Foreword

<p dir="ltr">This Special Issue in memory of Professor Alvin W. Nienow contains a number of contributions and is a result of joint efforts from his past PhD students, collaborators and colleagues with whom he worked closely on various projects, courses and initiatives. Alvin’s research career, which started at UCL on fluidisation, crystallisation, and dissolution, spread to various single and multiphase mixing applications. After moving to the University of Birmingham to take up a Chair at the Department of Chemical Engineering on 1 April 1980, he continued with his research on fluidisation as well as fluid mixing processes in stirred tanks, with more emphasis on the latter and a particular focus on bioprocesses/bioproducts. His interest in the field and beyond is well documented by his own words in a recorded presentation he gave at UCL in 2021:<br><br>(Cont.)</p>