Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The problem of waste heat discharge into natural bodies of water is one of the environmental problems that has received considerable attention in recent years. The scope of most of the previous investigations has been limited to summer flow conditions and did not address the problem of waste heat discharge in cold climate regions. This thesis is concerned with the problem of a thermal discharge in a channel in the range of temperatures encountered in practice, including temperatures anticipated in cold climate regions.;More specifically, this study was conducted to: (i) develop numerical models of surface and bottom discharges in a channel based on the non-linear equation of state; (ii) verify experimentally the predictions of the non-linear models for different ambient temperatures; (iii) investigate experimentally surface and bottom thermal plumes at ambient temperatures less than 4{dollar}\sp\circ{dollar}C; and finally, (iv) quantify the Reynolds number effect on the scale modeling of surface thermal plumes.;Non-linear models for surface and bottom thermal discharges were developed based on the equations of mass, momentum and temperature transport. The non-linear equation of state of water was shown to have an important effect on the behaviour of thermal plumes. The experimental results confirmed this finding and were in very good agreement with the predictions of the models. The error of applying a linear equation of state in modeling thermal plumes was found to increase as the ambient temperature approached 4{dollar}\sp\circ{dollar}C.;When the ambient water temperature was less than 4{dollar}\sp\circ{dollar}C the thermal plume was effected by the reversing of buoyancy. The surface thermal plume became unstable within a short distance from the outlet and sank towards the bottom. The bottom thermal plume, under similar conditions, was initially unstable then became stable and remained attached to the bottom.;The turbulent structure of thermal plumes was examined, to study the effect of the Reynolds number on the temperature field of thermal plumes. The Reynolds number was found to have little effect on the global entrainment characteristics and considerable effect on the internal mixing characteristics, particularly, for Reynolds numbers less than about 7000.



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