Award Date


Degree Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Committee Member

Yitung Chen

Number of Pages



This thesis deals with the numerical simulation of the thermal comfort and contaminant transport of an under floor air distribution (UFAD) system. Within the last few years, UFAD systems have become popular design alternative to conventional distribution (CAD) such as overhead distribution systems for thermal and ventilation control. Recent advances in computational fluid dynamics (CFD) and computer power make it possible to accurately predict some features of airflow within ventilated spaces. The CFD method has been successfully applied for airflow analysis in relatively complicated conditions, such as non-isothermal, three-dimensional and with furniture inside the room. The goal of this research project is to analyze the thermal comfort of UFAD systems and help to reduce the design cycle through the development of mathematical and computational models; In this project, the thermal comfort of occupants in 2D and 3D steady-state model of a room has been analyzed. The flow characteristics such as velocity, temperature, relative humidity and species concentration for both the models have been calculated and studied. Initially, the computational mesh for both 2D and 3D models have been generated using GAMBIT and the general purpose CFD code FLUENTRTM6.2 has been used as a numerical solver for the present 2D and 3D simulation. The pre-processing and post-processing have been done using FLUENT. A non-staggered grid storage scheme is adopted to define the discrete control volumes. The solver used is a segregated solver which is a solution algorithm with which the governing equations are solved sequentially. The Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm is used to resolve the coupling between pressure and velocity. An implicit technique is used to linearize the discrete and non-linear governing equations. The discretization method used by the FLUENT RTM is finite volume method (FVM) in which the space is divided into a finite number of control volumes and solves the partial differential equations; From the numerical study of the 2D office cubicle setting, results show that the relative humidity, temperature, velocity and species concentration profiles have good agreement with the ASHRAE standards. The UFAD system of BTLab and living room, is numerically studied and it can be observed that the flow is well mixed and distributed uniformly due to the swirl diffusers. The flow contours such as velocity, temperature, relative humidity and species concentration have been analyzed and parameters such as PMV (Predicted Mean Vote) and CRE (Contaminant Removal Effectiveness) have been calculated and are found to be in the comfort zone on the thermal sensation scale. This shows that the obtained results from the numerical study are reasonable.


Comfort; Contaminant; Numerical; Rooms; Simulation; System; Thermal; Transport; UFAD

Controlled Subject

Mechanical engineering

File Format


File Size

2437.12 KB

Degree Grantor

University of Nevada, Las Vegas




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