• powder surface velocity;
  • dry powder;
  • excipient;
  • impeller speed;
  • PSV


An existing method to measure particle velocity is particle image velocimetry which requires presence of tracer materials. This method of contrast enhancement is not always applicable in an industrial setting. Therefore a method to assess the movement of small, structures has been introduced, called powder surface velocimetry (PSV). The principle of PSV is to follow the movement of small structures on the surface of the powder bed. The displacement of the structure is correlated with velocity. The rate of the blade of a blender was quantified to assess the validity of PSV. Next the powder surface velocity of lactose 100 M was measured by PSV and was found to be in line with expected values and flow regimes. © 2011 American Institute of Chemical Engineers AIChE J, 2012