Beschreibung:
<jats:title>Abstract</jats:title><jats:p>By employing the theory of propagation of columnar disturbance, general criteria for selective withdrawal in sedimentation basins are derived. The stratified fluid is assumed to be two‐layered with different density distribution in each layer. The effects of a free surface are also included in the analysis, but the viscosity is neglected as in most other studies of stratified flow behavior. The criteria for different density profiles are established in terms of the densimetric Froude number. If the actual densimetric Froude number is smaller than its critical value, selective withdrawal will occur. Comparison of the theoretical results with the experimental data obtained by Bohan and Grace [<jats:italic>1973</jats:italic>] <jats:italic>indicate an excellent agreement as long as the thickness of the bottom layer, s, is small compared to that of the top layer. Results obtained by assuming rigid upper boundary instead of free surface are also compared with the results derived in this paper. For weak stratification and small values of s they show excellent agreement. As s increases for strong stratification, the effect of free surface will become increasingly pronounced</jats:italic>.</jats:p>