Numerical Simulation of Mixing Processes in Two - Channel Flows

Recently, considerable interest has arisen in the numerical simulation of laminar and turbulent transport phenomena. More knowledge in this field is needed to improve predictions of heat and mass transfer processes in a variety of technical fields. In this work a new computationally efficient transport model is developed. It consists of partially parabolized time-dependent equations of motion, continuity, and concentration of nonconservative species. Pertinent equations are solved numerically for both laminar and turbulent flow. Results of calculations of laminar flow in the entry region of a parallel-plate channel agree well with the work of other authors. For turbulent flows, the system of equations is closed using either Prandtl's mixing-length hypothesis or a turbulence model describing the transport of kinetic energy of turbulence. Present calculations of a jet discharging into a coflowing stream correspond satisfactorily with numerical and experimental results of other investigators. The mixing part of the numerical model is verified using analytical solutions of simplified mixing processes and experimental results obtained in the Missouri River. An application of the transport model is made to study the case in which radioactive material from a nuclear facility is discharged into the Missouri River. The extent and the time history of the radioactive spill are calculated for two different discharge concepts and governing parameters are identified.