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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: atila@mail.utexas.edu
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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: atila@mail.utexas.edu http://www.ce.utexas.edu/prof/Novoselac Office Hours: Tuesday and Thursday 11:00 a.m.–12:00 p.m.
Today’s Lecture Objectives: • Discuss the Syllabus • Describe scope of the course • Introduce the course themes • Answer your question • Fluid dynamics review
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 • We can control exposure by controlling the flow field Perfect mixing
Examples of Exposure Control by Ventilation Systems 1) Control Exhaust 2) Control Supply Supply diffusers
Example of Buoyancy Driven Flow:Airflow in a Stairwell Heater (radiator)
Example of Force Convection Contaminant Concentration in a Kitchen
Fluid Dynamics Continuity: Momentum:
Simulation Software (CFD) Simulation Software Input Output If Garbage IN Then Garbage OUT
Course Objectives • Recognize the physics behind various numerical tools used for solving airflow problems. • Employ basic numerical methods for solving Navier-Stokes Equations. • ApplyCFD 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.
Topics: 1. Course Introduction and Background 1 wk 2. Fundamentals of fluid dynamics 2 wks 3. Turbulence models 1.5 wks 4. Numerical methods and parameters 2 wks 5. CFD modeling parameters 1.5 wks 6. Introduction to CFD software 1 wk 7. Application of CFD for building airflows 1 wk 8. Simulation of IAQ parameters 1 wk 9. Simulation of thermal comfort parameters 1 wk 10. Modeling of aerosols 1 wk 11. Air and pollutant flows in the vicinity of occupants 1 wk 12. 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
Textbook • An Introduction to Computational Fluid Dynamics, Versteeg, H.K. and Malalasekera, W. References: 2) Computational Fluid Dynamics –The Basics With Applications Anderson 3) Turbulence Modeling for CFD Wilcox
Handouts • Copies of appropriate book sections An 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 Fluent Airpark
There is a large availability of CFD software ! • Star CD We have it and you will use it - Phoenics • CFX • Flow Vent
TENTATIVE COURSE SCHEDULE Continues from previous page
Grading Test 25% Homework Assignments 30% Midterm Project 10% Final Project & Presentation 30% Classroom Participation 5% 100%
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 • HW1 Problems related to fluid dynamic • HW2 Problem 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)
More CFD Final Project: • Design of ventilation system • Smoke management • Natural ventilation • Human exposure to various pollutants • Your suggestion
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 solutions Grades 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 visit Tuesday 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
Important operations Total derivative for fluid particle which is moving: V z any scalar y x Vector and scalar operators: scalar vector
Continuity equation -conservation of mass Mass flow in and out of fluid element Infinitely small volume Volume V = δxδyδz Volume sides: Ax = δyδz Ay = δxδz Az = δxδy Change of density in volume = = Σ(Mass in) - Σ(Mass out) ………………. ……………….
Momentum equation –Newton’s second law dimensions of fluid particle Stress components in x direction forces per unit of volume in direction x ……………….. ……………… ……………. total derivative
Momentum equation Sum of all forces in x direction Internal source x direction y direction z direction
Newtonian fluids Viscous stress are proportional to the rate of deformation (e) Elongation: Shearing deformation: For incompressible flow Viscous stress: 0 viscosity
Momentum equations for Newtonian fluids After substitution: x direction: y direction: z direction: