| The thesis presents accurate numerical solutions of the full two dimensional governing equations for steady and unsteady laminar/laminar internal condensing flows of pure vapor inside a vertical tube, a channel, and for external flows for the well known Nusselt problem.; The film condensation is on the inside wall of a tube or one of the walls of a channel (the lower wall in case of a downward sloping channel). Computations find that exit condition specifications are important and are able to characterize the flows' sensitivity or insensitivity to the exit condition (which, in turn, depends upon the flow downstream of the condenser). If well defined natural steady/quasi-steady flows exist in the absence of a specified exit condition---as is shown to be the case for gravity dominated or strong shear dominated condensate---the computations are able to predict the "attracting" solution and the natural "attracting" exit condition and any point of transition (from to wavy behavior) that may exist within this zone.; The external flow problem (Nusselt problem), solved accurately up to film Reynolds number of 60 (Redelta ≤ 60), establishes various features of the well known steady solution and reveals the interesting phenomena of stability, instability and non-linear wave effects. It is shown that intrinsic flow instabilities cause the wave effects to grow over the well known experiments-based range of Redelta ≥ 30.; The wave effects due to film flow's sensitivity to ever present minuscule transverse vibrations of the condensing surface are also described for all cases. The results suggest some ways of choosing wall noise---through suitable actuators---that can enhance or dampen wave fluctuations and thus increase or decrease heat transfer rates over the laminar-to-turbulent transition zone. |
