a

sonic speed

A

cross-sectional flow area of a pipe

C_d

discharge coefficient

c_p

specific heat, constant pressure

c_v

specific heat, constant volume

D

diameter of a pipe

e

internal energy

f

friction factor

F

Force

F_f

Parameter in Equation 18

F_g

Parameter in Equation 18

F_To

Parameter in Equation 18

F_g

Parameter in Equation 18

g

gravitational constant

h

internal convection coefficient

h

enthalpy, static

h_o

enthalpy, stagnation

k

thermal conductivity

K

loss factor

L

length of a pipe

ṁ

mass flow rate

M

Mach number

n

constant

Nu

Nusselt number

P

pressure, static

P_h

heater perimeter

P_o

pressure, stagnation

P_w

wetted perimeter

Pr

Prandtl number

q

heat rate to a pipe

Q

volumetric flow rate

q''

heat flux

r

radius

r

relaxation

R

gas constant

Re

Reynolds number

s

fan speed

s

entropy

T

temperature, static

T_o

temperature, stagnation

U

overall heat transfer coefficient

v

specific volume

V

volume

V

velocity

w

work

x

distance along pipe centerline

z

elevation

Z

compressibility factor

a, m, q

angle

β

diameter ratio

ε

roughness

γ

specific heat ratio

μ

dynamic viscosity

ρ

density

τ

shear stress

ω

rotational velocity

1

location 1 in pipe

2

location 2 in pipe

i

junction at which solution is sought

j

junctions with pipes connecting to junction i

o

stagnation

∞

infinity, far away, ambient