Formula Symbols and Units for Fluidics and Electric Engineering

Formula Symbol Description Unit Note

A Surface, cross sectional area
a Acceleration m/s²
c Drag coefficient
cp Specific isobar heat capacity J/kg K
cv Specific isochor heat capacity J/kg K
D, d Diameter m
E Energy J 1 J = 1 N m = 1 W s = 1 VA s = 1 kg m²/s²
F Force N
f Frequency Hz
f Function of …, factor
g Gravitational acceleration m/s² Gravity ≅ 9.8 m/s²
H Height m
I Pulse Ns 1 Ns = 1 kg m/s
İ Pulsating current N 1 N = kg m/s²
i Pulsating current density Nm², Pa 1 Pa = N/m² = kg/s²m
k Roughness height m
ks Sand roughness height m
L Length m
M Mass kg
Mass flow kg/s
Mass flow density kg/s
m Opening ratio
Mo Momentum
n RPM 1/s
n Number
n Exponent
P Power W 1 W = J/s = 1 Nm/s = 1 VA = 1 kg m²/s³
p Pressure N/m², Pa 1 Pa = 1 N/m² = 1 kg/s² m
r Radius m
r Gas constant J/kg K
s Thickness, wall thickness, length m
T Temperature (Kelvin) K
t Time s
U Scale m
u Speed Component m/s
V Volume
Volumetric flow rate m³/h
v Specific volume m³/kg v = V/M = 1/ρ
v Volumetric flow rate m³/h
v Speed component m/s
W Work J 1 J = 1 Nm = 1 Ws = 1 VAs = 1 kg m²/s²
w Speed m/s
wT Friction velocity m/s
x Coordinate for the direction of flow
y Coordinate transversely to the direction of flow
α Flow coefficient
β Angel rad
δ Boundary layer thickness m
ζ Coefficient of friction
η Viscosity Pa s 1 Pa s = 1 Ns/m² = 1 kg/s m
η Efficiency
ϑ Temperature (Celsius) ° C °C = T-273,15 K
λ Pipe friction factor
μ Contraction coefficient
υ Kinematic viscosity m²/s υ=η/ρ
ρ Density kg/m³ υ=η/ρ
τ Shear stresses N/m², Pa 1 Pa = 1 N/m² = 1 kg/s²m
ψ Cavity proportion