Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
NUMERICAL SIMULATION OF THE RESTART PROBLEM FOR THIXOTROPIC FLUIDS
Submission Author:
Monica Naccache , RJ , Brazil
Co-Authors:
Leandro Alencar
Presenter: Monica Naccache
doi://10.26678/ABCM.ENCIT2016.CIT2016-0184
Abstract
Many industrial applications involve the transport of complex fluids, such as paint, paper and oil. Especially for the oil production in ultra-deep water fields, the transport of oil with high paraffins content can create some difficulties. The produced fluid cools down inside the pipeline when the production stops and the paraffin crystals form an interlocking gel-like structure. The knowledge of the tixotropic behaviour of the produced fluid together with the simulation capacity to solve the restart phenomenon enables the economical design of pumps and lines with reasonable precision and size to break the gel. Several mathematical models exist in the literature that tries to explain this phenomenon, including scalar models in which the structure of the fluid is represented by one single parameter. This type of model is simple and with the most practical use. So it was chosen for this thesis. A non-linear first order differential equation is used for the thixotropic evolution relation and must be coupled with the standard transport equations. The use of a numerical simulator that can solve this problem gives the engineer the tool required to solve for any geometry the restart problem. The issue lies within the simulator capacity to represent the thixotropic behaviour and if it has the confiability required for industrial applications. In this thesis the algorithm developed to implement the thixotropic simulation within the CFD commercial tool Fluent© is presented for a purely viscous incompressible fluid. Two restart cases are discussed in detail and the effect of the inlet boundary condition is presented together with a relationship between the restart time and the inlet pressure for different thixotropic conditions. A comparison between the simulation of the restart problem and some experimental data shows that the expected behaviour is achieved with good qualitative similarities. In conclusion, the results herein presented prove the potential use of CFD with thixotropic fluids enabling the optimized design of production systems.
Keywords
CFD, Thixotropy, Non-Newtonian flow, Restart Problem, CFD, Thixotropy, Non-Newtonian flow, Restart Problem, CFD, Thixotropy, Non-Newtonian flow, Restart Problem
