Analysis of laser-induced convection in unconfined fluids and in vertical cylinders

Laminar natural convection induced in fluids by absorption of energy from a vertical laser beam is analyzed for two different configurations. In the first configuration, the vertical beam propagates in an unconfined fluid, and is modeled as a line source of thermal energy. Ordinary differential equations are obtained by a similarity analysis of the axisymmetric boundary layer equations, and approximate solutions of them are obtained. In the second configuration, the beam propagates in a fluid confined in a tall, isothermal vertical cylinder, and is assumed to have a Gaussian radial distribution of intensity. An exact solution of the Navier-Stokes and thermal energy equations is obtained for the case of parallel flow. Representative numerical results are presented, and estimates are made of the parametric ranges of validity of the analyses.