Figure 5. Sample images of spherical LDPE particles fluidization with a superficial gas velocity of (a) 1.4Umf, (b) 2.0 Umf,(c) 3.0 Umf, (d) 3.4 Umf, and overlay of 500 images of (e) 3.0 Umf and (f) 3.4 Umfcases with the red dashed rectangle showing the region of the particle fountain.