Yahaya, J.D. et al. 2026. Unsteady Darcy-Brinkman Axial Flow in a Porous Concentric Annulus: A Semi-Analytical Riemann-Sum Approach. FUDMA JOURNAL OF SCIENCES. 10, 10 (Jun. 2026), 269–275. DOI:https://doi.org/10.33003/fjs-2026-1010-5506.