Title: Advancing drag coefficient correlations for non-spherical particles in power-law fluids

Authors: Can Polat

Addresses: Petroleum and Natural Gas Engineering Department, Izmir Katip Celebi University, Cigli Main Campus, Science and Engineering Building, 35620, Cigli, Izmir, Turkey

Abstract: This study addresses the critical challenge of predicting the settling velocity of non-spherical particles in non-Newtonian fluids. Two established correlations between drag coefficient and particle Reynolds number were refined to enhance their applicability to non-spherical particles in power-law fluids. A systematic analysis of model coefficients across varying particle sphericities revealed the necessity of quantifying the coefficients with particle shape. By incorporating sphericity and optimising model parameters using experimental data, the complex interplay between drag coefficient, particle Reynolds number, and particle shape is captured, demonstrating improved flexibility at low particle Reynolds numbers and accurate representation of upward concavity observed at high particle Reynolds numbers. These improvements are reflected as a decrease in mean relative errors over a wide range of particle Reynolds numbers and sphericities, and in the predictive capability demonstrated in model validation tests. [Received: February 15, 2025; Accepted: May 31, 2025]

Keywords: settling velocity; drag coefficient; particle Reynolds number; power-law fluids; non-spherical particles.

DOI: 10.1504/IJOGCT.2026.153754

International Journal of Oil, Gas and Coal Technology, 2026 Vol.39 No.4, pp.435 - 457

Received: 10 Feb 2025
Accepted: 31 May 2025
Published online: 26 May 2026 *

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