Banca de DEFESA: Luís Henrique Fraga Castro

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Luís Henrique Fraga Castro
DATE: 03/05/2023
TIME: 14:00
LOCAL: Plataforma Microsoft Teams
TITLE:

NUMERICAL STUDY OF MAGNETIC THERMAL CONVECTION IN A CAVITY

KEY WORDS:

Natural convection in cavities; magnetic natural convection; ferrofluid flow; heat transfer; numerical methods

PAGES: 77
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

This work presents a study on thermo-sensitive ferrofluid flow inside a two-dimensional cavity with insulated vertical walls and constant-temperature horizontal walls. The aim is to understand the influence of an external magnetic field and the impact of a rectangular obstacle inside the cavity on the flow field and heat transfer. The flow is assumed incompressible and laminar, and the ferrofluid is superparamagnetic, with susceptibility varying as a function of the temperature. The external magnetic field is generated by the electric current passing through a conducting wire, near the cavity. The set of governing equations comprises mass conservation, linear momentum, and energy equations. The problem is solved numerically using a finite differences method in a regular mesh. The pressure–velocity coupling and time evolution are carried out by a second-order projection method. When the wire is placed in the middle of the right insulated wall, the results show an increase in the average Nusselt with the magnetic field intensity. In addition, one observes that the wire position dramatically influences the flow topology, with significant variations in the average Nusselt number. A study on the effects of the presence of an obstacle inside a cavity was conducted. Two cases were considered: one where the obstacle is thermally insulated and another where the temperature is kept constant. The results reveal that the presence of the obstacle changes the way the magnetic field modifies the flow, such that the position that maximizes the Nusselt number varies considerably between the situations with and without the obstacle. It was observed that the presence of this object, depending on the thermal boundary conditions, can induce the formation of flow structures similar to Bénard cells. Motivated by this observation, a preliminary study on the effect of the magnetic field on a natural convection flow in the Bénard cell regime was conducted. It was shown that the presence of the magnetic field can alter the number of these cells and increase the average Nusselt number of the flow by more than 50%.

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