Project Title: "Numerical simulations of the flow of Newtonian and non-Newtonian fluids through a continuous ohmic heater"
Author: Hortensia Delgado Solís, Universidad de Costa Rica, Costa Rica
Host Supervisor: Prof. António Vicente, University of Minho, Portugal
Keywords: Newtonian Fluids, Non-Newtonian Fluids, Ohmic Heater, study, RTD’s
Newtonian and non-Newtonian Fluids were simulated in a pilot ohmic heater to make a study of the behaviour of different kinds of fluids when they are exposed to conductive heating.
The simulations were made for several inlet mass flow rates and different operational temperatures depending on the specific characteristics of each fluid.
The simulations were made using FluentTM software and the mesh that describes the interior of the ohmic heater was built with GambitTM software. A 2D mesh with 29040 cells and a 3D mesh with 378348 cells were created. For simplicity, the first simulations where run using water but the work has proceeded using milk (as an example of a Newtonian fluid) and strawberry pulp (as an example of a non-Newtonian Fluid).
For all the conditions tested the fluid phase is described using the laminar flow model; however, in those cases when convergence was not achieved the Spalart-Allmaras model was used instead.
Once the convergence was achieved a study of the mesh independency became necessary. The mesh independency was analyzed using the Residence Time Distribution (RTD), which describes the mean time that a fluid element spends inside the system (the ohmic heater). For such analysis, a study of the energy that the different numbers of cells generate was also performed as a fundamental aspect to evaluate the mesh independency and guarantee that the mesh used is the one that optimizes the simulation process.
