1. Chris Sideroff and Thong Dang Syracuse University
Task 2.C Computation of Transport in PME I. Flow and Pollutant Transport
Chris Sideroff and Thong Dang
Syracuse University

2. “Better” IAQ P.O. Fanger, SU June 06 For high IAQ need to address:
“Healthy Indoor Air, i.e. complete well being, requires more than 20 times higher IAQ”
“A paradigm shift is required”
For high IAQ need to address:
Source control
Air-cleaning
Personal ventilation
Fanger: “Improve quality of breathed air by factor of 10”
Fanger SU Lecture June 2006

3. Overview
Ventilation systems other than the mixing type (e.g. personal, displacement), flow/contaminant gradients are important – cannot use “well-mixed” assumption
Flow/contaminant gradients near manikin are important if prediction of human exposure to contaminants is of interest
Topp et al. 2002
Personal Micro-Environment (PME): region around person which affects her/his breathed air – PME not a well-mixed environment
Interaction of the PME and surrounding environment is a complicated problem and requires accurate tools to tackle it => Task 2
“… when interested in the local air movements around occupants, the results show that a more detailed CSP should be applied as the local velocities were found to be different for the two CSP investigated.” They go on to say “… the local flow plays a role in the transport of contaminants to and from the breathing zone and, thus, the personal exposure”

4. Approach
Characterize and assess IAQ (PME) using Computational Fluid Dynamics
CFD is a potentially efficient (fast/inexpensive) and flexible tool because of advancements in CFD methodologies (modeling of complex geometry and transient problems, advanced RANS turbulence models and LES models) and computing hardware (e.g. parallel computing clusters)
Accuracy of CFD? Determine whether RANS/LES CFD is capable of characterizing/ assessing the PME  EPA02
Develop procedures/guidelines to use CFD for PME  EPA02
Use CFD to increase fundamental knowledge of PME (and IAQ) and as a design tool when theory and/or experiments can not be applied => EPA03

5. Collaboration Task 2C Detailed CFD Task 1 Source Char.
Provide Gaseous Conc. for BC’s
Provide PM Conc. For BC’s
Task 2C Detailed CFD
Task 2A Resusp. Exp.
Task 2B Detailed Exp.
Enhanced Validation and PM measurement
Provide Guidelines for PEL CFD
Task 5A PEL Exp.

6. Current State-of-the-Art
In open literature, grid resolutions are typically on the order of a few hundred thousand (for 3D)
Traditional turbulence models
zero-equation (mixing length)
k-e family
Single-point, omni-directional measurements
velocity magnitude, no components
no turbulence information (length scale, intensity)
better error estimation
Steady-state
if breathing, steady inhalation/exhalation
no motion
Active research group at ASHRAE and Indoor Air – e.g. ASHRAE Chicago (Feb. 2006) Benchmark Symposium (Nielsen, Kato, Chen)

7. EPA03: Realistic Conditions
EPA02 - steady-state validation done
Using validation guidelines proceed to assess exposure under more realistic conditions
Unsteady breathing
Head motion (rotation)
Body motion (rotation)
Foot motion (tapping)
Further validate CFD for realistic setups with T2B (body rotation)
Some important consequences
Difference between exposure in these situations and those using steady-state assumption
Fundamental impact of these effects on the flow (e.g. thermal plume, origin of inhaled air, etc)

8. Breathing
Breathing is a transient process however a common assumption is to assume steady inhale or exhale
Important issues:
Difference in exposure (gaseous contaminant) – is the steady assumption sufficient?
Origin of breathed air – this information could help design of PME
Model the breathing cycle with a sinusoidal curve
Actual (Marr T2B)
Sinusoidal

9. Origin of air: Stationary, Breathing Manikin Movie
Breathing is a transient process however a common assumption is to assume steady inhale or exhale
Important issues:
Origin of breathed air – could help in design strategies of PME
Transient Breathing
Steady Inhalation
Air comes from in front of lower torso region – _not_ directly from feet
Origin of air: Stationary, Breathing Manikin Movie
Gao & Nui 2004

10. Emissions from clothing
Breathing
Breathing is a transient process however a common assumption is to assume steady inhale or exhale
Important issues:
Difference in exposure (gaseous contaminant) – is the steady assumption sufficient? Currently under investigation
T1.A (Zhang - Source characterization) provides information for gaseous contaminant boundary conditions (concentration and/or flux)
Emissions from clothing
Front-cut
Side-cut

11. Rotating Head
People typically are not completely stationary for long periods of time
Rotation of head mimics a person reading
Important issues:
Origin of breathed air – how much does the motion affect where/what we breath?
Difference in exposure compared to 1) breathing alone 2) steady-state
45° Right
22° Right
Centered
22° Left
45° Left
Breathing, Head Rotating Manikin Movie

12. Body Rotation
Large scale motions of people my affect more than small breathing zone – e.g. person swiveling in an office chair
In parallel with T2.B (Glauser) => enhanced validation
Important issues
Does this type of motion disturb the room flow enough to create enhanced mixing, i.e. will it cause the transport of contaminants not otherwise possible?
Fundamental impact of these effects on the flow (e.g. thermal plume, origin of inhaled air, etc)
IFL T2B Setup

13. Foot Motion
The interaction of a foot approaching the floor has been shown (SU work by Khalifa and Elhadidi 2005) to be an important mechanism in particulate matter (PM) resuspension
Simulation of actual motion (rotation & translation) of 3D foot is beyond our capability therefore a model was created that can recreate the flow from a foot approaching a flat surface
We suspect the flow created by this interaction will be an important factor in transport of pollutants and PM (T2.C Ahmadi) away from the floor and eventually into the breathing zone (T2.B Higuchi)
Full 3D foot
Axi-sym. 2D Piston
Body-force Model

14. Foot Motion
Using the guidance of T2.B (Higuchi - piston exp.) and CFD, momentum source constructed mimicking the external flow cause by a falling foot
Simulate transport of PM from falling foot – Boundary conditions for PM (loading and concentration) from T2.A (Ferro)

15. Summary and Continuing Work
Capturing the flow/contaminant gradients are important for PME, hence detailed CFD required
Realistic details of a person in their PME are important - Investigation on the impact of the transient details (breathing and motions) is currently in progress
Interaction and collaboration with others relevant tasks (T1.A, T2.A, T2.B, T5.A) critical for success of detailed simulations