The specularity coefficient is a key parameter for the Johnson and Jackson boundary conditions used in a two-fluid model (TFM), but it is experimentally unmeasurable. This work proposes a semianalytical and flow-dependent model for the specularity coefficient based on measurable particle properties and the data of Louge [Louge. Phys. Fluids, 1994, 6, 2253–2269]. Through TFM simulations, the model was tested in a granular Couette flow, a spouted bed, and a circulating fluidized bed riser. A discrete particle model (DPM) simulation of the Couette flow was also performed for comparison. It was found that the TFM results of the present model agreed with the DPM results and experimental data and thus justified the potential further applications of the model. Moreover, the parameter studies indicated that the friction coefficient between particle and wall was crucial to the present model.