scholarly journals An Improved One-Dimensional Model for Liquid Slugs Traveling in Pipelines

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Arris S. Tijsseling ◽  
Qingzhi Hou ◽  
Zafer Bozkuş
Keyword(s):  
Experimental Data ◽  
Flow Separation ◽  
Parameter Variation ◽  
Numerical Results ◽  
Driving Pressure ◽  
Dimensional Model ◽  
Liquid Slug ◽  
Straight Pipe ◽  
One Dimensional ◽  
1D Model

An improved one-dimensional (1D) model—compared to previous work by the authors—is proposed, which is able to predict the acceleration and shortening of a single liquid slug propagating in a straight pipe with a downstream bend. The model includes holdup at the slug's tail and flow separation at the bend. The obtained analytical and numerical results are validated against experimental data. The effects of holdup, driving pressure and slug length are examined in a parameter variation study.

An Improved 1D Model for Liquid Slugs Travelling in Pipelines

2014 ◽  
Author(s):  
Arris S. Tijsseling ◽  
Qingzhi Hou ◽  
Zafer Bozkuş
Keyword(s):  
Experimental Data ◽  
Flow Separation ◽  
Parameter Variation ◽  
Numerical Results ◽  
Liquid Slug ◽  
Straight Pipe ◽  
One Dimensional ◽  
1D Model

An improved one-dimensional (1D) model — compared to previous work by the authors — is proposed which is able to predict the acceleration and shortening of a single liquid slug propagating in a straight pipe with a downstream bend. The model includes holdup at the slug’s tail and flow separation at the bend. The obtained analytical and numerical results are validated against experimental data. The effects of the improvement and of holdup are examined in a parameter variation study.

scholarly journals Improved One-Dimensional Models for Rapid Emptying and Filling of Pipelines

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Arris S. Tijsseling ◽  
Qingzhi Hou ◽  
Zafer Bozkuş ◽  
Janek Laanearu
Keyword(s):  
Experimental Data ◽  
Skin Friction ◽  
Large Scale ◽  
Numerical Results ◽  
Driving Pressure ◽  
Liquid Column ◽  
One Dimensional ◽  
Laboratory Setup ◽  
Dimensional Models

Improved one-dimensional (1D) models—compared to previous work by the authors—are proposed which are able to predict the velocity, length, and position of the liquid column in the rapid emptying and filling of a pipeline. The models include driving pressure and gravity, skin friction and local drag, and holdup at the tail and gas intrusion at the front of the liquid column. Analytical and numerical results are validated against each other, and against experimental data from a large-scale laboratory setup.

Effective Shear Area in One Dimensional Ship Hull Finite Element Models to Predict Natural Frequencies of Vibration

2013 ◽  
Author(s):  
Osvaldo Pinheiro de Souza e Silva ◽  
Severino Fonseca da Silva Neto ◽  
Ilson Paranhos Pasqualino ◽  
Antonio Carlos Ramos Troyman
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Numerical Results ◽  
Computational Method ◽  
Scale Model ◽  
Dimensional Model ◽  
One Dimensional ◽  
Shear Area

This work discusses procedures used to determine effective shear area of ship sections. Five types of ships have been studied. Initially, the vertical natural frequencies of an acrylic scale model 3m in length in a laboratory at university are obtained from experimental tests and from a three dimensional numerical model, and are compared to those calculated from a one dimensional model which the effective shear area was calculated by a practical computational method based on thin-walled section Shear Flow Theory. The second studied ship was a ship employed in midshipmen training. Two models were made to complement some studies and vibration measurements made for those ships in the end of 1980 decade when some vibration problems in them were solved as a result of that effort. Comparisons were made between natural frequencies obtained experimentally, numerically from a three dimensional finite element model and from a one dimensional model in which effective shear area is considered. The third and fourth were, respectively, a tanker ship and an AHTS (Anchor Handling Tug Supply) boat, both with comparison between three and one dimensional models results out of water. Experimental tests had been performed in these two ships and their results were used in other comparison made after the inclusion of another important effect that acts simultaneously: the added mass. Finally, natural frequencies experimental and numerical results of a barge are presented. The natural frequencies numerical results of vertical hull vibration obtained from these approximations of effective shear areas for the five ships are finally discussed.

Numerical study of the flow field characteristics over a backward facing step using k-kl-ω turbulence model: comparison with different models

2018 ◽  
Vol 15 (1) ◽  
pp. 173-180 ◽  
Author(s):  
Yasser M. Ahmed ◽  
A.H. Elbatran
Keyword(s):  
Experimental Data ◽  
Fluid Mechanics ◽  
Turbulence Model ◽  
Flow Separation ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Numerical Results ◽  
Backward Facing Step ◽  
Content Type ◽  
Case Comparison

Purpose This paper aims to investigate numerically the turbulent flow characteristics over a backward facing step. Different turbulence models with hybrid computational grid have been used to study the detached flow structure in this case. Comparison between the numerical results and the available experiment data is carried out in the present study. The results of the different turbulence models were in a good agreement with the experimental results. The numerical results also concluded that the k-kl-ω turbulence model gave favorable results compared with the experiment. Design/methodology/approach It is very important to study the flow characteristics of detached flows. Therefore, the current study investigates numerically the flow characteristics in backward facing step by using two-, three- and seven-equation turbulence models in the finite volume code ANSYS Fluent. In addition, hybrid grid has been used to improve the capability of the unstructured mesh elements for predicting the flow separation in this case. Comparison between the different turbulence models and the available experimental data was done to find the most suitable turbulence model for simulating such cases of detached flows. Findings The present numerical simulations with the different turbulence models predicted efficiently the flow characteristics over the backward facing step. The transition k-kl-ω gave the best acceptable results compared with experimental data. This is a good concluded remark in the fields of fluid mechanics and hydrodynamics because the phenomenon of flow separation is not easy to be predicted numerically and can affect greatly on the predicted drag of moving bodies in many engineering applications. Originality/value The CFD results of using different turbulence models have been validated with the experimental work, and the results of k-kl-ω proven acceptable with flow characteristics. The results of the current study conclude that the use of k-kl-ω turbulence model will contribute towards a more efficient utilization in the fields of fluid mechanics and hydrodynamics.

scholarly journals Exactly solvable 1D model explains the low-energy vibrational level structure of protonated methane

2021 ◽  
Author(s):  
Jonathan Rawlinson ◽  
Csaba Fábri ◽  
Attila G. Császár
Keyword(s):  
Vibrational Level ◽  
Quantum Dynamics ◽  
Level Structure ◽  
Low Energy ◽  
Dimensional Model ◽  
One Dimensional ◽  
Effective Particle ◽  
Exactly Solvable ◽  
Vertex Graph ◽  
1D Model

A new one-dimensional model is proposed for the low-energy vibrational quantum dynamics of CH+5 based on the motion of an effective particle confined to a 60-vertex graph Γ60 with a...

Modeling Flash Diffusivity Experiments in Two Dimensions for Thick Samples

2008 ◽  
Author(s):  
Robert L. McMasters
Keyword(s):  
Experimental Data ◽  
Laser Flash ◽  
Two Dimensions ◽  
Flash Method ◽  
Two Dimensional ◽  
Dimensional Model ◽  
One Dimensional ◽  
Two Dimensional Model ◽  
Dimensional Analysis Method ◽  
Flash Diffusivity

The laser flash method for measuring thermal diffusivity is well established and has been in use for many years. Early analysis methods employed a simple model, in which one dimensional transient conduction was assumed, with insulated surfaces during the time subsequent to the flash. More recently, models of grater sophistication have been applied to flash diffusivity experiments. These models have been matched to experimental data using nonlinear regression and assume one-dimensional conduction. The advanced models have achieved highly accurate agreement with experimental data taken from thin samples, on the order of one millimeter in thickness. As samples become thicker, models which neglect edge losses can lose some conformity to the experimental data. The present research involves the application of a two dimensional model which allows for penetration of the laser flash into the sample. The accommodation of the flash penetration is important for porous materials, where the coarseness of the porosity is more than one percent of the sample thickness. Variability of the area of incidence of the flash is also investigated to determine the effect on the model and the results. Statistical methods are used in order to make a determination as to the validity of the two dimensional model, as compared with the one dimensional analysis method.

Transient Response in a One-Dimensional Model of Thermoelastic Contact

1996 ◽  
Vol 63 (3) ◽  
pp. 575-581 ◽  
Author(s):  
Z. S. Olesiak ◽  
Yu. A. Pyryev
Keyword(s):  
Boundary Conditions ◽  
Nonlinear Problem ◽  
Transient Response ◽  
Computational Simulation ◽  
Linear Equations ◽  
Numerical Results ◽  
System Of Equations ◽  
Dimensional Model ◽  
One Dimensional ◽  
Method Of Solution

We consider two layers of different materials with the initial gap between them in the field of temperature with imperfect boundary conditions in Barber’s sense. The model we discuss is that of two contacting rods (Barber and Zhang, 1988) which in the case of a single rod was devised and discussed by Dundurs and Comninou (1976, 1979). In this paper we try to make a step further in the investigation of the essentially nonlinear problem. Though we consider a system of the linear equations of thermoelasticity the nonlinearity is induced by the boundary conditions dependent on the solution. We present an algorithm for solving the system of equations based on Laplace’s transform technique. The method of solution can be used also in the dynamical problems with inertial terms taken into account. The numerical results have been obtained by a kind of computational simulation.

scholarly journals Floods effects on rivers morphological changes application to the Medjerda River in Tunisia

2016 ◽  
Vol 64 (1) ◽  
pp. 56-66 ◽  
Author(s):  
Mohamed Gharbi ◽  
Amel Soualmia ◽  
Denis Dartus ◽  
Lucien Masbernat
Keyword(s):  
Sediment Transport ◽  
Extreme Events ◽  
Morphological Changes ◽  
High Accuracy ◽  
Dimensional Model ◽  
One Dimensional ◽  
1D Model ◽  
Analysis Of Results ◽  
Major Floods ◽  
Natural Domains

Abstract In Tunisia especially in the Medjerda watershed the recurring of floods becoming more remarkable. In order to limit this risk, several studies were performed to examine the Medjerda hydrodynamic. The analysis of results showed that the recurrences of floods at the Medjerda watershed is strongly related to the sediment transport phenomena. Initially, a one dimensional modelling was conducted in order to determine the sediment transport rate, and to visualize the river morphological changes during major floods. In continuity of this work, we will consider a two-dimensional model for predicting the amounts of materials transported by the Medjerda River. The goal is to visualize the Medjerda behaviour during extreme events and morphological changes occurred following the passage of the spectacular flood of January 2003. As a conclusion for this study, a comparative analysis was performed between 1D and 2D models results. The objective of these comparisons is to visualize the benefits and limitations of tested models. The analysis of the results demonstrate that 2D model is able to calculate the flow variation, sediment transport rates, and river morphological changes during extreme events for complicated natural domains with high accuracy comparing with 1D Model.

scholarly journals Determining the minor loss coefficient of cone diffusers

2020 ◽  
Vol 207 ◽  
pp. 04004
Author(s):  
Gencho Popov ◽  
Kliment Klimentov ◽  
Boris Kostov ◽  
Reneta Dimitrova
Keyword(s):  
Experimental Data ◽  
Energy Efficiency ◽  
Data Base ◽  
Pipe Flow ◽  
Empirical Equation ◽  
Numerical Results ◽  
Loss Coefficient ◽  
Straight Pipe ◽  
Pipe Section ◽  
Ansys Cfx

This work represents results concerning different methods, used to determine the minor loss coefficient of a cone diffuser, installed at the system’s outlet. These results are compared with experimental data and numerical results, obtained after using ANSYS CFX and the data base of Pipe Flow Expert. For determining the minor loss coefficient of a cone diffuser, being installed at the system outlet and having a straight pipe section in front of it, some models in ANSYS CFX are established. These models are validated by using previously published experimental data. An empirical equation, based on the results found, enabling the accomplishment of analytical studies concerning the energy efficiency of fan systems, using an outlet diffuser, has been established.

scholarly journals Impact of a crushing ice particle onto a dry solid wall

2015 ◽  
Vol 471 (2183) ◽  
pp. 20150525 ◽  
Author(s):  
I. V. Roisman ◽  
C. Tropea
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Solid Wall ◽  
Rigid Wall ◽  
Ice Crystals ◽  
Particle Impact ◽  
Ice Crystal ◽  
Dimensional Model ◽  
One Dimensional ◽  
Theoretical Predictions

This is a theoretical study about ice particle impact onto a rigid wall. It is motivated by the need to model the process of ice crystal accretion or damage caused by an ice particle impacts. A quasi-one-dimensional model of ice particle impact and deformation is developed. Spherical, cylindrical and conical shapes of the ice crystals are analysed. The model is able to predict particle residual height, the force produced by impact and the collision duration. The theoretical predictions agree well with the available experimental data.

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