In situ observations of interaction between particulate agglomerates and an advancing planar solid liquid interface: microgravity experiments

Results are reported of directional solidification experiments on particula te agglomerate pushing and engulfment by a planar solid/liquid (s/l) interf ace. These experiments were conducted on the Space Shuttle Columbia during the United States Microgravity Payload 4 (USMP-4) Mission. It was found tha t the pushing to engulfment transition velocity, V-cr, for agglomerates dep ends not only on their effective size but also their orientation with respe ct to the s/l interface. The analytical model for predicting V-er of a sing le particle was subsequently enhanced to predict V-er, of the agglomerates by considering their shape factor and orientation. (C) 1999 Elsevier Scienc e B.V. All rights reserved.