Transient helium jet expansion into stagnant air in relation to laser drilling

Transient helium jet expansion into a stagnant air environment is modelled to resemble the laser vapour ejection from the cavity during the drilling process. As the metal vapour properties are not known, helium is employed while the previously measured jet inlet velocity profiles are introduced in the simulations. A numerical scheme employing a control volume approach is used to discretize the governing equations of flow. The predictions are validated through a case study associated with an incompressible transient jet flow. It is found that the jet inlet profile influences considerably the self-similar behaviour of the jet. Moreover, the jet expands radially in the early period while as time progresses, the axial penetration of the jet becomes high.