Radial nonuniformity index (RNI) in fluidized beds and other multiphase flow systems

Jing Xu Zhu, Samwel V. Manyele

Research output: Journal PublicationArticlepeer-review

76 Citations (Scopus)


The radial nonuniformity index (RNI) is a new non-dimensional index recently devised to quantify the extent of radial variations of flow parameters in fluidized beds and other multiphase flow systems. The index, defined as the ratio of the standard deviation of the given flow parameter in the radial direction to the maximum practically possible standard deviation of that particular parameter, is shown to be an excellent measure of the radial flow structure. This index allows the use of a single value to summarize the radial variation of a given flow parameter. The higher the value of the RNI the less uniform is the flow, and vice versa. Using this technique, radial distributions of local solids concentration and particle velocities from different circulating fluidized bed systems (gas-solid and liquid-solid, upflow and downflow) were examined. It has been found that the RNI can be confidently related to the flow conditions in the circulating fluidized beds, and more insight understanding has been achieved.

Original languageEnglish
Pages (from-to)203-213
Number of pages11
JournalCanadian Journal of Chemical Engineering
Issue number2
Publication statusPublished - 2001
Externally publishedYes


  • Fluidized beds
  • Maximum standard deviation
  • Radial flow nonuniformity
  • Radial flow profile
  • Radial nonuniformity index

ASJC Scopus subject areas

  • Chemical Engineering (all)


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