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Contaminate Plume in an Office John Dunec, Ph.D. COMSOL 4.2a. Welcome to the Lunch-Time Tutorials!. Solve One Problem Using COMSOL Multiphysics This Tutorial: Contamination Plume in an Office About 30-35 minutes duration Short Q&A at end Upcoming Tutorials: Gate Valve

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Presentation Transcript
slide1

Contaminate Plume in an Office

John Dunec, Ph.D.

COMSOL 4.2a

welcome to the lunch time tutorials
Welcome to the Lunch-Time Tutorials!
  • Solve One Problem Using COMSOL Multiphysics
  • This Tutorial: Contamination Plume in an Office
  • About 30-35 minutes duration
  • Short Q&A at end

Upcoming Tutorials:

  • Gate Valve
  • Positive Displacement Pump
  • One-Way Flapper Valve

www.comsol.com/events

multiphysics multiple interacting phenomena
Multiphysics: Multiple Interacting Phenomena

Could be simple:

  • Heat convected by Flow

Could be complex:

  • Local temperature sets reaction rates
  • Multiple exothermic reactions
  • Convected by flow in pipes and porous media
  • Viscosity strongly temperature dependent
comsol multiphysics
COMSOL Multiphysics
  • Multiphysics – Everything can link to everything.
  • Flexible – You can model just about anything.
  • Usable – You can keep your sanity doing it.
  • Extensible – If its not specifically there…add it!

Trusted by 80,000+ Users Worldwide

contaminate plume in an office
Contaminate Plume in an Office
  • Convection Dominated diffusion lead to numerical instabilities
  • Use Particle Tracing Module instead
  • Particle Release in Hallway
  • How much gets into office?

10 micron Particles

Air Velocity

slide6

COMSOL Products Used – This Tutorial

  • Navier-Stokes from COMSOL Multiphysics
  • (Turbulence would require CFD or Heat Xfer or Chem Rx Engrg)
  • Particle Tracing Module
tutorial roadmap
Tutorial Roadmap

Air Velocity

First: Setup and Solve AirFlow

  • Choose Physics
  • Import Geometry Sequence
  • Choose Materials (Air)
  • Set Inlet & Outlet B.C.’s
  • Mesh
  • Solve

Next: Add Particle Tracing

Finally: Results Statistics

10 micron Particles

flow boundary conditions
Flow Boundary Conditions
  • 10’ x 10’ Office
  • Office Door Wide Open
  • Both Office Windows Open
  • Light Breeze Down Hallway. V = 0.15 m/s

P=0

P=0

Office

Door

Hallway

Hallway

P = 0

V=0.15

disclaimer this flow is actually turbulent
Disclaimer! This Flow is Actually Turbulent
  • Checking the Reynolds number – This should be turbulent flow

The Problem Size gets much bigger

  • Turbulence requires a much denser mesh
  • Turbulence introduces more variables to calculate

For this example we will ignore this(It’s a classroom example!)

  • Want a quick solution
  • Want small memory requirements
  • Will show at conclusion of problem how to solve with turbulence
a few comsol gui pointers
A Few COMSOL GUI Pointers
  • Everything you do is recorded in the Model Builder
  • When in doubt … Right Click!
while it s solving what about turbulence
While it’s Solving … What about Turbulence?

Requires either the CFD or Heat Transfer or Chem Rx Engr’g Module

  • k-epsilon
  • Low Re k-epsilon
  • k-omega
  • Spalart-Allmaras
simulation should be done now
Simulation Should be Done Now!
  • Takes ~ 60 seconds on my desktop
tutorial roadmap1
Tutorial Roadmap

Air Velocity

DONE: Setup and Solve AirFlow

Next: Add Particle Tracing

  • Add 2nd Physics
  • Set Particle Properties
  • Add Particle Forces (Drag)
  • Define Inlets & Outlets
  • Set What to do at Walls
  • Add Transient Study
  • 2-Step Solution

Finally: Results Statistics

10 micron Particles

while it s solving what about turbulence1
While it’s Solving … What about Turbulence?

Requires either the CFD or Heat Transfer or Chem Rx Eng’g Module

  • k-epsilon
  • Select Turbulent Disp. in Force Window
  • Link to Turbulence Model in Flow
  • Generates random-normal forces on particle to include forces from turbulent eddies
particle release options
Particle Release Options

Release on Boundary

  • Mesh based
  • Boundary Area based
  • Boundary Grid based

Release in Volume

  • Coordinate-based
mesh based particle release inlet node
Mesh Based Particle Release (Inlet Node)

Refinement factor = 1

Refinement factor = 2

density based particle release inlet node
Density Based Particle Release (Inlet Node)

Expression = 1

Expression = 1/(x2+y2)

projected plane grid inlet node
Projected Plane Grid (Inlet Node)
  • Aligns with x – y – z coordinate axes
grid based release from grid
Grid Based (Release from Grid)

Distributed over Domain

simulation should be done now1
Simulation Should be Done Now!
  • Takes ~ 65 seconds on my desktop
tutorial roadmap2
Tutorial Roadmap

Air Velocity

DONE: Setup and Solve AirFlow

DONE: Add Particle Tracing

Finally: Results Statistics

  • Duplicate Results Dataset (2x)
  • Add Selections – Office
  • Add Selections – Window
  • Calculate Transmission Probability

10 micron Particles

review
Review

Air Velocity

Setup and Solve AirFlow

  • Geometry & Materials
  • Inlets/Outlets
  • Mesh & Solve

DONE: Add Particle Tracing

  • Particle Properties
  • Forces on Particles
  • Inlets / Outlets
  • Solve with Transient

Finally: Results Statistics

  • Transmission Probability

10 micron Particles

to get more information
To Get More Information …

Attend a Free Seminar

  • Includes 2-week trial of COMSOL
  • www.comsol.com/events

Attend our Webinars

  • www.comsol.com/events/webinars/

Contact Your Local COMSOL Office

  • www.comsol.com/contact

Attend our Annual Conference

  • www.comsol.com/conference2012
capture the concept tm
Capture the ConceptTM

Addendum Step-by-Step Instructions

start by solving for airflow
Start by Solving for Airflow
  • Choose File > New
  • Select “3D”
  • Select “Fluid Flow” > “Single Phase Flow” > “Laminar Flow”
  • Choose “Stationary”
disclaimer this flow is actually turbulent1
Disclaimer! This Flow is Actually Turbulent
  • Checking the Reynolds number – This should be turbulent flow

The Problem Size gets much bigger

  • Turbulence requires a much denser mesh
  • Turbulence introduces more variables to calculate

For this example we will ignore this(It’s a classroom example!)

  • Want a quick solution
  • Want small memory requirements
  • Will show at conclusion of problem how to solve with turbulence
set up geometry import sequence
Set up Geometry – Import Sequence
  • Choose Geometry
  • Change “Units” to “Feet”
  • Right click on Geometry
  • Choose “Import Sequence from File”
  • Navigate to proper file location (probably on CD)
  • Choose “ContaminationPlume_GEOM_SEQUENCE”
  • Build All, Zoom Extents

Or you can build it from scratch (instructions at end of presentation)

material air
Material: Air
  • Rt Click on “Materials”
  • Choose “Material Browser”
  • Expand “Built-in”
  • Choose “Air”
  • Be sure “All Domains” are selected
airflow inlet boundary conditions
Airflow: Inlet Boundary Conditions
  • Rt Click on “Laminar Flow”
  • Choose “Inlet”
  • Choose the end of the hallway near the door
  • Set to “Velocity”
  • Normal inflow velocity
  • U0 set to “0.15”
airflow outlet boundary conditions
Airflow: Outlet Boundary Conditions
  • Rt Click on “Laminar Flow”
  • Choose “Outlet”
  • Choose the other end of the hallway
  • Choose both windows
  • Set to “Pressure, no viscous stress”
  • P0 set to “0”
mesh physics based mesh
Mesh: Physics-based Mesh
  • Highlight “Mesh”
  • Leave as “Physics-controlled mesh”
  • Set size as “Extra Coarse”
  • Build

Note: This is way too coarse for accurate flow

give the nonlinear solver more iterations
Give the Nonlinear Solver more Iterations
  • Rt Click on “Study 1”
  • Select “Show default solver”
  • Expand everything under Study 1
  • Highlight “Fully Coupled”
  • Change iterations from 25 to 50

Note: This controls max number of Newton iterations before giving up.

solve for flow
Solve for Flow
  • Rt Click on Study 1
  • Hit “Compute”
  • Under Results:
  • Rt Click on “Velocity”
  • Choose “Slice”
  • Choose “Quick”
  • Choose “xy-plane”
  • Planes: “1”
  • Plot
add particle tracing
Add Particle Tracing
  • Rt click on “Model 1”
  • Choose “Add Physics”
  • Choose “Fluid Flow” > “Particle Tracing for Fluid Flow”
  • Choose the blue “Next” arrow
  • Choose “Time Dependant”

Note: You need an additional study since particle tracing is transient whereas the fluid flow was stationary.

set particle properties
Set Particle Properties
  • Open “Particle Tracing for Fluid Flow”
  • Highlight “Particle Properties 1”
  • Change to “Specify density & diameter”
  • Density: 2200
  • Diameter: 10e-6
  • Charge number: 0
add fluid forces
Add Fluid Forces
  • Rt Click on “Particle Tracing for Fluid Flow”
  • Choose “Drag Force”
  • Select “All Domains”
  • Set “u” to “Velocity Field”

Note: for Turbulent flows (typical for room dispersion) you must select “Turbulent dispersion” in the “Drag Force” section.

Do not select this in this tutorial

bc particle inlet
BC: Particle Inlet
  • Rt Click on “Particle Tracing for Fluid Flow”
  • Choose “Inlet”
  • Select hall boundary near door
  • Change “Initial position” to “Density”
  • Set “N” to “1000”
  • Set density to “1”
  • Set Initial Velocity to “Velocity field”
bc particle outlets
BC: Particle Outlets
  • Rt Click on “Particle Tracing for Fluid Flow”
  • Choose “Outlet”
  • Choose the other end of the hallway
  • Choose both windows
  • Leave as “Freeze”

Note: The other likely setting is “disappear” – but then we cannot do statistics on the particles later

walls change condition to bounce
Walls – Change Condition to “Bounce”
  • Under “Particle Tracing for Fluid Flow”
  • Highlight “Wall 1” Node
  • Change “Freeze” to “Bounce”
assign stationary solver to flow only
Assign Stationary Solver to Flow only
  • Expand “Study 1”
  • Highlight “Step 1: Stationary”
  • In the “Physics Selection”:
  • Deselect “Particle Tracing for Fluid”
assign transient solver to particle tracing
Assign Transient Solver to Particle Tracing
  • Expand “Study 2”
  • Highlight “Step 1: Time Dependant”
  • In the “Physics Selection”:
  • Deselect “Laminar Flow”
  • Expand the “Values of Dependent Variables” section
  • Select “Values of variables not solve for”
  • Method: “Solution”
  • Study: “Study 1, Stationary”
  • Stationary: “Automatic”

Note: This uses the flow solution obtained in study 1

set times and solve
Set Times and Solve
  • Highlight “Step 1: Time Dependant”
  • Choose the “Range” button
  • Start: “0”
  • Stop: “360”
  • Step: “2”
  • Rt Click on Study 2
  • Hit Compute
add particle path lines
Add Particle Path Lines

Under Results:

  • Expand “Particle Trajectories”
  • Highlight “Particle Trajectories 1”
  • Change “Line style” from “None” to “Line”
set up transmission probability
Set up Transmission Probability
  • Expand “Data Sets” under “Results”
  • Rt Click on “Particle 1” > Select “Duplicate”
  • Rt Click on “Particle 2” > Rename as “Particle 2 – RoomOnly”
  • Rt Click on Particle 2 > Add Selection
  • Choose ONLY room domain
  • Rt Click on “Derived Values” > Choose “Global Evaluation”
  • Dataset: Particle 2
  • Time Selection: Last
  • Select expression as “Transmission Probability”
  • Hit the “=“ sign to evaluate (27%)
capture the concept tm1
Capture the ConceptTM

Geometry Steps

set up geometry floor plan workplane
Set up Geometry – Floor plan Workplane
  • Choose Geometry
  • Change “Units” to “Feet”
  • Right click on Geometry
  • Choose “Workplane”
  • Select “Quick plane” “xy-plane”
  • Choose the “Show Workplane” button
2d floorplan geometry main room
2D Floorplan Geometry: Main Room
  • Right click on Geometry (under Workplane 1)
  • Choose: Rectangle
  • Width: 15
  • Height: 10
  • Position: Corner
  • X: 0
  • Y: 0
  • Build
2d floorplan geometry hallway
2D Floorplan Geometry: Hallway
  • Right click on Geometry (under Workplane 1)
  • Choose: Rectangle
  • Width: 20
  • Height: 4
  • Position: Corner
  • X: -5
  • Y: -4.5
  • Build
2d floorplan geometry jog in hallway
2D Floorplan Geometry: Jog in Hallway
  • Right click on Geometry (under Workplane 1)
  • Choose: Rectangle
  • Width: 3
  • Height: 10
  • Position: Corner
  • X: 12
  • Y: -14.5
  • Build
2d floorplan union hallway rectangles
2D Floorplan: Union Hallway Rectangles
  • Right click on Geometry
  • Choose: Boolean Operations > Union
  • Deselect “Keep Interior Boundaries”
  • Choose the two Hallway Rectangles
  • Build
3d geometry extrude room and hallway
3D Geometry: Extrude Room and Hallway
  • Rt Click on “Workplane 1”
  • Choose “Extrude”
  • Set Distance as 8 [ft]
  • Build
3d geometry doorway workplane
3D Geometry– Doorway Workplane
  • Right click on Geometry
  • Choose “Workplane”
  • Select “Face Parallel”
  • Choose the Room wall that is closest to the hallway
  • Choose the “Show Workplane” button
2d door outline door rectangle
2D Door Outline: Door Rectangle
  • Right click on Geometry (under Workplane 2)
  • Choose: Rectangle
  • Width: 3
  • Height: 6.5
  • Position: Corner
  • X: 3
  • Y: -2.5
  • Build
3d geometry extrude doorway
3D Geometry: Extrude Doorway
  • Rt Click on “Workplane 2”
  • Choose “Extrude”
  • Set Distance as 0.5 [ft]
  • Build
3d geometry window workplane
3D Geometry– Window Workplane
  • Right click on Geometry
  • Choose “Workplane”
  • Select “Face Parallel”
  • Choose the Room wall that is farthest from hallway, but parallel to hallway
  • Choose the “Show Workplane” button
2d door outline 1 st window
2D Door Outline: 1st Window
  • Right click on Geometry (under Workplane 3)
  • Choose: Rectangle
  • Width: 3
  • Height: 4
  • Position: Corner
  • X: -5
  • Y: -2
  • Build
2d door outline 2 nd window
2D Door Outline: 2nd Window
  • Right click on Geometry (under Workplane 3)
  • Choose: Rectangle
  • Width: 3
  • Height: 4
  • Position: Corner
  • X: 2
  • Y: -2
  • Build
build 3d geometry to add windows
Build 3D Geometry to Add Windows
  • Highlight “Geometry 1” in model builder
  • Choose “Build all” button