Departamento de Ingeniería Mecánica
Facultad de Ingeniería de la Universidad de Concepción

2015 Fondap 15130015

Prof. Pablo Cornejo (Investigador Asociado)
Centro de Recursos Hídricos para la Agricultura y Minería (CRHIAM)

A novel approach to assess the hydrodynamic effects of a salmon farm in a Patagonian channel: Coupling between regional ocean modeling and high resolution les simulation (2018), The interaction between local hydrodynamics conditions and salmon cages are important in disease transmission and in the transport of waste products generated by aquaculture. We propose a modeling methodology to assess the hydrodynamic effects of a salmon farm in a Patagonian channel. The method is based on the coupling between a Coastal and Regional Ocean COmmunity model (CROCO) and a high resolution Large Eddy Simulation (LES) model. A salmon farm located in the Estero Elefantes Channel (45°39′16.50″S–73°35′59.40″W) was used as a study case. The physical coherence of the results was validated by comparison with field current velocities measured with an Acoustic Doppler Current Profiler (ADCP). The model predictions were capable of reproducing the tendencies of the variation although there were some differences in magnitude. The results showed that the hydrodynamics of the Estero Elefantes Channel is dominated by two circulation modes depending on the current direction in the adjacent Moraleda channel. Both circulation modes are characterized by a highly unstable shear flow composed by turbulent structures that interact with the salmon cages. Therefore it is not possible to select a local control volume with arbitrarily defined inlets, outlets and impermeable walls to evaluate hydrodynamic processes relevant to the salmon farms. The presence of the cages modifies the natural hydrodynamics of the channel, attenuating the intensity of the local velocity magnitude and generating recirculation and retention zones near them. However, their effect is not confined locally because the perturbations introduced by the presence of cages are propagated far from them. The transport of material discharged inside the cages was also analyzed. This information should prove useful both for producers and the aquaculture management authority. https://doi.org/10.1016/j.aquaculture.2018.05.003

Co-firing of coal/biomass blends in a pilot plant facility: A comparative study between Opuntia ficus-indica and Pinus radiata. (2018), Chile has begun to promote the use of biomass to replace a fraction of the energy produced from coal. However, the power plants are located in the world driest desert, the Atacama Desert, and far from the forest resources. Fortunately, a cactaceous species named Opuntia ficus-indica, has proven to be able to grow under climate desert conditions. In this study the behavior of Opuntia ficus-indica under co-firing conditions with coal, is evaluated and compared to that of Pinus radiata, in terms of heat transfer, ash deposits formation and pollutant emissions in a 150 kW fluidized bed pilot plant. The results revealed a variation of the temperature profile inside the reactor, as well as a relationship between the efficacy factor and the base-acid ratio. The heat transfer coefficients in the dense bed evidenced a decrease in the heat transfers mechanisms attributed to a variation of the mean particle diameter and a greater presence of fuel particles. Under coal-Pine co-firing conditions, an increase in NO formation and a decrease of PM and SO2 concentrations was observed. While co-firing coal with Opuntia showed an increase in the particulate matter and a reduction of NO and SO2 concentrations. https://doi.org/10.1016/j.energy.2017.10.053

Transition from spray to roping in hydrocyclones. (2018), Although roping in hydrocyclones is a problem that has been studied by many researchers, we do not yet have a theory that relates all the variables involved. Several experimental works with different approaches such as mechanical energy balance, work on hydrocyclones with water only and hydrocyclone air core measurements with different instruments in the laboratory and plant have attempted to explain the roping phenomenon. They have addressed design variables such as apex to vortex diameters and different cone angles as well as operating variables such as inlet solid concentration, particle size, pressure and overflow and underflow flow rates and concentrations in order to understand their effect on the roping condition. In this paper we intend to verify some of the conclusions of these studies and establish inlet pressure and particle diameter as the variables that, in combination, lead from spray to roping. We present a computational model using Computational Fluid Dynamics (CFD) to study a 75-mm laboratory hydrocyclone operating at a variable flow rate and with three different particle diameters. The Reynolds Stress Model and Eulerian multiphase model were used to model the turbulence and interaction of phases, respectively. The solid particles are described with the kinetic theory of granular flows (KTGF). Physical coherence and accuracy were compared with experimental data, where errors are within the expected range for an engineering prediction. The results indicate that transition from spray to roping generates an increase in the inlet flow pressure and/or particle diameter at a constant solid concentration in the feed flow. For 20-µm-diameter particles an increase results in a decrease in the discharge angle, although it always has a spray shape, for 34-µm diameters increasing the inlet pressure generates a semi-rope discharge and for 70-µm-diameter particles a small increase in the inlet pressure generates a roping condition. Transition to roping is characterized by a decrease in the air core diameter and discharge angle due to slow rotational velocity when particle diameter increases or higher accumulation of the solid fraction in the apex when inlet pressure increases. The passage from spray to roping occurs with a change in the frequency spectrum of the pressure oscillations in the walls of the hydrocyclone, with high amplitudes at low frequencies for spray discharge and noisy signals in all spectrums and damped low frequencies for roping. https://doi.org/10.1016/j.mineng.2018.04.008

Evaluating the longitudinal stability of an UAV using a CFD-6DOF model (2015), Aerospace Science and Technology, en prensa

Numerical Studies on the Hydrodynamic Effect of a Salmon Farm in an Idealized Environment (2014), Aquaculture 430, 195-206, 2014

Mathematical Modeling of Coal Gasification in a Fluidized Bed Reactor Using Eulerian Granular Description (2011), International Journal of Chemical Reactor Engineering, vol. 11, 2011, Article A2

Submesoscale processes in upper ocean fronts: a numerical study using a Reynolds Stress Turbulence Model. Cornejo P.. Laboratorie de Physique des Océans. IFREMER-UBO. Brest, France. 2014

Simulación numérica de la formación de NOx en un quemador de gas natural. Romero P., Cornejo P., Farías O., Gallardo C.. XIII Jornadas de Mecánica Computacional, Universidad de Talca. Curicó, Chile. 2014

Estudio del efecto de la inclusión de biomasa en la combustión de carbón pulverizado. Pérez R., Cornejo P., Flores M., Gordon A., García X.. XIII Jornadas de Mecánica Computacional, Universidad de Talca. Curicó, Chile. 2014

Dinámica de fluidos geofísicos através de dinámica de fluidos computacional. Cornejo P.. ESSS conference and ANSYS users meeting. Santiago, Chile. 2014

Numerical simulation of an upper ocean front using a Reynolds Stress Turbulence Model. Cornejo P.. 11th World Congress on Computational Mechanics. Barcelona, Spain. 2014

Modelo multifase con fase no-newtoniana para la simulación de la dinámica de relaves mineros. Montero J., Cornejo P.. XIII Jornadas de Mecánica Computacional, Universidad de Talca. Curicó, Chile. 2014

Modelación CFD de aire seco en régimen hipersónico. Pino C., Cornejo P.. XIII Jornadas de Mecánica Computacional, Universidad de Talca. Curicó, Chile. 2014

Simulación numérica del efecto hidrodinámico de una jaula de cultivo de salmones en un ambiente idealizado. Cornejo P., Carrillo T., Sepúlveda H., Gutiérrez M., Olivares G.. XII Jornadas de Mecánica Computacional, Universidad de Santiago. Santiago, Chile. 2013

Evaluación de las características aerodinámicas de un cohete sonda en régimen de flujo compresible. Terán J.P., Cornejo P., Tinapp F.. XII Jornadas de Mecánica Computacional, Universidad de Santiago. Santiago, Chile. 2013

Evaluación de la estabilidad longitudinal de un trainer UAV mediante un modelo CFD-6DOF. Sandoval P., Cornejo P., Tinapp F.. XII Jornadas de Mecánica Computacional, Universidad de Santiago. Santiago, Chile. 2013

Biomass replacing in a pulverized coal utility boiler: predictions of performance and pollulant emissions using CFD tools. Cornejo P., Pérez R., Flores M., García X.. International conference on coal science and technology, The Pennsylvania State University. 2013

Simulación numérica de jaulas de cultivo y su efecto sobre la hidrodinámica local. Cornejo P.. I-Mar, Universidad de Los Lagos. Puerto Montt, Chile. 2012

Hidrodinámica de jaulas de cultivo de salmones mediante dinámica de fluidos computacional (CFD). Cornejo P.. Seminarios de geofísica. Departamento de Geofísica, Universidad de Concepción. Concepción, Chile. 2012

Simulación hidrodinámica del efecto de una jaula de cultivo bajo flujos idealizados. Cornejo P., Sepúlveda A., Gutierrez M. H.. IV Congreso Nacional de Acuicultura. 2012

Simulación numérica de la combustión de carbón pulverizado en un lecho arrastrado. P. Cornerjo, C. Rodríguez, O. Farías. VII Jornadas de Mecánica Computacional. Santiago. 2008