(399g) Fundamental Studies of Laminar Stagnation Flows and Design of Stagnation-Flow Reactors

This presentation is dedicated to the memory of Professor Robert Brodkey and will focus on fundamental studies of laminar stagnation flow patterns formed by (1) two symmetric counterflowing jets and (2) axisymmetric flows towards a rotating disc. Stagnation flows formed by counterflowing laminar jets are used in a variety of applications, including kinetic studies of diffusion flames, nanoparticle synthesis, microfluidic devices, and polymer processing. Stagnation flows towards rotating discs are commonly encountered in reactors used for vapor phase epitaxy of thin films of semiconductors for microelectronics applications and in analytical instruments used for electrochemical and kinetic studies. Understanding of the structure and stability of these flows is important for the optimal design and operation of process equipment that employ them. Isothermal laminar flows of Newtonian fluids in symmetric counterflowing arrangements exhibit interesting flow patterns above a critical Reynolds number that include time-periodic flows in planar jets and multiple-steady states in axisymmetric jets that can complicate the design of process equipment and devices that employ them [1]. Flow recirculation patterns in rotating-disc reactors used for metalorganic vapor phase epitaxy that are induced by natural convection, disc rotational rate or reactor geometry can have detrimental effects on film quality. Prediction of the onset of flow recirculation is important for optimizing reactor operation. Fundamental studies of the underlying flow patterns can be used to develop generalized flow maps based on dimensionless quantities (Reynolds number, rotational Reynolds number, and Grashof number) and that can guide the design and optimization of commercial rotating-disc reactors [2].

[1] R.P. Pawlowski, A. G. Salinger, J.N. Shadid, and T.J. Mountziaris, Bifurcation and stability analysis of laminar isothermal counterflowing jets, J. Fluid Mech. (2006), vol. 551, pp. 117–139.

[2] J. Cho and T.J. Mountziaris, Onset of Flow Recirculation in Vertical Rotating-Disc Chemical Vapor Deposition Reactors, AIChE J. (2013), vol. 59, pp. 3530–3538.