Observations of "granular jump" in the pneumatic conveying system

A.J. Jaworski, T. Dyakowski

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


This paper presents a preliminary study of a previously unreported phenomenon of the “gas driven granular jump”, observed in the gas–solids flow within the pneumatic conveying system. From the phenomenological point of view, it resembles the already known processes such as hydraulic jumps in shallow water or granular jumps in granular flows in chutes or avalanches (although it seems most appropriate to explain it by analogy to a propagating granular bore). Clearly, unlike in classical phenomena of this type, the flow itself is driven by the aerodynamic forces related to the gas flow and the behaviour of the front of the “jump” is modified significantly by their presence. A series of high-speed camera visualisations are presented, which focus on this unusual behaviour of the flow on the border-line between cluster and stratified flow regimes in a horizontal pipe. Some similarities are drawn between the observed phenomenon and the broader class of problems exhibiting transition between super- and sub-critical flows. The fluid dynamical aspects and possible mechanisms behind the new phenomenon are discussed and the results obtained are compared quantitatively with simple theoretical models.
Original languageEnglish
Pages (from-to)877-885
Number of pages9
JournalExperimental Thermal and Fluid Science
Issue number8
Early online date27 Oct 2006
Publication statusPublished - Aug 2007
Externally publishedYes


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