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Full-Text Articles in Engineering
Density Currents In Circular Wastewater Treatment Tanks, David M. Laliberte
Density Currents In Circular Wastewater Treatment Tanks, David M. Laliberte
Dissertations and Theses
Deviations from ideal flow and settling occur in circular wastewater treatment tanks because of tank geometry, flow conditions, and density currents caused by variations in suspended solids concentration and temperature distributions. Thermally induced density currents were investigated in this study. Under winter, low flow conditions, measurements were made of vertical and radial temperature distributions in the circular chlorination tank at Lake Oswego, Or., and in the circular primary and secondary clarifiers at Bend, Or. Thermistor arrays were used to collect the data which exhibited both vertically well-mixed and a two-layer flow regime. Inlet geometry and suspended solids in the secondary …
Residual Circulation In Shallow Estuaries 2. Weakly Stratified And Partially Mixed, Narrow Estuaries, David A. Jay, J. Dungan Smith
Residual Circulation In Shallow Estuaries 2. Weakly Stratified And Partially Mixed, Narrow Estuaries, David A. Jay, J. Dungan Smith
Civil and Environmental Engineering Faculty Publications and Presentations
Long-wave theory is used herein to analyze circulation in weakly stratified and partially mixed estuaries. Unlike the highly stratified systems considered in part 1, the flows considered here have only a minimal tidal-frequency internal wave component. These estuaries may therefore be modeled as the sum of weakly interacting barotropic and baroclinic modes. The dominant factors driving the residual flow are finite amplitude barotropic effects in weakly stratified estuaries and a combination of barotropic effects and steady horizontal density gradient forcing in partially mixed estuaries. The dominant vertical exchange mechanism in the weakly stratified case is bottom boundary-induced turbulence, and that …
Residual Circulation In Shallow Estuaries 1. Highly Stratified, Narrow Estuaries, David A. Jay, J. Dungan Smith
Residual Circulation In Shallow Estuaries 1. Highly Stratified, Narrow Estuaries, David A. Jay, J. Dungan Smith
Civil and Environmental Engineering Faculty Publications and Presentations
Long-wave theory and simple turbulence closures have been used to show that three distinct types of circulation (highly stratified, weakly stratified, and partially mixed) arise in narrow, shallow estuaries from the finite amplitude of the tide and the interaction of stratification with vertical mixing. Each type has a different dominant process causing the vertical exchange of salt and fresh water on the flood, and each gives rise to a characteristic residual circulation. The tidal circulation in highly stratified shallow estuaries, described herein, is the result of a finite amplitude internal motion driven by the barotropic tide; shear instabilities at the …