Development of Reverse Monte Carlo Ray Tracing to Solve Radiative Heat Transfer in Fibrous Materials

Speaker: Ahmed H. Yassin, University of Kentucky
June 8, 2023

Presentation

Abstract

Modeling of radiative heat transfer in ablative thermal protection systems (TPS) materials is challenging because of several factors such as heterogeneity and anisotropic nature of fiber-matrix structure of the material, the need to choose a computationally tractable method to solve the radiative transfer equation, and the need to accurately separate the solid and gas thermal conductivities from effective conductivity. To address these challenges, an in-house reverse Monte Carlo ray tracing (RMCRT) radiative heat transfer solver has been developed. Our RMCRT solver has lower statistical errors, reduced development time and computational cost, and includes the modeling of anisotropic and heterogenous media. The solver has also been coupled to a material response solver to account for in-depth radiative transfer inside TPS materials. The features of the RMCRT solver along with the coupling mechanics will be presented. Additionally, at the gas-solid interface, typically radiative heat flux is determined by using constant emissivity, considered to be an intrinsic material property. The RMCRT solver will be used to demonstrate that emissivity is not an intrinsic property. Rather, emissivity is an effective property of the medium (material) and it also depends on the temperature profile inside the material, not just the surface temperature. Obtaining emissivity requires information on the absorbed and reflected parts of emissions within the material, which in turn necessitates an accurate prediction of radiative transfer through the desired material.

Biography

Ahmed H. Yassin is a doctoral candidate within the Mechanical and Aerospace Engineering Department at the University of Kentucky, under the supervision of Prof. Savio Poovathingal. His research primarily focuses on radiative heat transfer within fibrous insulators, and the impact of radiative transfer on ablative heat shield materials. Ahmed holds an M.Sc. degree in Mechanical Engineering from Arab Academy for Science, Technology, and Maritime Transport. During his master’s research, he worked on optimization of blade profiles of horizontal axis wind turbines. Additionally, Ahmed has professional experience as an R&D engineer in the automotive industry, specifically in air conditioning and refrigeration. In this role, he successfully introduced new air conditioning units to the automotive market in Egypt.

Seminar Participation

Attending In Person

For select seminars, you may wish to attend in-person if you are in the vicinity of NASA Ames Research Center. These AMS seminars are held in Building N258 in Room 127, just off the front lobby. Sessions available to attend in-person will be indicated in the announcement information. In-person participants without NASA badges will need a valid visitor badge (US citizenship or permanent residency is required) to enter the facility.

Join Us Online

To attend an AMS seminar, click on the Microsoft Teams link in the seminar description. You can connect through the desktop Teams App if you have it, or you can select "Watch on the Web Instead" to enter the meeting as a guest. Please ensure that you've muted your microphone in Teams before you select "Join Now" to enter the meeting lobby.