Computational environmental hydraulics buoyant convection

• Main Author: Ooi, Hui Min
• Other Authors: Law Wing-Keung, Adrian
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/60045
• Institution: Nanyang Technological University

Thermals are isolated releases of buoyant miscible fluid that propagate vertically. A single thermal is instantaneously formed when a volume of positive or negative buoyant fluid is released into a quiescent ambience. The rate at which thermals spread under different conditions is currently inconsistent and vary across different literatures. Using Computational Fluid Dynamics (CFD) modeling, the spreading rate can be analysed in details. Past studies had been conducted using two-dimensional (2D) mesh models and by solving the Reynolds-averaged Navier-Stokes equations with a two-equation turbulence closure. Not much research has been done using the large eddy simulation (LES) model. The present study is motivated by Zhao et al. (2013)'s work on measuring the internal flow and density distributions based on the ensemble-average of large number of experiments. It is aimed to simulate the development of a three-dimensional miscible thermal using Large Eddy Simulation (LES), and explore the possibility of buoyant vortex breakdown. LES model is expected to produce more flow details than RANS model as it is able to capture the transient characteristics of turbulent flow. The results will be compared with the experimental data (Zhao et al., 2013) and simulation results based on RANS model (Lai et al., 2013).