| A new description of the interfacial heat and mass transfer process at the interface is described for high Schmidt number. The model is based on the concepts of, bursting period, horse shoe structure, and the energy spectrum of the turbulent boundary layer. It has been emphasized that the part of the turbulent energy spectrum which is responsible for the viscous dissipation, Fig 1A, is only responsible for the driving force for the transport process. The cut-off point on the spectrum was taken as the Kolmogoroff wave number. Based on this concept of energy spectra, a non-dimensional time period, which is defined as the time taken by the viscous sublayer to develop at the interface, is developed. In order to select the form of energy spectra, two different expressions were considered for the development of the model. In principle, the energy spectral function, for a given system can be developed from the first principle, i.e., from the Navier Stokes equation.;In order to follow the mechanism of transport process, a hydrodynamical model for the transport process is developed which is based on the three layer concept of Levich. This model provides expression exclusively for the buffer layer, turbulent core layer, and the average of the two, respectively. On comparing the experimental results with these gauges, it allows one to decipher the mechanism involved in the transport process. All these models developed on the basis of spectral theory and hydrodynamic theory, are applied to study the heat and mass transfer process in the case of flow in a pipe, stirred tank, packed and fluidized beds, etc. To make the model more general, expressions are developed which are applicable to both Newtonian and non-Newtonian fluids. A surface renewal model approach to the mass transfer, based on the concepts of non-dimensional time period, is then applied to the mass transfer from a suspended sphere in different fluid flow conditions. At the end, the role of mixing length and eddy viscosity at the interfacial mass transport are also investigated. |
