Table 3.

Surface roughness profile parameters.

Parameter	Straight	Curved	Spiral	Helical
(All Values Are in $\mathsf{\mu }$m)	Channel	Channel	Channel	Channel
Roughness Average, $R_a$	0.598	1.817	2.170	2.907
Average Maximum Height of the Profile, $R_z$	4.013	11.334	13.343	16.396
Maximum Height of the Profile, $R_t$	4.888	13.146	16.740	21.784
RMS Roughness, $R_q$	0.794	2.241	2.713	3.570
Maximum Profile Peak Height, $R_p$	1.147	6.071	5.906	6.575
Kurtosis, $R_{ku}$	4.787	2.712	3.049	3.876
Skewness, $R_{sk}$	1.137	0.150	0.524	0.750