This paper presents the results of the application of a computational fluid dynamics computer program to the simulation of cold and plasma flows in circuit-breakers. The underlying physical model is based on the axisymmetric form of the conservation equations which are coupled with an arc model including ohmic heating and radiative exchanges of energy in the fluid. Various cases are computed, ranging from steady cold flow to unsteady arc-flow interaction. A good agreement has been found between the computed solutions and the available experimental data, demonstrating a great potential of these tools for circuit-breaker design and analysis in the future.