$\sigma$	cavitation number
$Re$	Reynolds number
$\alpha$	angle of attack of the hydrofoil or bluff body
L	length of the attached vapor–gas cavity
C	chord length of the hydrofoil or bluff body
$p_{\infty }$	characteristic pressure of the incoming flow
$p_v$	saturated vapor pressure
$\rho$	liquid density
$U_{\infty }$	bulk/free-stream flow velocity
Q	volumetric flow rate
$I_k$	k-th instantaneous image/frame in the video sequence
N	number of frames in the video sequence
$I_{\mathrm{aver}}$	temporal-average image used as the background image
$I_{\mathrm{th}}$	thresholded image containing pixels above the selected intensity threshold
$I_c$	hydrofoil-contour image obtained by edge detection
$I_{\mathrm{bwl}}$	binary mask of residual pixel clusters selected by area filtering along the hydrofoil contour
$I_{\mathrm{rez},k}$	k-th processed image after subtraction/removal of the bluff-body image
$th$	dimensionless threshold correction coefficient used for image binarization
$\lambda$	longitudinal size of the continuous white region in a binarized image, px
$ϵ$	the friction coefficient determined using the Blasius equation
$l_i$	instantaneous attached-cavity length in the i-th frame
$l_{\mathrm{avg}}$	time-averaged attached-cavity length over a video sequence
px	pixel unit used for image-coordinate measurements
$O_x$, $O_y$	image-coordinate axes used for boundary search