Shijie Liu

A model for particle settling velocities in polydisperse suspensions is proposed alongside normalized particle self and interaction mobilities. The model predictions are compared with other models (Davis and Gecol, 1994; and Al‐Naafa and Selim, 1989), as well as published experimental data. A general agreement was found between the current model and the existing data for binary dispersed particle systems except for one case where Φ_L is fixed. For ternary dispersed particle systems, predictions from both the A‐S model and the current model agree well with the existing data. With the improved sedimentation coefficients, the D‐G model also produces satisfactory results.

This study was carried out to seek a suitable model to describe flow through orifices. The model of developing flow through short ducts was found to be adequate. There were two free parameters in the model equation involving the normalized pressure drop and Reynolds number. Experiments were performed using two Plexiglas tanks separated by an orifice. The liquid level height variation with time was recorded. A unique parametric estimation technique was used to determine the two free parameters from the dynamic liquid level data. It was found that direct use of the experimental data (liquid level heights) is the best option in correlating the experimental data with the model. The correlation fits well with the present and literature experimental data quite well. It was found that the variation of the pressure drop with the flow rate is linear when the flow is weak, where the orifice Reynolds number is less 10. When the flow is strong, the ratio of the pressure drop to the flow rate becomes linearly related to the flow rate. These two limits are identical to those for flow in porous media.