Multiphase flows

Multiphase flows have been studied over the years. The study focuses mainly on two phase flow in slug regime. It began by studying phenomena/isolated parts of the flow:

• The wake of ascending slug bubbles in vertical macro columns containing a stagnant Newtonian liquid;
• The flow around slug bubbles, nose and film, rising in vertical macro columns containing a stagnant Newtonian liquid;
• The coalescence of ascending slug bubbles in vertical macro columns containing a stagnant Newtonian liquid;
• The three previous steps were repeated with slug bubbles ascending in co-current with liquid for different flow rates;
• Experimental studies (PIV – image acquisition for further processing) were carried out with gas and liquid in co-current flow

After these experimental steps, we proceeded to the numerical simulation, fed by the conclusions of the experimental work. Briefly:

• Simulation of a continuous gas-liquid flow with slug wake and liquid in laminar regime;
• Simulation of a continuous gas-liquid flow with slug wake and liquid in turbulent regime;
• Simulation of a continuous flow gas-liquid with slug wake in transition regime and liquid in laminar regime.

With these simulations, it was possible to predict gas-liquid flow characteristics in several situations, both from the point of view of the physical properties of the fluids and also from the geometry of the column. These studies were later extended to other types of fluids and scales:

• Non-Newtonian fluids, with and without elastic properties;
• Flows of two immiscible liquids (Taylor drops);
• Flows in mini and micro channels.
• Mass transfer from a bubble to the flowing liquid at the macro scale and also at the micro scale.

In recent years, research has focused on the transport of oil from deep wells, the so-called pre-salt region. This research has been in collaboration with Prof. Attila Freire of the Federal University of Rio de Janeiro responsible for the LabMultiFasico of UFRJ. Several joint projects were submitted (research group-CEFT and UFRJ), two of which were approved by Galp-Brasil. One of objectives is, based on the knowledge acquired, to develop a numerical code that can predict the flow of the oil (oil + air + water) in the extraction from the pre-salt wells.

Recently two others topics start to be studied:

• CFD advanced modelling combined with 3D printing manufacture for process intensification involving multiphase flow, heat/mass transfer and reaction with the goal of transferring know how to private companies. This topic has been developed in the framework of a European project led by SINTEF- Noruega
• Development of droplet microfluidics and microjets to produce new particles and smart fluids and to develop new 3D printing techniques.