Chapter6

Chapter6 - Copyright 2003 John Baldwin 1 ChEn 323 –...

This preview shows pages 1–6. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Copyright 2003 John Baldwin 1 ChEn 323 – Chapter 6 – Slide 1 Revised Class Schedule 12-13 Ch 13 Ch 13 Ch 12 7/28 Review Presentations Ch 11 Ch 10 N/A Ch 7&8 Ch 6 Ch 5 Ch 3 Ch 1 Monday None Final (on Tuesday) 8/11 None 8/4 11 Ch 12 Exam 7/21 9-10 Ch 11 Ch 10-11 7/14 7-8 Ch 9-10 Ch 9 7/7 None N/A Ch 8 6/30 6 Ch 7 Ch 6 6/23 None Exam Review 6/16 2-5 Ch 5 Ch 4 6/9 1 Ch 3 Ch 2 6/2 H/W Friday Wednesday Week * - Homework due on Wednesday ChEn 323 – Chapter 6 – Slide 2 Introduction to Convection & Until now, convection effects have been treated as boundary conditions for conduction calculations & Our focus on convection will consider the following in parallel: § Heat transfer (thermal) § Mass transfer (concentration) § Velocity profiles & Convection heat and mass transfer § Heat transfer § Mass transfer ( 29 ( 29 ∞ ∞- =- = ′ ′ = ∫ ∫ T T A h hdA T T dA q q S S A S S A S S S ( 29 ( 29 ∞ ∞- =- = ″ = ∫ ∫ , , , , A S A S m A S m A S A A S A A C C A h dA h C C dA N N S S Copyright 2003 John Baldwin 2 ChEn 323 – Chapter 6 – Slide 3 Velocity Boundary Layer = ∂ ∂ = y S y u m t & Zero velocity at surface & Velocity boundary layer bounded by d (x) which is normally defined to be where the velocity is 0.99 of the free stream velocity & At wall, & for Newtonian fluid, m ~ dynamic viscosity ChEn 323 – Chapter 6 – Slide 4 Thermal Boundary Layer & By Fourier’s Law, since there is no motion at surface. = ∂ ∂- = ′ ′ y f S y T k q Copyright 2003 John Baldwin 3 ChEn 323 – Chapter 6 – Slide 5 Concentration Boundary Layer & By Fick’s Law at y=0, & Please note that while d , d t , and d c are similar; they are not necessarily the same value for a particular flow situation. = ∂ ∂- = ′ ′ y A AB A y C D N ChEn 323 – Chapter 6 – Slide 6 Velocity Boundary Layer Development & Note sub layers: even in turbulent flow, there is a laminar sub layer & Sub layers are a function of localized Reynolds number: & Normally, transition at: m r x u x ∞ = Re 5 , 10 5 Re × = = ∞ m r c c x x u Copyright 2003 John Baldwin 4 ChEn 323 – Chapter 6 – Slide 7 Variation of Boundary Layer Thickness ChEn 323 – Chapter 6 – Slide 8 Boundary Layers on an Arbitrary Surface Note: & Multiple boundary layers & Control volume Copyright 2003 John Baldwin 5 ChEn 323 – Chapter 6 – Slide 9 Conservation of Mass & Focus on a control volume as shown on the left. & Assume unit distance in z direction. & Note that density and velocity may vary with x. ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 = ∂ ∂ + ∂ ∂ = ∂ ∂ +- ∂ ∂ +- + y u x u dx dy y u u dy dx x u u dx u dy u r r r r r r r r : to reduces which This is the Continuity Equation ChEn 323 – Chapter 6 – Slide 10 Newton’s Second Law of Motion & The Second Law states that the sum of all forces acting on...
View Full Document

{[ snackBarMessage ]}

Page1 / 15

Chapter6 - Copyright 2003 John Baldwin 1 ChEn 323 –...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online