Parameter

Significance

Observation

Centre/core region

Wall region

Mean

Gives an average distribution of the local solid concentration

Low values with regular flat profiles

Higher values, increase towards the wall

Standard Deviation

A measure of dispersion or fluctuation of solid concentration

Low values with relatively flat profiles

Higher values towards the wall

Skewness

Measures the symmetrical properties or degree of asymmetry of PDF around the mean

Higher and relatively flat profiles

Decrease towards the wall with irregular profiles

Kurtosis

Indicates the tendency of the PDF to be peaked

Higher values and generally flat profiles

Lower, slightly decreases towards the wall

Intermittent Index

Shows the extent of gas-solid fluctuations or gas-solid suspension flow segregation

Relatively higher/lower values and regular flat profiles

Irregular profiles, Slightly increase towards the wall

Coefficient of Variation

A measure of relative dispersion of a distribution. It indicates variability or scattering tendency

Relatively higher and regular profiles

Decreases towards the wall

Average Absolute Deviation

Estimates the width of data around the average values

Constant, higher or lower values with regular profiles

Irregular profiles, relatively increasing/decreasing towards wall

Probability Density Function

Indicates the distribution property of solid concentration

Tall and narrow left peak with longer tails to the right

Single or double peaks with tails towards the right