Convection

Question 1

What is the boundary of velocity boundary layer?

Answer 1

u = 0.99v

Question 2

Boundary layer region refers to what region with what properties?

Answer 2

When fluid affected by presence of wall, and theres significant viscous effect and velocity changes.

Question 3

Irrotational flow region refers to?

Answer 3

Region with negligible frictional effect and constant velocity

Question 4

Fully developed pipe flow refers to

Answer 4

Fluid flow not affected by wall presence and velocity remains unchanged. Boundary layer covers entire pipe

Question 5

Thermal boundary layer boundaries?

Answer 5

T-Ts = 0.99(Tfluid - Tsurface)

Question 6

Formula for average h

Answer 6

1/L * integration of hx to limits L & 0

Question 7

Steps to find Q if Pr given?

Answer 7

1) Find Re
2) Find Nu using Re and Pr
3) Find h using Nu
4) Find Q

Question 8

What is Natural Conv?

Answer 8

fluid motion caused by buoyancy forces

Question 9

What are buoyancy forces?

Answer 9

Forces induced by density diff due to temp diff

Question 10

Significance of vol expansion coefficient?

Answer 10

measure of volume change of a substance w temp at a constant pressure

Question 11

What does Nu indicate?

Answer 11

> 1 => convection

Question 12

What is Prandtl?

Answer 12

Ratio of fluid momentum vs fluid heat diffusivity

Question 13

What is turbulent Re

Answer 13

Re > 3 x 10^5 or Re > 10^5

Question 14

Significance if Grashof?

Answer 14

Whether conv is natural of forced, >1 => natural

Question 15

Find Q if Gr or B given.

Answer 15

1) Find Gr no. using B
2) Find Ra
3) Find Nu empirically
4) Find h
5) Find Q