The main objective of this study is to fundamentally investigate the flow physics and the relationship to heat transfer in the presence of roughened surfaces undergoing jet impingement cooling mechanisms in a confined channel. Thermal and fluid dynamics characteristics are directly related to the surface condition. The surface roughness is proven to play a significant role in the surface heat transfer and skin friction coefficient. In combination with the surface finish, the flow condition plays a particular role in the turbulence behavior near the wall. The magnitude of these engineering quantities tends to deviate from a smooth surface compared to a rough surface scenario. The development of accurate lower and high-fidelity models is essential in the engineering world. Predicting the heat transfer and fluid mechanics behavior inside a component is essential for a designer, such as improving wall functions within the CFD community. Usually, literature only includes well-defined rough surfaces driven by some geometric parameters, non-uniform and irregular surfaces like the one found in additive manufacturing and other physics forming phenomena is somewhat lacking. The basic geometric configuration of a single jet impingement was chosen due to the ability to create a wall jet from a stagnation region. The experimental facility was designed under no crossflow configuration, where fluid enters from the plenum passing through the orifice hole (jet) and exiting in the radial direction of a confined channel. The current research investigated the fluid dynamics associated with jet impingement over rough surfaces using non-intrusive experimental methods. Multiple jet Reynolds numbers were investigated, ranging from 21,000 to 110,000 for three different jet diameter to roughness ratios. The current research study investigated heat transfer and fluid behavior using non-intrusive experimental methods. Temperature-sensitive paint (TSP) was utilized to obtain scalar temperature field over smooth and rough surfaces. These experimental results will be compared with available literature. The flow physics was investigated by performing stereoscopic Particle Image Velocimetry. The velocity fields were further analyzed using Proper Orthogonal Decomposition (POD) and tested versus the wall similarity theory. High accuracy microphones were utilized to obtain unsteady pressure values at different rough surfaces.


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Graduation Date





Kapat, Jayanta


Doctor of Philosophy (Ph.D.)


College of Engineering and Computer Science


Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering




CFE0008814; DP0026093





Release Date

December 2026

Length of Campus-only Access

5 years

Access Status

Doctoral Dissertation (Campus-only Access)

Restricted to the UCF community until December 2026; it will then be open access.