Recently, a method to achieve a natural hot-ion mode was suggested by utilizing ion viscous heating in a rotating plasma with a fixed boundary. We explore the steady-state solution to the Braginskii equations and find the parameter regime in which a significant temperature difference between ions and electrons can be sustained in a driven steady state. The threshold for this effect occurs at [Formula: see text]. An analytic, leading order low flow solution is obtained, and a numerical, moderate Mach number [Formula: see text] is investigated. The limitation is found to be at moderate Mach numbers.