scholarly journals 3D Numerical Modeling of Rigid Inclusion-Improved Soft Soils Under Monotonic and Cyclic Loading—Case of a Small-Scale Laboratory Experiment

2021 ◽  
Vol 11 (4) ◽  
pp. 1426
Author(s):  
Hung Van Pham ◽  
Daniel Dias
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Cyclic Loading ◽  
Rigid Inclusion ◽  
Research Work ◽  
Reinforced Soil ◽  
Numerical Results ◽  
Small Scale ◽  
3D Numerical Modeling ◽  
Soil Arching

This paper is based on small-scale laboratory tests (1:10) of a rigid inclusion-improved soil under normal gravity. A low area improvement ratio (2.4%) under monotonic and cyclic loading was used. 3D numerical calculations are performed to model these tests. The proposed numerical modeling is performed by the finite element method (FEM) using the ABAQUS software. A representative elementary volume model is suggested for reducing the calculation time. A hypoplastic constitutive model (HYP model) is applied for the load transfer platform (LTP). A total of three geometrical configuration cases of the experimental tests are numerically considered including a rigid slab over a mattress of 100 mm on the reinforced soil, a mattress of 100 mm on the reinforced soil, and a rigid slab over a mattress of 50 mm on the reinforced soil. The proposed numerical results are compared to the experimental data and the previous numerical results of Houda. The cyclic response of the systems is shown in terms of soil arching and settlements. The decrease in pile efficacy and the cumulative settlements are exhibited. The HYP model allows to better simulate the soil arching mechanisms inside the LTP than the CYsoil model used in the Houda’s research work. A good concordance between the proposed numerical results and the experimental data was obtained.

scholarly journals Modeling of Laminar Flows in Rough-Wall Microchannels

2005 ◽  
Vol 128 (4) ◽  
pp. 734-741 ◽  
Author(s):  
R. Bavière ◽  
G. Gamrat ◽  
M. Favre-Marinet ◽  
S. Le Person
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Numerical Modeling ◽  
Pressure Drop ◽  
Analytical Model ◽  
Analytical Approach ◽  
Laminar Flows ◽  
Numerical Results ◽  
Rough Wall ◽  
Relative Roughness

Numerical modeling and analytical approach were used to compute laminar flows in rough-wall microchannels. Both models considered the same arrangements of rectangular prism rough elements in periodical arrays. The numerical results confirmed that the flow is independent of the Reynolds number in the range 1–200. The analytical model needs only one constant for most geometrical arrangements. It compares well with the numerical results. Moreover, both models are consistent with experimental data. They show that the rough elements drag is mainly responsible for the pressure drop across the channel in the upper part of the relative roughness range.

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.

The study of the spreading of a drop of water on the surface of a metal by the methods of molecular dynamics

2012 ◽  
Vol 9 (2) ◽  
pp. 90-94
Author(s):  
E.F. Moiseeva ◽  
V.L. Malyshev
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Numerical Modeling ◽  
Water Vapor ◽  
Numerical Results ◽  
Dynamics Modeling ◽  
Molecular Dynamics Modeling ◽  
Water Metal ◽  
System Water ◽  
Metal Water

The results of molecular dynamics modeling for the system "water-metal-water vapor" are presented in the article. The method was verified by comparing numerical results with experimental data. The results of numerical modeling of the process of spreading a drop of water over the surface of platinum are presented.

Numerical Study on the Influence of Blockage Ratio on Hydrogen Turbulent Premixed Flames in a Small Scale Obstructed Chamber

2020 ◽  
Author(s):  
M. Elshimy ◽  
S. Ibrahim ◽  
W. Malalasekera
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Flame Structure ◽  
Premixed Flames ◽  
Numerical Results ◽  
Small Scale ◽  
Blockage Ratio ◽  
Increased Risk ◽  
The Impact ◽  
Flame Position

Abstract Although hydrogen is a clean and renewable fuel, there is still a need to understand and evaluate the potential risks posed in the event of an accidental explosion. This paper presents large eddy simulation (LES) numerical analysis for lean hydrogen premixed flames propagating inside a small laboratory combustion chamber with built in solid obstructions. The small-scale chamber is 0.625 litres in volume with three removable turbulence generating baffles and a square solid obstacle. A lean equivalence ratio of 0.7 is selected in this study. The LES model is utilised to investigate the influence of obstruction configuration and area blockage ratio on the flame characteristics and the generated combustion over-pressure. The LES turbulence technique is used with an in-house computational fluid dynamics (CFD) model for compressible flows. The numerical simulations are carried out with various arrangements of the baffle plates and a solid obstacle to examine the effects of the area blockage ratio and generated turbulence on the flame structure and generated over-pressure. Two different area blockage ratios of 0.24 and 0.5 are studied. Four configurations with different baffle arrangements are studied to examine the resulting turbulence effects on the generated over-pressure, flame position-time traces and flame transient speed following ignition. Direct comparisons are made between the different baffle/flow configurations to identify the various effects of an increased area blockage ratio. Numerical results showing the flame structure at various time windows after ignition are presented and compared with published experimental images. High speed laser induced fluorescence (LIF-OH) images of the reaction zones obtained from the experiments at a rate of 5 kHz provide the flame position data and convey the impact of the turbulence generated by the baffles and solid obstacle on the propagating flame structure [1]. The pressure is recorded at a rate of 25 kHz using a piezo-electric pressure transducer in the base plate of the chamber [2]. The rise in over-pressure as a result of increased turbulence due to additional baffles and an increased area blockage ratio is found to be consistent with experimental data. This is also found to be consistent for the flame position-time and speed-time traces across all configurations. Main points of interest such as the peak over-pressure, maximum rate of pressure rise and the flame propagation trends are also observed along with variations in flame speed as the flame interacts with the baffles and obstacles. Validation of the numerical results against available published experimental data conveys good agreement confirming the ability of the numerical model to predict numerical results for an increased area blockage ratio. Further numerical simulations are also carried out for flame/flow parameters where experimental data is unavailable due to physical limitations. Satisfactory agreement between numerical results and experimental data endorses further predictions for computational models in studying vented hydrogen explosions where there is an increased risk or limited experimental data.

Investigation of Turbulent Models for the Flow Field From a Typical Strut-Based Scramjet Combustor

2011 ◽  
Author(s):  
Shi-bin Luo ◽  
Wei Huang ◽  
Hui Qin ◽  
Zhen-guo Wang ◽  
Jun Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Shear Layer ◽  
Flow Fields ◽  
Numerical Results ◽  
Reflected Shock Wave ◽  
Small Scale ◽  
Reacting Flow ◽  
Scramjet Combustor ◽  
Turbulent Models

The two-dimensional coupled implicit RANS equations and three turbulent models have been employed to numerically simulate the nonreacting and reacting flow fields of a typical strut-based scramjet combustor, and the numerical results have been compared with the experimental data. At the same time, three different grid scales have been used to test the grid independence in the numerical simulations, namely the small scale (81,590 nodes), the moderate scale (98,510 nodes) and the large scale (147,470 nodes). The obtained results show that the RNG k-ε model is more suitable to numerically simulate the flow field in the scramjet combustor than the realizable k-ε model and the SST k-ω model, and the numerical results obtained by the moderate and large grid scales show reasonably better agreement with the experimental data. The quasi-diamond wave system is formed in both the nonreacting and reacting flow fields. In the reacting flow field, there are two clear strong shear layers generated between the fuel injection and the supersonic freestream, and at the intersection point between the shear layer and the reflected shock wave, the reaction zone is broader than anywhere else. In the corner formed between the upper surface of the strut and the shear layer, an expansion wave is clearly generated, and another also exists in the symmetrical corner.

Life Cycle Development of Successful Women-owned Enterprises

2020 ◽  
Vol 3 (4) ◽  
pp. 142-152
Author(s):  
Mohammad Waliul Hasanat ◽  
Kamna Anum ◽  
Ashikul Hoque ◽  
Mahmud Hamid ◽  
Sandy Francis Peris ◽  
...  
Keyword(s):  
Life Cycle ◽  
Data Collection ◽  
Research Work ◽  
Primary Data ◽  
Small Scale ◽  
Data Collection Process ◽  
Theoretical Finding ◽  
Successful Women ◽  
Two Phases ◽  
Life Cycle Development

In developing countries, the role of women in the business sector is continuously improving. As a result, female enterprises have also been encouraged in Pakistan. This study is based on life cycle development phases from which women-owned enterprises have to go through in order to become successful. As a primary data source, face-to-face interviews with owners of successful women-owned enterprises were preferred. The data collection process was divided into two phases i.e. Phase-I and Phase-II. After data collection, qualitative analysis has been performed using NVIVO. Findings provide both generic and specific factors involved in life cycle development of women-owned enterprises. This study provides a detailed view of life cycle development model followed by successful women enterprises. The outcome of this research work is a theoretical finding which can be utilized by entrepreneurs owning small scale enterprises to improve their level of performance. Findings can also be helpful for potentially talented women interested in setting up their own business.

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.

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