Taylor-Couette flow of concentrated non-colloidal suspensions with a rotating inner cylinder and a stationary outer one is numerically investigated. We consider suspensions of the bulk particle volume fraction ϕb = 0.2, 0.3 with the ratio of an annular gap to the particle radius ϵ = 60 confined in a cylindrical annulus of the radius ratio (i.e., the ratio of inner and outer diameters) η = 0.877. Numerical simulations are performed by applying the suspension-balance model and rheological constitutive laws. To observe flow patterns caused by suspended particles, the Reynolds number of the suspension, based on the bulk particle volume fraction and the rotating velocity of the inner cylinder, is varied up to 180. At a high Reynold number, modulated patterns undiscovered in the flow of a semi-dilute suspension emerge beyond a wavy vortex flow. Thus, a transition occurs from the circular Couette flow (CCF) via ribbons (RIB), spiral vortex flow (SVF), wavy spiral vortex flow (WSVF), wavy vortex flow (WVF), and modulated wavy vortex flow (MWVF) for the concentrated suspensions. Moreover, friction and torque coefficients for suspensions are estimated. It turns out that suspended particles significantly enhance the torque on the inner cylinder while reducing the friction coefficient and the pseudo Nusselt number. In particular, the coefficients are reduced in the flow of more dense suspensions (Kang et al. (2023)).