|Acquisition Program: || Objective: ||This topic will develop mathematical modeling of release mechanisms of fine particles from indoor surfaces under typical building heating, ventilating and air conditioning (HVAC) operation. The project will investigate resuspension mechanisms of fine particles from indoor surface, identify physical and transport properties governing the rate of resuspension, and formulate the resuspension flux as a functional of the identified parameters and a system of transport equations. The results will be used as source boundary condition for computational fluid dynamics (CFD) simulation of particle transport and dispersion (T&D) inside a building as a part of CB defense. The results will also be useful for study of indoor air quality to improve building HVAC performance.
|| Description: ||This project will to provide critical boundary conditions for accurate simulation of particle transport and dispersion inside a building. The release rate, i.e. source term model, is identified to be one of the two key technical elements for current and future interior and exterior CFD codes . The resuspension rate of pollutants in the outdoor environment has been extensively studied and experimentally validated for simulation of outdoor transport and dispersion . Need and interest in the resuspension model for indoor environment, however, has arisen since 2001. Current model assumes qualitative approximation (e.g., steady flux of predetermined concentration) for the source term boundary condition in the CFD simulation of internal dispersion. Impact of source model on the simulation accuracy of internal dispersion has been well demonstrated in the previous study . This project is to develop a realistic model for source flux under typical building HVAC environment.
|| ||PHASE I: Investigate the responsible mechanism for fine particles from indoor surfaces. Development of theoretical model for the indoor resuspension of fine particles is the goal of Phase I research. Innovative and creative approach to the model development is encouraged. Demonstration of the theoretical model against experimental data in the published domain will conclude the Phase 1.
|| ||PHASE II: Innovative and creative experiments are expected to verify the theoretical model. The experiments are expected on a number of different types of surfaces and different sizes of particles. Validation of the model will be accomplished by integration of the source term model into an internal T&D CFD code. Demonstration of the improvement in accuracy of internal T&D simulation concludes the Phase 2.
|| ||PHASE III: Integration of the source term model to general T&D CFD codes will be the focus of Phase III activity. Examples for commercial applications include incorporation of the resuspension model to indoor air quality simulation (e.g., CONTAM and/or COMIS) and building energy simulation tools (e.g., Airpak, EnegyPlus). Military application includes incorporation of the model into Joint Effects Module (JEM) codes and Hazard Prediction and Assessment Capability (HPAC). Due to the sensitivity of information, the source term integration into military CFD codes will be strictly coordinated with the appropriate authorities.
|| References: ||1. “Source Term Dose Response Analysis Toolset (STDRAT),” J.E. Broclmann, F. T. Harper and D. Sommerville, DHS Conf paper, Boston, MA, Apr 05.
2. “Evaluation and development of models for resuspension of aerosols at short times after deposition,” G.A. Loosmore, Atmospheric Environment, Vol. 37, pp. 639-647, 2003.
3. “Modeling and Simulation of Dynamic Dispersion Airborne CBR Contaminants in Buildings,” ERDC-CERL, AT41-CFF-A054 and AT45-CFF-X084, 2005
|Keywords: ||Indoor source term, internal transmission and dispersion, CB modeling|