the university of texas at austin spring 2013 caee department
DESCRIPTION
The University of Texas at Austin Spring 2013 CAEE Department Course : Modeling of Air and Pollutant Flows in Buildings Instructor : Dr. Atila Novoselac Office: ECJ, 5.422 Phone: (512) 475-8175 e-mail: [email protected] - PowerPoint PPT PresentationTRANSCRIPT
The University of Texas at Austin Spring 2013CAEE Department
Course: Modeling of Air and Pollutant Flows in Buildings
Instructor: Dr. Atila Novoselac Office: ECJ, 5.422 Phone: (512) 475-8175 e-mail: [email protected]://www.ce.utexas.edu/prof/Novoselac
Office Hours: Tuesday and Thursday 11:00 a.m.–12:00 p.m.
• Discuss the Syllabus• Describe scope of the course• Introduce the course themes• Answer your question • Fluid dynamics review
Today’s Lecture Objectives:
Introduce Yourself
• Name • Background
- academic program and status• Professional interests• Reason(s) for taking this course
Motivation for Modeling of Indoor Air Distribution using CFD:
• Major exposure to contaminant is in indoor environment
• Ventilation system provides contaminant dilution Controlled airflow (ventilation) can considerably improve the IAQ and reduce the ventilation air requirement
• Air-flow transports pollutants – gaseous and particulate
• Contaminant concentration in the space is more or less non-uniform – It affects: emission, filtration, reactions, exposure
Why to Care About Indoor Airflow Distribution ?
Pollutant concentration is very often non-uniform
- Exposure depends on dispersion
Perfect mixing
SinksSourcesdtdC
SinksSources
zCD
yCD
xCD
zCV
yCV
xCV
tC
zyx 2
2
2
2
2
2
We can control exposure by controlling the flow field
Examples of Exposure Control by Ventilation Systems
1) Control Exhaust
2) Control Supply
Supplydiffusers
Heater (radiator)
Example of Buoyancy Driven Flow:Airflow in a Stairwell
Example of Force Convection Contaminant Concentration in a Kitchen
Example Particle Dispersion
Fluid DynamicsContinuity:
Momentum:
Numerical Methods
Simulation Software (CFD)
Simulation SoftwareIf Garbage IN
ThenGarbage OUT
Input Output
• Recognize the physics behind various numerical tools used for solving airflow problems.
• Employ basic numerical methods for solving Navier-Stokes Equations.
• Apply CFD for airflow simulations in buildings and use these tools in design and research.
• Evaluate the thermal comfort and indoor air quality (IAQ) with different ventilation systems.
• Assess human exposure to different pollutant types.
• Critically analyze and evaluate CFD results.
Course Objectives
Topics:
1. Course Introduction and Background 1 wk2. Fundamentals of fluid dynamics 2 wks3. Turbulence models 1.5 wks
4. Numerical methods and parameters 2 wks5. CFD modeling parameters 1.5 wks6. Introduction to CFD software 1 wk
7. Application of CFD for building airflows 1 wk8. Simulation of IAQ parameters 1 wk9. Simulation of thermal comfort parameters 1 wk10. Modeling of aerosols 1 wk11. Air and pollutant flows in the vicinity of occupants 1 wk12. Accuracy and validation of building airflow simulations 1 wk
30%
30%
40%
Prerequisites
- Fluid Dynamics
Knowledge of the following is useful but not necessary:
- HVAC systems- Numerical analysis- Programming
Textbook1) An Introduction to Computational Fluid Dynamics,
Versteeg, H.K. and Malalasekera, W.
References: 2) Computational Fluid Dynamics –The Basics With
ApplicationsAnderson
3) Turbulence Modeling for CFD Wilcox
Handouts
• Copies of appropriate book sectionsAn Introduction to Computational Fluid Dynamics I will mark important sections
• Disadvantage - different nomenclature• I will point-out terms nomenclature and terminology
differences
• Journal papers and CFD software manual• Related to application of airflow simulation programs
Energy simulation software
Airpark Fluent
There is a large availability of CFD software !
- Star CD We have it and you will use it
- Phoenics- CFX - Flow Vent
Star CD Software – Air Quality in the Airplane Cabin
TENTATIVE COURSE SCHEDULE
TENTATIVE COURSE SCHEDULEContinues from previous page
Test 25%Homework Assignments 30%Midterm Project 10%Final Project & Presentation 30%Classroom Participation 5%
100%
Grading
Participation 5%
• Based on my assessment of your participation in the class
• How to get participation points• Come to class• Submit all assignments/projects on time• Participate in class discussions• Come to see me in my office
Homework 30% (each 10%)
Total 3
• HW1Problems related to fluid dynamic
• HW2Problem related to turbulence modeling
• HW3 Problem related numeric
Midterm Exam 25%
• Out -class exam (90 minutes)
• At the the end of March - we will arrange the exact time
• Problems based on topics cover in the first two parts of the course
Midterm Project 10%• Individual project
• Use of CFD program for air and pollutant flow analysis
• Primary goal is to get familiar with the CFD software
Final Project 30%
• Use of CFD for detail airflow, thermal and IAQ analyses
• Different projects topics– Real engineering an/or research problems
• Final presentation (10-15 minutes)
Previous Course projects -Human Exposure to toxins
Previous Course projects- Surface Boundary Layer
Previous Course Projects - Hydro-Jet Screen
Previous Course projects - Natural Ventilation
• Design of ventilation system
• Smoke management
• Natural ventilation
• Human exposure to various pollutants
• Your suggestion
More CFD Final Project:
Grading
> 93 A 90-93 A-86-90 B+
83-86 B 80-83 B-
< 80 C-, C, C+
Course Website All course information:http://www.ce.utexas.edu/prof/Novoselac/Classes/ARE372/
• Except your grades and HW solutionsGrades and progress on the Blackboard
• On the course website • Look at Assignments sections• Review class material ahead of time
use posted class notes
My Issues
• Please try to use office hours for questions problems and other reasons for visitTuesday and Thursday morning reserved - Class preparation
• Please don’t use e-mail to ask me questions which require long explanations• Come to see me or call me
• Suggestions are welcome• The more specific the better
Fluid Dynamics
Review
Conservation equations
Important operations
kz
jy
ix
grad
zV
yV
xVVdiv zyx
zV
yV
xV
DD
zyx
Vector and scalar operators:
)()()()()( zzyyxxzyxzyx VUVUVUkVjViVkUjUiUVU
Total derivative for fluid particle which is moving:
x
z
y
vector
scalar
V
any scalar
Continuity equation -conservation of mass
0
flow
0
zw
yv
xu
ibleIncompresszw
yv
xu
Mass flow in and out of fluid element
Change of density in volume == Σ(Mass in) - Σ(Mass out)
……………….……………….
Volume V = δxδyδz Infinitely small volume
Volume sides: Ax = δyδz Ay = δxδz Az = δxδy
Shear and Normal stress
τyx
Momentum equation –Newton’s second law
Stress components in x direction
DDv
DDv
DDv
zyx particle fluid of for volume and DDvaFor
Fam Fam Fam :or Fam
zyx
zzyyxx
zyx fff
totalderivative
forcesper unit of volume in direction x
………………..…………………………….
dimensions of fluid particle
DDvx
xf
Momentum equation
Sum of all forces in x direction
xzyx Sz
Vy
Vx
V
zyxxp)vvvv( zxyxxxxxxx
xS
zyxx
pDDv zxyxxxx
xx Sf
zyxx
p zxyxxx
Internal source
yzyx Sz
Vy
Vx
V
zyxyp)
vvvv( zyyyxyyyyy
zzyx Sz
Vy
Vx
V
zyxzp)vvvv( zzyzxzzzzz
x direction
y direction
z direction
Newtonian fluids• Viscous stress are proportional to the rate of deformation (e)
zv e ,
yv
e , xve z
zzy
yyx
xx
yv
zv
21ee ,
xv
zv
21ee ,
xv
yv
21ee zy
zyyzzx
zxxzyx
yxxy
Elongation:
Shearing deformation:
Viscous stress:
)(xv2 x
xx zV
yV
xV zyx
yv
zv
, xv
zv ,
xv
yv zy
zyyzzx
zxxzyx
yxxy
zv 2 ,
yv
2 , xv2 z
zzy
yyx
xx
0
For incompressible flow
viscosity
Momentum equations for Newtonian fluids
yzyx Sz
Vy
Vx
V
zyvμ
yv
μxy
vμzv
yv
xv
yp)
vvvv( z
2
2y
2x
2
2y
2
2y
2
2y
2yyyy
xz
2y
2
2x
2
2x
2
2x
2
2x
2x
zx
yx
xx S
zxvμ
yxv
μxvμ
zvμ
yvμ
xvμ
xp)
zvV
yvV
xvV
τvρ(
x direction:
y direction:
z direction:
zzyx Sz
Vy
Vx
V
2z
2y
2x
2
2z
2
2z
2
2z
2zzzz
zvμ
yzv
μxz
vμzv
yv
xv
zp)vvvv(
After substitution: