This document describes a CFD conceptual analysis of an oxygen diffuser cup. The analysis examines the effects of breathing with an oxygen diffuser cup by simulating the rise in oxygen levels resulting from the cup. Key assumptions include steady state, non-compressible flow and rigid bodies. Boundary conditions include an inhalation oxygen flow of 0.01 L/s from the diffuser cup. Graphs of simulation results show velocity vectors and the increase in oxygen mass fraction within the breathing area due to the diffuser cup during inhalation.