Simulations of intermittent two-phase flows in pipes using smoothed particle hydrodynamics

Abstract

Slug flows are a typical intermittent two-phase flow pattern that can occur in submarine pipelines connecting the wells to the production facility and that is known to cause undesired consequences. In this context, computational fluid dynamics appears to be the tool of choice to understand their formation. However, few direct numerical simulations of slug flows are available in the literature, especially using meshless methods which are known to be capable of handling complex problems involving interfaces.In this work, a 2D study of the instability processes leading to the formation of intermittent flows in pipes is conducted using an existing multiphase smoothed particle hydrodynamics formulation associated with inlet and outlet boundary conditions. This paper aims to demonstrate the applicability of smoothed particle hydrodynamics to a given set of close-to-industry cases.First, we check the ability of our implementation to reproduce flow regimes predicted by Taitel and Duckler's flow map. Then, we focus on the transition processes from one flow pattern to the other. Finally, we present the results obtained for more realistic cases with high density and viscosity ratios.

Comparison of multiphase SPH and LBM approaches for the simulation of intermittent flows

“…It means that the average pressure along the pipe's height is higher at the outlet than at the inlet. This phenomenon was already seen in [16] and may be due to several factors : the quality of the boundary conditions, the recirculation areas at the entry that tend to lower the pressure and the averaging area chosen (i.e. 0.1 m (from the inlet) ×D).…”

“…In this section, we will describe in details the SPH immisible multiphase model used in this work. This formulation and the associated open boundary conditions are taken from [42,16].…”

“…The SPH formulation adopted for this paper is identical to the one used in [16]. We will not here recall in detail the SPH discretization process and will assume that the reader already has experience with SPH.…”

“…For inlet/outlet BC, the method extensively described in [16] (combining ideas from [95,96]) has been used. The inlet and outlet boundaries are extended with a buffer layer of size κh to ensure a full kernel support.…”

“…A detailed comparison of both codes [9] concludes that although performing equally well on simple cases, they have trouble to simulate complex cases with a dominant gas phase. From an academic perspective, different models and methods have been used for slug flow modeling, for example volume-of-fluid [10,11], level-set [12,13], lattice Boltzmann method (LBM) [14], smoothed particle hydrodynamics (SPH) [15,16] or phase field [17,18], but these are applied on microfluidic problems for the most part. In this work, we will focus on two of them : SPH and LBM, because while they are very different numerical methods, both in their origin and in their nature, they have shown a strong potential to model multiphase flows [19,20,21].…”