The angle of repose under water is experimentally determined for a single particle on a fixed rough bed.

The effect of grain shape, size and sorting of the bed and ratio of particle diameter to average bed grain diameter are taken into account. An empirical equation is given for predicting angle of repose as a function of the above factors. The accuracy of fit of this equation is quite good. Several other conclusions drawn for the case of a single grain on a fixed rough bed are:

  • 1
    Angle of repose increases with decrease in size, departure from sphericity and increased angularity.
  • 2
    Angle of repose increase with decrease in sorting.
  • 3
    A single angle of repose for sand size grains is not valid. Variation ranges from nearly 90° to less than 20°, depending on the values of the factors given above.