Determining drag coefficient and terminal velocity of garlic (Allium sativum L.) in vertical wind tunnel

Abstract

The terminal velocity ,drag coefficient and Reynold's number of two common types of garlic (Allium sativum L.) cloves (white and pink) in Iran were determined by the mean of the air velocities required to suspend the garlic cloves in an air stream. In order to calculate the drag coefficient of garlic cloves, three dimensions and projected area of seventy five of each sample were measured individually by using machine vision method. Particle densities of cloves were measured by using a gas comparison multipycnometer. The terminal velocities of cloves were measured at a moisture content range from 34.9 to 56.7% (w.b.). Analysis variance (ANOVA) showed that the terminal velocity for both types of garlic cloves were significantly affected by moisture content (P<0.01). The relationship between values of terminal velocity and moisture content were expressed by linear equations. White garlic cloves had the lowest value of terminal velocity of 9.82 m/s at 34.9% (w.b.); the maximum terminal velocity value was 16.66 m/s at 56.7% (w.b.) for pink cloves. The mean values of drag coefficient and Reynold's number at initial moisture content 42.4% (w.b.) were 1.167 and 17200 for white garlic cloves, respectively; the corresponding values for pink garlic cloves were 1.036 and 16610, respectively.