DSMC Analysis of Fractal-like Aggregates of Spores in the Semi-rarefied Flow Regime
Open Access
Author:
Zhu, Tong
Graduate Program:
Aerospace Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
Deborah A Levin, Thesis Advisor/Co-Advisor Michael Matthew Micci, Thesis Advisor/Co-Advisor George A Lesieutre, Thesis Advisor/Co-Advisor
Keywords:
DSMC heat transfer fractal
Abstract:
The work presented in this paper is a continuation of our efforts to develop a realistic bio-engineering model for predicting the survivability of anthrax spores subjected to high temperature gas environment. One of the major mechanisms of deactivating spores is to expose them to elevated temperatures and careful, exposure-tube experiments have been carried out to ascertain the deactivation mechanism. Spores typically exist in nature as aggregates, but, simulating the heat transfer to clumps of spores is difficult because of the highly irregular geometry of spore clumps. In this work we implement the tunable particle-cluster and cluster-cluster algorithms to generate fractal-like spore aggregates. We compare the algorithm output as a function of algorithm parameter input with a typical spore clump image. Since the spore aggregate size is small and is on the order of the mean free path even at atmospheric conditions, we use the direct simulation Monte Carlo method to model the heat transfer to each of the spores in the aggregate. We study the shielding effect of aggregate spores on a single spore in the clump, finding that for aggregates on the order of 100 that the shielding effect is about 25% ~ 45% compared to a single, isolated spore.
