Shapes and Rise Velocities of Single Slugs

The slugs may appear in different forms. As shown in Fig. 9.21, Type (a) is the round-nosed slug, which occurs in systems of fine particles Type (b) is the wall slug (also known as the half slug), which takes place in beds with rough walls, large dp/D ratios, 

The rise velocity of a single isolated Type (a) slug can be given by [Hovmand and Davidson, 1971] 

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