The Accuracy and Efficiency of Viscosity Models for High Temperature Gas: Applications to a Charring Ablation

When engineering a vehicle for an atmospheric reentry, any uncertainty poses a significant risk to the mission. In an attempt to avoid this risk, engineers tend to over-design, resulting in significantly increased cost. One cause of such uncertainty is the inaccuracy of the transport properties calculations. My proposed research will attempt to reduce this uncertainty by studying the viscosity of an 11-species gas model during the extreme conditions caused by a vehicle reentry. There are three modeling methods that I will be specifically focusing on: the Wilke mixing rule, the Gupta mixing rule, and the Boltzmann Sonine polynomial expansion method. I will be modeling these three methods under conditions of 200K to 20,000K for an 11-species model and determining under what conditions the three methods are accurate. In addition to calculating their accuracy, I will also be determining the efficiency of each model. By examining the efficiency, I will be able to write an algorithm that will, at any temperature up to 20,000K, select and compute the most efficient method for calculating the viscosity while still retaining a high level of accuracy. This algorithm will then be applied to a larger material response code for charring ablation. If successful, my proposed research will increase the confidence and efficiency of viscosity calculations, giving engineers more specific design parameters.