AbstractThis study presents a numerical analysis of a model for the coupled mechanisms of transport of natural convection, thermophoresis, and double‐diffusive heat and mass transfer of a fluid holding suspended particles in an infinite parallel‐plated channel. The governing equations in an unsteady state are nondimensionalized and solved by subdivisions of the finite difference method. The simulations of the numerical algorithms are verified by analytic results. Thermal and mass transfer characteristics of parameters like time are displayed graphically. The findings in this study suggest that increases in Schmidt number accentuate the effect of thermophoresis hence is the effective thermophoretic coefficient agreeing with Magyari. At steady‐state, there is an increase in skin friction at the hot wall when the thermophoretic coefficient was in the range , alerting when the walls of the channel are in danger from the heat. The gradient of concentration of particles at the hot wall, when in steady‐state remains unity for every value of thermophoretic coefficient and at the cold wall is constantly . This study suggests that the steadiness of a fluid and conduction/convection resistances within and outside boundaries may influence thermophoretic effect. This study offers possibilities and supports the developments in thermophoretic cells used in the manipulation of particles for biochemical and medical research.