Inequalities for mixing processes

Abstract Four one-dimensional models which have been used to characterize surface mixed layer (ML) processes and the thermal structure are described. Although most any model can be calibrated to mimic surface water temperatures, it does not imply that the corresponding mixing processes are well described. Eddy diffusion or "K" models can exhibit this problem. If a ML model is to be useful for water quality applications, then it must be able to resolve storm events and, therefore, be able to simulate the ML depth, h, and its time rate of change, dh/dt. A general water quality model is derived from mass conservation principles to demonstrate how ML models can be used in a physically meaningful way to address water quality issues.

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An investigation of fine sediment mixing within free-flowing and surcharged manholes

Water Science & Technology ◽

10.2166/wst.1998.0052 ◽

1998 ◽

Vol 37 (1) ◽

pp. 215-222

Author(s):

I. Guymer ◽

R. O'Brien ◽

O. Mark ◽

P. Dennis

Keyword(s):

Dead Zone ◽

Laser Induced Fluorescence ◽

Fine Sediment ◽

Longitudinal Dispersion ◽

Qualitative Description ◽

Suspended Material ◽

Mixing Processes ◽

Future Developments ◽

Mixing Effects ◽

Sediment Mixing

Previous studies of the effects of manholes on longitudinal dispersion has concentrated on the spreading of solutes. This papers presents new data describing the influence of a surcharged and free-flowing manhole structure on the longitudinal dispersion of a fine suspended material. The effects of benching within the manhole structure are also illustrated. Laser Induced Fluorescence (LIF) techniques have been used to provide a qualitative description of the mixing processes present within a surcharged manhole. Nephelometric results have provided estimates of the parameters required to simulate the mixing effects using either increase in variance or aggregated dead zone techniques. A preliminary attempt at describing these observations using available software is discussed and recommendations for future developments are made.

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