Validation of a Numerical Model for Dynamic Three-Dimensional Railway Bridge Analysis by Comparison with a Small-Scale Laboratory Model

2017 ◽  
Vol 6 (2) ◽  
pp. 61-85
Author(s):  
P Bucinskas ◽  
J. Sneideris ◽  
L. Agapii ◽  
L.V. Andersen
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Laboratory Model ◽  
Small Scale ◽  
Railway Bridge

Removal of Contaminants by Induced Air Flow Inside Structures

2001 ◽  
Author(s):  
G. Ziskind ◽  
V. Dubovsky ◽  
R. Letan
Keyword(s):  
Natural Convection ◽  
Air Flow ◽  
Three Dimensional ◽  
Solar Irradiation ◽  
Laboratory Model ◽  
Small Scale ◽  
Real Size ◽  
Removal Of Contaminants ◽  
Enclosed Space ◽  
Vertical Duct

Abstract The present paper discusses the continuous removal of contaminants from enclosed spaces by means of induced air flow. The air flow is caused by natural convection in a heated horizontal or vertical duct. The heating of the duct can be achieved by absorption of solar irradiation or any other means. As a result, a steady air flow can be induced inside the duct and the enclosed space, as has been shown by the authors for a small scale laboratory model. Three dimensional numerical simulations are performed for various kinds of real-size structures, including one-story detached buildings and underground enclosed spaces. The k-epsilon turbulence model is used in the simulations. The results yield detailed flow field inside the enclosures at various configurations of the openings. Rate of air change is calculated both for the whole enclosure and for the layers above the floor where the contaminants tend to accumulate. Optimal design of the systems is discussed.

Three-Dimensional Modeling of Wave-Induced Seabed Response Around a Semi-Buried Pipeline: A Small-Scale Case

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Jianfeng Zhu ◽  
Hongyi Zhao
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
The Body ◽  
Navier Stokes ◽  
Small Scale ◽  
Buried Pipeline ◽  
Consolidation Process ◽  
Soil Response ◽  
Wave Flume ◽  
Wave Induced

Abstract In this paper, a three-dimensional integrated numerical model for a small-scale case of wave-induced oscillatory soil response around a semi-buried pipeline (PORO-WSSI-PIPE 3D) is proposed. In this model, we combine the Reynolds-averaged Navier–Stokes (RANS) equations for the 3D wave motions and the Biot’s consolidation equations for a porous elastic seabed foundation through pressure continuity at common boundaries, with pipeline being an elastic and impermeable medium. The computational results are validated through comparison with previous analytical solutions and laboratory wave flume tests, obtaining good agreement. Following validation, the numerical model is applied to simulate wave-seabed-pipeline interaction with different obliquities between pipeline and incident wave, varying from 30 deg to 90 deg. Snapshots of wave-seabed-pipeline interaction, as well as dynamic pore pressure distributions at typical locations in the vicinity of a semi-buried pipeline, are obtained and analyzed. The three-dimensional consolidation process of seabed under gravitational forces including the body forces of a pipeline is also discussed.

scholarly journals Numerical Study of Violent Impact Flow Using a CIP-Based Model

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Qiao-ling Ji ◽  
Xi-zeng Zhao ◽  
Sheng Dong
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Large Scale ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Small Scale ◽  
Surface Boundary ◽  
Two Phase ◽  
Constrained Interpolation

A two-phase flow model is developed to study violent impact flow problem. The model governed by the Navier-Stokes equations with free surface boundary conditions is solved by a Constrained Interpolation Profile (CIP)-based high-order finite difference method on a fixed Cartesian grid system. The free surface is immersed in the computation domain and expressed by a one-fluid density function. An accurate Volume of Fluid (VOF)-type scheme, the Tangent of Hyperbola for Interface Capturing (THINC), is combined for the free surface treatment. Results of another two free surface capturing methods, the original VOF and CIP, are also presented for comparison. The validity and utility of the numerical model are demonstrated by applying it to two dam-break problems: a small-scale two-dimensional (2D) and three-dimensional (3D) full scale simulations and a large-scale 2D simulation. Main attention is paid to the water elevations and impact pressure, and the numerical results show relatively good agreement with available experimental measurements. It is shown that the present numerical model can give a satisfactory prediction for violent impact flow.

scholarly journals Research on Influence of Deep Foundation Pit Excavation and Dewatering on Pile Foundation of Railway Bridge

2021 ◽  
Vol 283 ◽  
pp. 01019
Author(s):  
Liu Tianyun ◽  
Yu Changyi ◽  
Zhu Nan
Keyword(s):  
Numerical Model ◽  
Pile Foundation ◽  
Three Dimensional ◽  
Railway Bridge ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Maximum Settlement ◽  
Limit Value ◽  
Construction Optimization

The three-dimensional numerical model of the foundation pit engineering is established, and the fluid-structure coupling method is used to calculate the settlement of the pile foundation of the adjacent railway bridge caused by the excavation and dewatering of the foundation pit. The results show that the settlement range of the soil around the foundation pit reaches 140m, and the pile foundation of the railway bridge is within the influence range, but the maximum settlement value does not exceed the limit value specified in the design. The method used in this paper provides effective guidance for the construction optimization of the same type of projects and reduces the project cost.

Modeling Progressive Settlement of a Railway Bridge Transition

2016 ◽  
Author(s):  
Stephen T. Wilk ◽  
Timothy D. Stark
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Surface Profile ◽  
Railway Bridge ◽  
Wheel Load ◽  
Bridge Abutment ◽  
The Impact

This paper illustrates the impact of progressive settlement on a railway bridge transition using a three-dimensional dynamic numerical model that includes the train truck, rails, ties, ballast, subgrade, and bridge abutment and structure. A settlement law that relates tie load to ballast settlement is presented and demonstrated using an iterative fashion to evaluate bridge transition response to 28 MGT. The results illustrate: (1) development of the commonly observed dip about 2.5 to 3.7 m (8 to 12 feet) from the entrance bridge abutment, (2) tie-ballast gaps progressively increase in height and expand to ties outwards from the bridge abutment, (3) a redistribution of load to ties outwards from the bridge abutment as tie-ballast gaps develop and increase, and (4) a ballast surface profile that attempts to minimize tie loads by evenly distributing the wheel load amongst adjacent ties.

scholarly journals Investigating Effect of Different Parameters of the Submerged Vanes on the Lateral Intake Discharge Located in the 180 Degree Bend Using the Numerical Model

2017 ◽  
Vol 3 (11) ◽  
pp. 1176 ◽  
Author(s):  
Ali Sarhadi ◽  
Ehsan Jabbari
Keyword(s):  
Numerical Modeling ◽  
Numerical Model ◽  
Flow Line ◽  
Numerical Models ◽  
Three Dimensional ◽  
Laboratory Model ◽  
Effective Parameters ◽  
Lateral Channel ◽  
Flow Part ◽  
Submerged Vanes

Intakes are widely used for flow diversion and its control in the open channels or rivers. During passing flow, part of the suspended sediment along with the flow enters the lateral channel and deposits in the lateral intake channel entrance, causing a change in the direction of the flow line towards the shore in front of the reservoir, which reduces the intake efficiency. Submerged vanes are small hydraulic structures that, by creating a secondary flow in their downstream, cause changes in the flow pattern and guide line to the drainage span, and the most important parameters affecting sediment input to the waterfall is the ratio of flow rate. Investigating a laboratory model has high costs and times, which in some cases cannot be justified, therefore, suitable numerical models can be proposed for such options. In this study, using Flow3D, three-dimensional numerical modeling of the flow was calibrated and verified using existing data and numerical modeling accuracy, the relative error of the numerical model was determined. In this study, all effective parameters including submerged vanes type, submerged vanes number, submerged vanes size and Froude number changes in the main channel and type of submerged vanes layout have been investigated. The results of the numerical model show that the angle of inclination of 60 degrees in the entrance intake and the chassis layout in the Froude numbers 0.21-0.33 will result in the most lateral intake discharge.

Extrusion-Based 3D Printing for Pharmaceuticals: Contemporary Research and Applications

2019 ◽  
Vol 24 (42) ◽  
pp. 4991-5008 ◽  
Author(s):  
Mohammed S. Algahtani ◽  
Abdul Aleem Mohammed ◽  
Javed Ahmad
Keyword(s):  
Cosmetic Surgery ◽  
Fused Deposition Modeling ◽  
Personalised Medicine ◽  
Organ Transplant ◽  
Three Dimensional ◽  
Dosage Forms ◽  
Release Profile ◽  
Small Scale ◽  
Drug Release Profile ◽  
Fused Deposition

Three-dimensional printing (3DP) has a significant impact on organ transplant, cosmetic surgery, surgical planning, prosthetics and other medical fields. Recently, 3 DP attracted the attention as a promising method for the production of small-scale drug production. The knowledge expansion about the population differences in metabolism and genetics grows the need for personalised medicine substantially. In personalised medicine, the patient receives a tailored dose and the release profile is based on his pharmacokinetics data. 3 DP is expected to be one of the leading solutions for the personalisation of the drug dispensing. This technology can fabricate a drug-device with complicated geometries and fillings to obtain the needed drug release profile. The extrusionbased 3 DP is the most explored method for investigating the feasibility of the technology to produce a novel dosage form with properties that are difficult to achieve using the conventional industrial methods. Extrusionbased 3 DP is divided into two techniques, the semi-solid extrusion (SSE) and the fused deposition modeling (FDM). This review aims to explain the extrusion principles behind the two techniques and discuss their capabilities to fabricate novel dosage forms. The advantages and limitations observed through the application of SSE and FDM for fabrication of drug dosage forms were discussed in this review. Further exploration and development are required to implement this technology in the healthcare frontline for more effective and personalised treatment.

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