The Investigation of the Riemann-Liouville Fractional Operator on Natural Convective Fluid Flow in a Vertical Cylindrical Material with Variable Viscosity. International Journal of Development Mathematics (IJDM), [S. l.], v. 3, n. 2, p. 140–153, 2026. DOI: 10.62054/ijdm/0302.10. Disponível em: https://ijdm.org.ng/index.php/Journals/article/view/342.. Acesso em: 21 sep. 2026.