Ah	Cross-sectional area of hose	Qmax	Maximum air flow rate
$A_o$	Orifice cross-sectional area	r	Abrasive loading ratio
$C_d$	Coefficient of discharge	$\dot{r}$	Radia velocity
CD	Drag coefficient	R	Ratio of Xc/dn
dh	Hose diameter	Rw	Waviness
dm	Mixing tube diameter	sa	Abrasive particle-specific gravity
dn	Orifice diameter	t	Time
dp	Particle diameter	tb	Trailback
Ew	Jet hydraulic power	u	Material displacement rate
Ea	Abrasive kinetic power	Va	Abrasive particle velocity
Ewd	Waterjet power density	Vw	Waterjet velocity
f	Flow friction coefficient	X	Distance along the jet
h	Cutting depth	Xc	Jet initial zone length
hc	Depth due to cutting wear	x	Distance along the mixing tube length
hd	Depth due to deformation wear	w	Jet width in the main region
lm	Mixing tube length	λ	Particle velocity ratio
${\dot{m}}_a$	Abrasive flow rate	μ	Abrasive–solid friction coefficient
${\dot{m}}_w$	Water flow rate	$\nu$	Abrasive velocity ratio
$P$	Pressure	${\rho }_o$	Water density
Pa	Ambient pressure	$\eta$	Abrasive power efficiency
Pr	Pressure ratio (Pa − Pv)/Pa	σf	Material strength property
Pv	Vacuum (or suction) pressure	${\zeta }_o$	Momentum transfer efficiency
Q	Water flow rate