Our team at MFIP2017

A simplified, mono-dimensional two-fluid model with artificial diffusion for slug capturing

Arianna Bonzanini, Davide Picchi, Pietro Poesio: A simplified, mono-dimensional two-fluid model with artificial diffusion for slug capturing. 14th International Conference on Multiphase Flow in Industrial Plants, Desenzano del Garda, Italy, 13-15 September, 2017, ISBN: 978-88-88198-40-8.

Bonzanini_MFIP2017

Abstract

In this work we propose a numerical resolution of a 1D, transient, simplified two-fluid model regularized with artificial diffusion to model stratified, wavy, and slug flow in horizontal and slightly inclined pipes. The artificial diffusivity is used to avoid the growth of instabilities at short wavelengths. A method to set the artificial diffusion values case by case (depending on the pipe geometry and on the liquid and gas flow rates) was
developed to obtain the desired cut-off, basing the choice on the linear stability analysis. To describe slug formation and growth, we develop a proper criterion to simulate two-phase to single phase flow transition, to deal with the issue of liquid volume fraction approaching unity. It will be shown, by comparison with well-known empirical relations and experimental data, that the developed code computes slug velocity, frequency and length distribution in a fairly accurate way. The numerical code can predict flow pattern transition, discerning between stratified smooth, stratified wavy, and slug flow.

BibTex

BibTeX (Download)

@conference{Bonzanini_MFIP2017,
title = {A simplified, mono-dimensional two-fluid model with artificial diffusion for slug capturing},
author = {Arianna Bonzanini and Davide Picchi and Pietro Poesio},
isbn = {978-88-88198-40-8},
year  = {2017},
date = {2017-09-13},
address = {Desenzano del Garda, Italy, 13-15 September},
organization = {14th International Conference on Multiphase Flow in Industrial Plants,},
abstract = {In this work we propose a numerical resolution of a 1D, transient, simplified two-fluid model regularized with artificial diffusion to model stratified, wavy, and slug flow in horizontal and slightly inclined pipes. The artificial diffusivity is used to avoid the growth of instabilities at short wavelengths. A method to set the artificial diffusion values case by case (depending on the pipe geometry and on the liquid and gas flow rates) was
developed to obtain the desired cut-off, basing the choice on the linear stability analysis. To describe slug formation and growth, we develop a proper criterion to simulate two-phase to single phase flow transition, to deal with the issue of liquid volume fraction approaching unity. It will be shown, by comparison with well-known empirical relations and experimental data, that the developed code computes slug velocity, frequency and length distribution in a fairly accurate way. The numerical code can predict flow pattern transition, discerning between stratified smooth, stratified wavy, and slug flow.},
keywords = {artificial diffusion, Numerical simulation, Oil&Gas, Slug flow, Two-fluid model regularization},
pubstate = {published},
tppubtype = {conference}
}


A slug capturing method in unconventional scenarios: the 5ESCARGOTS code applied to non-Newtonian fluids, high viscous oils and complex geometries

Marco Ferrari, Arianna Bonzanini, Pietro Poesio: A slug capturing method in unconventional scenarios: the 5ESCARGOTS code applied to non-Newtonian fluids, high viscous oils and complex geometries. 14th International Conference on Multiphase Flow in Industrial Plants, Desenzano del Garda, Italy, 13-15 September, 2017, ISBN: 978-88-88198-40-8.


Ferrari_MFIP2017

Abstract

Previous works showed that a one-dimensional, hyperbolic, transient five-equation two-fluid model can predict automatically the formation, growth, and subsequent development of slugs in horizontal and near horizontal flow. This method was implemented in a finite volume numerical scheme – called 5ESCARGOTS code. Comparison with experimental data showed that it can be used to predict the flow pattern and statistical characteristics (slug velocity, length, and frequency). However, the capabilities of this approach have been tested only for water-air flows in a straight horizontal pipe.
In this work, we validate the application of the code to some unconventional problems. Firstly, we test the possibility of slug capturing approach to describe and predict the relevant features of air/high viscosity oils or air/non-Newtonian fluids flows. Comparisons between some slug characteristics and empirical correlations, available in literature, are discussed. Then, we move from simple geometries toward more complex conditions that may be representative of actual application cases, also employing high viscous oils as liquid phase. Comparison against experimental data shows results in reasonable agreement.

BibTex

BibTeX (Download)

@conference{Ferrari_MFIP2017,
title = {A slug capturing method in unconventional scenarios: the 5ESCARGOTS code applied to non-Newtonian fluids, high viscous oils and complex geometries},
author = {Marco Ferrari and Arianna Bonzanini and Pietro Poesio},
isbn = {978-88-88198-40-8},
year  = {2017},
date = {2017-09-13},
address = {Desenzano del Garda, Italy, 13-15 September},
organization = {14th International Conference on Multiphase Flow in Industrial Plants,},
abstract = {Previous works showed that a one-dimensional, hyperbolic, transient five-equation two-fluid model can predict automatically the formation, growth, and subsequent development of slugs in horizontal and near horizontal flow. This method was implemented in a finite volume numerical scheme – called 5ESCARGOTS code. Comparison with experimental data showed that it can be used to predict the flow pattern and statistical characteristics (slug velocity, length, and frequency). However, the capabilities of this approach have been tested only for water-air flows in a straight horizontal pipe.
In this work, we validate the application of the code to some unconventional problems. Firstly, we test the possibility of slug capturing approach to describe and predict the relevant features of air/high viscosity oils or air/non-Newtonian fluids flows. Comparisons between some slug characteristics and empirical correlations, available in literature, are discussed. Then, we move from simple geometries toward more complex conditions that may be representative of actual application cases, also employing high viscous oils as liquid phase. Comparison against experimental data shows results in reasonable agreement. },
keywords = {Highly viscous oil, Non-Newtonian liquid, Numerical simulation, pipeline, slug capturing, Two-fluid model},
pubstate = {published},
tppubtype = {conference}
}


The development of air/high viscosity oil slug flow in horizontal small diameter pipes

Gianluca Losi, Pietro Poesio: The development of air/high viscosity oil slug flow in horizontal small diameter pipes. 14th International Conference on Multiphase Flow in Industrial Plants, Desenzano del Garda, Italy, 13-15 September, 2017, ISBN: 978-88-88198-40-8.


Losi_MFIP2017

Abstract

The development of slug flow structure is a crucial topic when dealing with the design of pipelines and their processing system. Thus, many efforts have been done to model air/water slug flow and its true unsteady nature. Instead, the aim of this work is to investigate the evolution of gas/high viscosity oil slug flow experimentally and with numerical simulations. Experiments are carried out in a 9 m horizontal test loop with an internal diameter of 22 mm. The slug and bubble lengths are measured with six capacitance probes placed at different distances from the inlet. An algorithm was designed to analyse the signals and build the probability density functions of the lengths along the pipe. From their comparison, the role of viscosity in the evolution of slug flow is studied. The main effect is the increase of the pressure drops that causes an acceleration of gas bubbles and their expansion along the pipe. A simple slug tracking model is used to calculate the length distributions along the system and the results are compared with the experimental data.

BibTex

BibTeX (Download)

@conference{Losi_MFIP2017,
title = {The development of air/high viscosity oil slug flow in horizontal small diameter pipes},
author = {Gianluca Losi and Pietro Poesio},
isbn = {978-88-88198-40-8},
year  = {2017},
date = {2017-09-14},
address = {Desenzano del Garda, Italy, 13-15 September},
organization = {14th International Conference on Multiphase Flow in Industrial Plants,},
abstract = {The development of slug flow structure is a crucial topic when dealing with the design of pipelines and their processing system. Thus, many efforts have been done to model air/water slug flow and its true unsteady nature. Instead, the aim of this work is to investigate the evolution of gas/high viscosity oil slug flow experimentally and with numerical simulations. Experiments are carried out in a 9 m horizontal test loop with an internal diameter of 22 mm. The slug and bubble lengths are measured with six capacitance probes placed at different distances from the inlet. An algorithm was designed to analyse the signals and build the probability density functions of the lengths along the pipe. From their comparison, the role of viscosity in the evolution of slug flow is studied. The main effect is the increase of the pressure drops that causes an acceleration of gas bubbles and their expansion along the pipe. A simple slug tracking model is used to calculate the length distributions along the system and the results are compared with the experimental data.},
keywords = {Air–oil flow, gas bubble, Highly viscous oil, Slug flow, small diameter pipe},
pubstate = {published},
tppubtype = {conference}
}