$\alpha$	stirrer helix angle	${}^{\circ }$
d	stirrer diameter	mm
n	rotating speed	rpm
$F_T$	tangential collision force	N
$F_N$	normal collision force	N
f	collision frequency	s${}^{-1}$
P	stirrer power	kW
E	collision energy	J/S
R	energy conversion rate	−
$F_{\varphi 15-\varphi 15}$	average collision force between $\varphi$15 mm media	N
$F_{\varphi 15-\varphi 22}$	average collision force between $\varphi$15 mm and $\varphi$22 mm media	N
$F_{\varphi 22-\varphi 22}$	average collision force between $\varphi$22 mm media	N
$\Delta t$	saving time interval	s
$n_i$	total number of collisions of media	1
$n_{\varphi 15-\varphi 15}$	number of collisions between $\varphi$15 mm media	1
$n_{\varphi 15-\varphi 22}$	number of collisions between $\varphi$15 mm and $\varphi$22 mm media	1
$n_{\varphi 22-\varphi 22}$	number of collisions between $\varphi$22 mm media	1
$\overline{n}$	average total number of collisions	1
$N_t$	number of nodes	1
$\overline{T}$	average torque at different moments	N m
$T_i$	stirrer torque	N m
$N_t$	number of nodes	N m
$E_i$	total collision energy loss	J
$E_{\varphi 15-\varphi 15}$	collision energy loss between $\varphi$15 mm media	J
$E_{\varphi 15-\varphi 22}$	collision energy loss between $\varphi$15 mm and $\varphi$22 mm media	J
$E_{\varphi 22-\varphi 22}$	collision energy loss between $\varphi$22 mm media	J
$\overline{E}$	average total collision energy loss	J
m	mass	kg
v	velocity	m/s
w	angular velocity	rad/s
I	rotational inertia	kg m${}^2$
$F_{n,ji}$	normal forces between balls i and j	N
$F_{t,ij}$	tangential forces between balls i and j	N
g	gravity acceleration	m s${}^{-2}$
$R_i$	radius of ball i	m
t	time	s
${\delta }_n$	normal overlap of the two balls	m
${\delta }_t$	tangential overlap of the two balls	m
$v_{n,ij}$	normal velocities between the two balls	m/s
$v_{t,ij}$	tangential velocities between the two balls	m/s
${\mu }_{s,ij}$	static friction coefficient	−
$E^{*}$	equivalent elastic modulus	Pa
$R^{*}$	equivalent contact radius	m
$G^{*}$	equivalent shear modulus	Pa
$m^{*}$	equivalent mass of the two balls	kg
$E_k$	Young’s modulus	Pa
$m^{*}$	mass	kg
$u_k$	Poisson’s ratio of balls	−
H	cylinder height	mm
h	screw agitator height	mm
D	cylinder diameter	mm