Luiz Fernando Lopes Rodrigues Silva

Development and implementation of a polydispersed multiphase flow model in OpenFOAM

Abstract The two-phase flow solver implemented in the open-source OpenFOAM code was extended to a multiphase flow formulation ( n dispersed and one continuous phases) and then coupled to the population balance equation (PBE) solution by the Direct Quadrature Method of Moments (DQMOM), originating a polydispersed multiphase flow solver. Although each dispersed phase has its own velocity field, the present implementation considers only the interfacial momentum exchange between the continuous and the dispersed phases. The multiphase flow formulation was described and the details of the PBE–CFD coupling algorithms in OpenFOAM were provided. The implementation of the multiphase flow code was verified and evaluated against the original OpenFOAM two-phase flow solver for flow through a 2D backward facing step, using simplified breakage and aggregation kernels. The computational cost of both codes were compared for serial and parallel simulations.

Comparison of the accuracy and performance of quadrature-based methods for population balance problems with simultaneous breakage and aggregation

Simulations of polydisperse multiphase flows must include the effects of particle breakage and aggregation, which requires the solution of the population balance equation (PBE). Therefore, the analysis of the existing numerical techniques to solve the PBE regarding their efficiency and accuracy is paramount to their implementation in CFD codes. This work focused on analyzing the three quadrature-based methods available in the literature (QMOM, DQMOM and PPDC) in terms of efficiency and accuracy and against the classical method of classes. Analytical solutions were used to derive test cases from dominant breakage to dominant aggregation. The methods were evaluated in terms of moment accuracy and convergence. The computational costs were evaluated for all cases. It was verified that PPDC has poor convergence and is not adequate. For all cases, the QMOM and DQMOM solutions presented similar accuracy, but the DQMOM was the most efficient method.

Scaling laws for network model permeability: application to wellbore oil flow simulation with solid deposition

Network absolute permeability, evaluated by solving the Kirchhoffs equations for several network realizations, was correlated with some network parameters using scaling laws. Two kinds of site-bond network assembling algorithms were used to build networks with and without spatial correlation of their element size distributions. Simple models for solid deposition damage were applied to generate morphology-evolving processes for a given network. Simple functional forms were able to correlate the permeability for the two assembling algorithms and the damage processes. Such scaling laws allow the absolute permeability prediction from the network parameters, avoiding the time-consuming solution of the Kirchhoffs equations. This enables an efficient coupling of network models to flow simulation models for morphology-evolving problems. When this method was applied to a model for wellbore flow under asphaltene deposition, a speed up between 7 and 25 times was achieved.

Modeling and simulation of mixing in water-in-oil emulsion flow through a valve-like element using a population balance model

Abstract Emulsion flows are very common in natural processes as well as in several engineering areas, such as in the process of desalting crude oil that occurs in refineries. This kind of flow is described as a polydispersed multiphase flow. In this work, we evaluated the behavior of water-in-oil emulsion flowing through a duct with an element used to mimic the effect of a globe valve. An Eulerian multi-fluid approach was employed by solving the population balance equation coupled with computational fluid dynamics. Coalescence and breakage models recently developed were extended to this inhomogeneous model. A bivariate population balance problem was also solved to demonstrate the mixing caused by the valve-like element. The simulated results showed good agreement with the available experimental data for the Sauter and DeBroukere mean diameters.

Comparison of methods for multivariate moment inversion—Introducing the independent component analysis

Abstract Despite the advantages of the moment based methods in solving multivariate population balances models, these methods still suffer with the so-called multivariate moment inversion problem. Although univariate moment inversion is achieved without major problems this is not true for multivariate cases, for which there is no well established methodology. This work presents a comparative analysis of the existing methods regarding their accuracy and robustness. A new moment inversion method based on the independent component analysis was proposed and analyzed. Improvements in accuracy and robustness were achieved by combination of different moment inversion methods.

A moving mesh interface tracking method for simulation of liquidliquid systems

This manuscript presents a moving mesh interface tracking procedure, with a novel treatment for phase coupling. The new coupling strategy allows accurate predictions for the interface behaviour in a wide range of macroscopic properties with great potential to explore liquidliquid systems. In this approach, governing equations are applied to each phase individually while the interface is represented by a zero-thickness surface that contemplates inter-phase jumps. These equations are described in an arbitrary LagrangianEulerian finite volume framework. Computations consider the pressure-corrector PISO method. The new treatment for phase coupling incorporates the interfacial jump updates within the pressure/velocity calculations. Additionally, cell-centred values from both phases are considered when calculating convective and diffusive terms at the interface. The employment of GGI (Generalized Grid-Interface) interpolation provides conservative data mapping between surfaces for non-conformal meshes. The prediction capability of the new formulation is evaluated under different dominant effects governing interface motion. Simulated cases include gravity and capillary waves in a sloshing tank, three-dimensional drop oscillation for liquidliquid systems and drop deformation due to shear flow. The numerical results show good agreement with analytical transient profiles of interface position. The procedure is able to successfully represent systems with similar macroscopic properties, i.e. density and viscosity ratios approaching unity, and a broad range of interfacial tensions. Novel inter-phase coupling scheme for liquidliquid interface representation.Conservative data mapping capability for non-conformal meshes.Accurate description of motion/deformation under different driving forces.Evaluation of wide range of interfacial tensions, density and viscosity ratios.