A global method for coupling transport with chemistry in heterogeneous porous media

Modeling reactive transport in porous media, using a local chemical equilibrium assumption, leads to a system of advection-diffusion PDE's coupled with algebraic equations. When solving this coupled system, the algebraic equations have to be solved at each grid point for each chemical species and at each time step. This leads to a coupled non-linear system. In this paper a global solution approach that enables to keep the software codes for transport and chemistry distinct is proposed. The method applies the Newton-Krylov framework to the formulation for reactive transport used in operator splitting. The method is formulated in terms of total mobile and total fixed concentrations and uses the chemical solver as a black box, as it only requires that on be able to solve chemical equilibrium problems (and compute derivatives), without having to know the solution method. An additional advantage of the Newton-Krylov method is that the Jacobian is only needed as an operator in a Jacobian matrix times vector product. The proposed method is tested on the MoMaS reactive transport benchmark.Comment: Computational Geosciences (2009) http://www.springerlink.com/content/933p55085742m203/?p=db14bb8c399b49979ba8389a3cae1b0f&pi=1

NACA Technical Notes

Note presenting an investigation of the effect of cooling on boundary-layer transition in the steady flow of air in the entrance of a smooth round tube. The primary purpose was to investigate the practical possibilities of delaying the transition point, and thus increasing the transition Reynolds number, by cooling the laminar boundary layer in a gas. The results indicate that the effect of cooling on transition is not likely to be significant in any normal internal flow

NACA Technical Notes

Note presenting an experimental study of friction coefficients near the inlet of smooth, round tubes with bellmouth entrances. Four different combinations of approach section and bellmouth entry were used. Results regarding the apparent local friction coefficient, integrated friction coefficient, effect of induced turbulence, laminar inlet zone, developed friction coefficient, and application to discharge coefficients for rounded-entrance flow nozzles are provided