124
CHAPTER 4. HYDRODYNAMIC MODELS
truly undistorted. This could be important, particularly
when scaling up the hydrodynamic parameters.
4.2.4 Short-Wave Model Thermal Similitude
Most models requiring thermal similitude concern discharge of heated water
that has been used to cool condensers at thermal power plants. Environmental impacts of thermal effluents discharged into coastal waters must be
assessed as part of a project’s overall feasibility, and properly conducted
physical models can provide useful information toward this assessment.
The physical processes involved in the injection, dispersion, and cooling
of heated water introduced into the coastal zone are varied and complex.
The main stages of thermal dispersion were quoted12 by Lavender and
Cowley (1975) as
12Originally attributed to Peter Ackers, 1969. “Modelling of Heated Water Discharges,” in Engineering Aspects of Thermal Pollution, ed. Parker and Krenkel, Vanderbilt University Press.
1. Turbulent entrainment at the efflux jet. Close to the outfall
the inertia of the jet is important, while density differences
between the heated and ambient water are not.
2. Buoyant rise of the jet if it is submerged. The trajectory
of the jet is dependent on initial inertia as well as the
buoyancy force due to density differences. Turbulence at
the plume boundary will initiate mixing.
3. Convective spreading of the effluent from an initial dilution
zone over the surface of the receiving water.
4. Mass transport of the effluent by ambient waves and currents.
5. Diffusion and dispersion due to wave- and current-induced
turbulence in the ambient waters.
6. Loss of heat by evaporative cooling at the surface.
Lavender and Cowley (1975) also noted that salinity variations, boundary
roughness, shear forces, and movement of bed material may be important
in some thermal dispersion studies.
Parker, et al. (1976) noted that the thermal dispersion problem can be
divided into three regions: the near field, where entrainment is important;
the joining region, where buoyancy, surface cooling and convection are important (along with entrainment); and the far field, where surface cooling,
convection, and dispersion are important.
CHAPTER 4. HYDRODYNAMIC MODELS
truly undistorted. This could be important, particularly
when scaling up the hydrodynamic parameters.
4.2.4 Short-Wave Model Thermal Similitude
Most models requiring thermal similitude concern discharge of heated water
that has been used to cool condensers at thermal power plants. Environmental impacts of thermal effluents discharged into coastal waters must be
assessed as part of a project’s overall feasibility, and properly conducted
physical models can provide useful information toward this assessment.
The physical processes involved in the injection, dispersion, and cooling
of heated water introduced into the coastal zone are varied and complex.
The main stages of thermal dispersion were quoted12 by Lavender and
Cowley (1975) as
12Originally attributed to Peter Ackers, 1969. “Modelling of Heated Water Discharges,” in Engineering Aspects of Thermal Pollution, ed. Parker and Krenkel, Vanderbilt University Press.
1. Turbulent entrainment at the efflux jet. Close to the outfall
the inertia of the jet is important, while density differences
between the heated and ambient water are not.
2. Buoyant rise of the jet if it is submerged. The trajectory
of the jet is dependent on initial inertia as well as the
buoyancy force due to density differences. Turbulence at
the plume boundary will initiate mixing.
3. Convective spreading of the effluent from an initial dilution
zone over the surface of the receiving water.
4. Mass transport of the effluent by ambient waves and currents.
5. Diffusion and dispersion due to wave- and current-induced
turbulence in the ambient waters.
6. Loss of heat by evaporative cooling at the surface.
Lavender and Cowley (1975) also noted that salinity variations, boundary
roughness, shear forces, and movement of bed material may be important
in some thermal dispersion studies.
Parker, et al. (1976) noted that the thermal dispersion problem can be
divided into three regions: the near field, where entrainment is important;
the joining region, where buoyancy, surface cooling and convection are important (along with entrainment); and the far field, where surface cooling,
convection, and dispersion are important.