Newtonian flow past a hollow frustum in vertical and inclined plane: An experimental observation for terminal velocity and drag coefficient

Abstract

This work included the experimental studies of the Newtonian fluid flow over hollow frustum both in the normal and inclined channel. It encompasses terminal velocity and drag coefficient, CD data for 0.13 ≤ Re ≤ 8.41, 0.19 ≤ do/D ≤ 0.33, 0.22 ≤ di/do ≤ 0.83 and 40° ≤ θ ≤ 90o. The effect of inner diameter to outer diameter ratio, di/do and the outer diameter to the flow channel diameter ratio, do/D on terminal velocity is reported for the specified range of angle of inclination, θ for several hollow frustums in a series of high viscous Newtonian fluids. The terminal velocity shows an increasing trend with increasing and decreasing do/D and di/do ratios, respectively. The terminal velocity also increases with increasing the angle of inclination, θ of the flow channel. Predictive equations are developed for the estimation of CD as a combined function of Re, di/do, do/D and θ. The statistical sensitivity analysis shows a large variation of the drag coefficient of the hollow frustum with the Reynolds number than with di/do and do/D ratios. The dependency of CDRe term on the fluid viscosity and θ are expressed in terms of the developed correlations. Linear variation of CD with 1/Re confirms that flow regime is laminar in the present study. The experimental drag coefficients are then predicted excellently through numerical approximation using Reynolds Stress Model (RSM) available in Ansys-15.