ◽  
Positive Charge ◽  
Cathode Region ◽  
Numerical Results ◽  
Simulation Studies ◽  
Rf Gun

The emission of a short high charged electron bunch in a radiofrequency gun was simulated. The numerical model is supplemented by a positive charge arising and dynamically changing during emission in the cathode region The numerical results are compared with experimental data.

scholarly journals Investigation of the effects of opening size and location on punching shear resistance of flat slabs using Abaqus

2021 ◽  
Vol 15 (4) ◽  
pp. 136-147
Author(s):  
Nguyen Tuan Trung ◽  
Pham Thanh Tung
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Numerical Study ◽  
Shear Resistance ◽  
Design Principles ◽  
Numerical Results ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Flat Slabs ◽  
Abaqus Model

The paper presents a numerical study on the effects of opening size and location on punching shear resistance of flat slabs without drop panels and shear reinforcement using ABAQUS. The study proposes an ABAQUS model that is enable to predict the punching shear resistance of flat slabs with openings. The model is validated well with the experimental data in literature. Using the validated numerical model, the effects of opening size and location on the punching shear resistance of flat slabs are then investigated, and the numerical results are compared with those predicted by ACI 318-19 and TCVN 5574:2018. The comparison between experimental and numerical results shows that the ABAQUS model is reliable. The punching shear resistances calculated by ACI 318-19 and TCVN 5574:2018 with different opening sizes and locations are agreed well to each other, since the design principles between two codes now are similar.

Biomass pyrolysis modeling of systems at laboratory scale with experimental validation

2018 ◽  
Vol 28 (2) ◽  
pp. 413-438 ◽  
Author(s):  
Stefano Cordiner ◽  
Alessandro Manni ◽  
Vincenzo Mulone ◽  
Vittorio Rocco
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Fast Pyrolysis ◽  
Experimental System ◽  
High Energy ◽  
Numerical Results ◽  
Small Scale ◽  
Content Type ◽  
Slow Pyrolysis ◽  
Bio Oil

Purpose Thermochemical conversion processes are one of the possible solutions for the flexible production of electric and thermal power from biomass. The pyrolysis degradation process presents, among the others, the interesting features of biofuels and high energy density bio-oil production potential high conversion rate. In this paper, numerical results of a slow batch and continuous fast pyrolyzers, are presented, aiming at validating both a tridimensional computational fluid dynamics-discrete element method (CFD–DEM) and a monodimensional distributed activation energy model (DAEM) represents with data collected in dedicated experiments. The purpose of this paper is then to provide reliable models for industrial scale-up and direct design purposes. Design/methodology/approach The slow pyrolysis experimental system, a batch of small-scale constant-pressure bomb for allothermic conversion processes, is presented. A DEM numerical model has been implemented by means of a modified OpenFOAM solver. The fast pyrolysis experimental system and a lab scale screw reactor designed for biomass fast pyrolysis conversion are also presented along with a 1D numerical model to represent its operation. The model which is developed for continuous stationary feeding conditions and based on a four-parallel reaction chemical framework is presented in detail. Findings The slow pyrolysis numerical results are compared with experimental data in terms of both gaseous species production and reduction of the bed height showing good predictive capabilities. Fast pyrolysis numerical results have been compared to the experimental data obtained from the fast pyrolysis process of spruce wood pellet. The comparison shows that the chemical reaction modeling based on a Gaussian DAEM is capable of giving results in very good agreement with the bio-oil yield evaluated experimentally. Originality/value As general results of the proposed activities, a mixed experimental and numerical approach has demonstrated a very good potential in developing design tools for pyrolysis development.

A numerical model for the analysis of unsteady train braking and releasing manoeuvres

2009 ◽  
Vol 223 (3) ◽  
pp. 305-317 ◽  
Author(s):  
L Cantone ◽  
E Crescentini ◽  
R Verzicco ◽  
V Vullo
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Numerical Results ◽  
Computationally Efficient ◽  
Braking System ◽  
Key Features

In this article, a numerical model for the pneumatic braking system of traditional freight trains is developed and tested. The validation of the results is performed through the comparison of the numerical results with analogous experimental data. The model has proved to be reliable and computationally efficient either for simple braking and releasing manoeuvres or for complex/transient manoeuvres. This model has been included in the software TrainDy, and thanks to its key features it has gained the Union Internationale Chemin de fer certification.

Experimental and Numerical Study of Cavitation in Centrifugal Pumps

2010 ◽  
Author(s):  
Erfan Niazi ◽  
M. J. Mahjoob ◽  
Ardeshir Bangian
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Mass Flow Rate ◽  
Computer Simulations ◽  
Mass Flow ◽  
Flow Rate ◽  
Numerical Study ◽  
Numerical Results ◽  
Centrifugal Pumps ◽  
Cavitation Threshold

Cavitation in pumps is one of the most important causes of damage to pumps impellers/inducers. A numerical model is developed here to simulate the pump hydraulics in different conditions. Experiments are also conducted to validate the computer simulations. To verify the numerical model, the h–m˙ (head versus mass flow rate) of the model is compared with the experimental data. The system is then run under cavitation state. Two methods are applied to monitor the cavitation threshold: first by using stroboscope and observing cavitation bubbles through the transparent casing of the pump and second by checking the NPSHA value for cavitation based on ISO3555. The paper then compares the experimental and numerical results to find the strengths and weaknesses of the numerical model.

Modeling Heat Transfer of the Air Gap between Human Body and Clothing

2011 ◽  
Vol 332-334 ◽  
pp. 1611-1614
Author(s):  
Ying Ke ◽  
Yun Yi Wang ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Numerical Model ◽  
Human Skin ◽  
Human Body ◽  
Air Gap ◽  
Numerical Results ◽  
Unsteady State ◽  
State Heat ◽  
Set Up

An unsteady-state heat transfer numerical model of the microclimate between human skin and clothing is set up. Air-gap thickness less than 17mm is considered. Matlab pde toolbox is chosen to compute the numerical model. The numerical results of the model agrees well with a set of published experimental data.

Numerical Simulation of Irregular Wave Forces on a Horizontal Cylinder

2016 ◽  
Author(s):  
Ankit Aggarwal ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Hans Bihs ◽  
Øivind Asgeir Arnsten
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Numerical Model ◽  
Circular Cylinder ◽  
Wave Generation ◽  
Numerical Results ◽  
Irregular Waves ◽  
Wave Forces ◽  
Ghost Cell ◽  
Irregular Wave

In the present study, the irregular wave forces on a fully submerged circular cylinder are investigated using the open-source computational fluid dynamics (CFD) model REEF3D. A complete three dimensional representation of the ocean waves requires the consideration of the sea surface as an irregular wave train with the random characteristics. The numerical model uses the incompressible Reynolds-averaged Navier-Stokes (RANS) equations together with the continuity equation to solve the fluid flow problem. Turbulence modeling is carried out using the two equation k-ω model. Spatial discretization is done using an uniform Cartesian grid. The level set method is used for computing the free surface. For time discretization, third-order total variation diminishing (TVD) Runge Kutta scheme is used. Ghost cell boundary method is used for implementing the complex geometries in the numerical model. MPI is used for the exchange of the value of a ghost cell. Relaxation method is used for the wave generation. The numerical model is validated for the irregular waves for a wave tank without any structure. Further, the numerical model is validated by comparing the numerical results with the experimental data for a fully submerged circular cylinder under regular waves and irregular waves. The numerical results are in a good agreement with the experimental data for the regular and irregular wave forces. The JONSWAP spectrum is used for the wave generation. The free surface features and kinematics around the cylinder is also presented and discussed.

A numerical study of breaking waves in the surf zone

1998 ◽  
Vol 359 ◽  
pp. 239-264 ◽  
Author(s):  
PENGZHI LIN ◽  
PHILIP L.-F. LIU
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Surf Zone ◽  
Breaking Waves ◽  
Numerical Results ◽  
Long Distance ◽  
The Mean

This paper describes the development of a numerical model for studying the evolution of a wave train, shoaling and breaking in the surf zone. The model solves the Reynolds equations for the mean (ensemble average) flow field and the k–ε equations for the turbulent kinetic energy, k, and the turbulence dissipation rate, ε. A nonlinear Reynolds stress model (Shih, Zhu & Lumley 1996) is employed to relate the Reynolds stresses and the strain rates of the mean flow. To track free-surface movements, the volume of fluid (VOF) method is employed. To ensure the accuracy of each component of the numerical model, several steps have been taken to verify numerical solutions with either analytical solutions or experimental data. For non-breaking waves, very accurate results are obtained for a solitary wave propagating over a long distance in a constant depth. Good agreement between numerical results and experimental data has also been observed for shoaling and breaking cnoidal waves on a sloping beach in terms of free-surface profiles, mean velocities, and turbulent kinetic energy. Based on the numerical results, turbulence transport mechanisms under breaking waves are discussed.

Modelling of catalyst pellet deactivation

1985 ◽  
Vol 50 (11) ◽  
pp. 2381-2395
Author(s):  
Alena Brunovská ◽  
Ján Buriánek ◽  
Ján Ilavský ◽  
Ján Valtýni
Keyword(s):  
Experimental Data ◽  
Numerical Results ◽  
Benzene Hydrogenation ◽  
Alumina Catalyst ◽  
Temperature Changes ◽  
Catalyst Pellet ◽  
Model Equations ◽  
Catalytic Poison

The diffusion and the shell progressive models of deactivation caused by irreversible chemisorption of a catalytic poison are presented for a single catalyst pellet. The method for solution of the model equations is proposed. The numerical results are compared with experimental data obtained by measuring concentration and temperature changes due to thiophene poisoning in benzene hydrogenation over a nickel-alumina catalyst.

An implicit scheme for simulation of free surface non-Newtonian fluid flows on dynamically adapted grids

2021 ◽  
Vol 36 (3) ◽  
pp. 165-176
Author(s):  
Kirill Nikitin ◽  
Yuri Vassilevski ◽  
Ruslan Yanbarisov
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Fluid Flows ◽  
Numerical Results ◽  
Implicit Scheme ◽  
New Approach

Abstract This work presents a new approach to modelling of free surface non-Newtonian (viscoplastic or viscoelastic) fluid flows on dynamically adapted octree grids. The numerical model is based on the implicit formulation and the staggered location of governing variables. We verify our model by comparing simulations with experimental and numerical results known from the literature.

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