Improved drag coefficient and settling velocity for carbonate sands

Area of Science:

• Coastal geology
• Oceanography
• Sediment dynamics

Background:

• Sediment transport equations are vital for coastal change modeling.
• Existing models, often based on siliciclastic sands, are applied to carbonate sands despite differing properties.
• Effective management of carbonate sand transport is essential for coral reef ecosystems.

Purpose of the Study:

• To develop a novel approach for estimating the drag coefficient of carbonate sands.
• To account for both friction and pressure in drag coefficient calculations.
• To improve the accuracy of sediment transport models for carbonate environments.

Main Methods:

• Developed a new method to calculate drag coefficients for carbonate sands.
• Incorporated both frictional and pressure components into the drag coefficient estimation.
• Analyzed a database of carbonate sand settling velocities.

Main Results:

• The new drag coefficient method explains the wide variability in carbonate sand settling velocities (0.025–0.364 m/s).
• Small variations in settling velocity significantly impact sediment transport calculations.
• The findings highlight limitations in current numerical models.

Conclusions:

• A refined drag coefficient calculation is necessary for accurate carbonate sand transport modeling.
• Updated numerical models are required to incorporate these new findings.
• This research supports better management of coastal and reef sedimentary features.