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Updated: May 16, 2026
11:51
Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions
Published on: February 22, 2018
Verification of equations for incipient motion studies for a rigid rectangular channel.
Charles Hin Joo Bong1, Tze Liang Lau, Aminuddin Ab Ghani
1River Engineering and Urban Drainage Research Centre (REDAC), Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300 Nibong Tebal, Penang, Malaysia. bhjcharles@feng.unimas.my
Summary
This study tested equations for incipient motion in rectangular channels. A new equation incorporating sediment deposit thickness improved prediction accuracy for sediment transport.
Area of Science:
- * Fluid Mechanics
- * Sediment Transport
- * Open Channel Flow
Background:
- * Existing equations for incipient motion in rigid rectangular channels require verification.
- * Sediment deposit thickness is a critical factor influencing incipient motion dynamics.
- * Previous models may not fully account for the impact of sediment layer depth.
Purpose of the Study:
- * To validate established incipient motion equations (Novak & Nalluri, El-Zaemey) against experimental data.
- * To investigate the influence of sediment deposit thickness on critical velocity predictions.
- * To develop an improved equation for incipient motion that incorporates sediment depth.
Main Methods:
- * Experimental data collection from a rectangular flume (0.3m and 0.6m widths).
- * Comparison of experimental critical velocity with predictions from Novak & Nalluri and El-Zaemey equations.
- * Analysis using the Shields Diagram to visualize the effect of sediment deposit thickness.
- * Development and validation of a new predictive equation.
Main Results:
- * El-Zaemey's equation showed better initial agreement (average discrepancy ratio 1.06) than Novak & Nalluri (0.87).
- * Accuracy of El-Zaemey's equation decreased with increasing sediment deposit thickness.
- * Shields Diagram analysis confirmed that thicker deposits increase dimensionless shear stress (θ).
- * The newly proposed equation, including sediment thickness, yielded improved predictions (average discrepancy ratio 1.02).
Conclusions:
- * Existing equations have limitations, particularly with thicker sediment deposits.
- * Sediment deposit thickness significantly impacts incipient motion and requires explicit consideration.
- * The new equation offers a more accurate approach for predicting incipient motion in rectangular channels with varying sediment depths.
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