Aerosol Dispersion Modeling With a Low-Cost Flow Simulation Tool: Analysis of Performance and Boundary Condition Sensitivity

Abstract

Understanding the dispersion of potentially infectious aerosols released from breathing and speaking is critical to maintaining a healthy indoor environment. This study used a low-cost commercial off-the-shelf flow simulation tool (SolidWorks Flow Simulation) to model aerosol dispersion within a university classroom and assessed its utility by comparing results to those from physical experiments. A SolidWorks model of a university classroom was created using parameters from a series of full-scale carbon dioxide tracer gas release experiments previously conducted in the physical classroom at both low (520 cfm) and high (900 cfm) flowrates. Steady state concentrations at 13 monitoring points throughout the room were obtained from the flow simulation tool and compared to the experimental results using four performance measures for dispersion model evaluation [15]. The performance measures for the baseline model fell within published acceptance criteria for Fractional Mean Bias (FB), Normalized-Mean Square Error (NMSE), Fraction of Cpredicted within a factor of two of Cobserved (FAC2), and Normalized Absolute Difference (NAD). A sensitivity analysis revealed that the most critical boundary condition for creating an optimum model in both cases was the student heat flux. Adding a simulation of body heat from the silhouettes improved the FAC 2 in the low flow case from 0.08 to 1.0, the NMSE from 1.19 to 0.14, the FB from 0.91 to 0.30, and the NAD from 0.45 to 0.15. Given the ability of SolidWorks Flow Simulation to function as a viable first pass modeling method at a low cost, this accessible tool could be used by a variety of interested parties to quickly predict the spread of aerosols, gases, and other passive scalars under a variety of ventilation and physical arrangement conditions. This software tool may already be available to many academic institutions and provides a reasonable expectation of accuracy.

Classroom aerosol dispersion modeling: experimental assessment of a low-cost flow simulation tool

“…23 Another study by Hirn et al , which was a precursor to the study herein, used the SolidWorks tool to perform a sensitivity analysis of boundary conditions for a flow simulation model of a classroom. 24…”

“…23 Another study by Hirn et al, which was a precursor to the study herein, used the SolidWorks tool to perform a sensitivity analysis of boundary conditions for a ow simulation model of a classroom. 24 Although modeling has the advantage of being precise and repeatable, it is not necessarily accurate. Evaluation of its accuracy relies upon the comparison of model predictions to experimental measurements.…”