CORMIX Navigation Bar Home FAQ About CORMIX Software Applications Methodology References Model Validations Benchmark Technical Support Site Registration Downloads Upgrades Request Unlock Codes Order/Purchase Training Mixing Gallery New Developments Feedback Glossary Search  

Mixing Zone Processes in Lakes

The first step towards specifying ambient conditions in a lake is to determine whether the receiving water body should be considered "bounded" or "unbounded."

It is usually necessary to have access to cross-sectional diagrams of the water body. These should show the area normal to the ambient flow direction at the discharge site and at locations further downstream.

These cross-sections should then be schematized into equivalent rectangular areas normal to the flow.

The scematized cross-sections should preserve the effect of boundary interaction on the discharge flow.

Regulatory mixing zones in lakes may occur in the near-field or in the far-field after boundary interaction occurs.

Many lakes have very small or zero ambient velocity. In this case, steady-state mixing zone analysis is only possible for the near-field.

Furthermore, there is no far-field mixing because there is no ambient velocity field sufficient to carry away discharge material.

Mixing behavior is therefore dependent on local geometry.

Design and Modeling of Lake Wastewater Disposal Systems

Proper outfall siting and design is required for efficient wastewater treatment by utilization of the natural assimilative capacity of lakes.

Designs which trap flow in internal density current layers may be particularly advisable to avoid layers with both high nutrients and available light.

Also multiport diffusers which do not cause acceleration zones generally are desirable in lakes where diffuser-induced currents would be undesirable.

The CORMIX - GT advanced tools CorSens, CorVue, and CorSpy can assist the analyst in mixing zone analysis for outfall design specification.

Density Current Formationin Lake Cayuga
A density current front is formed from a warm tributary mixing zone in a cold lake Cayuga in Ithaca, NY.

A brine discharge into Onondaga Lake
A brine discharge into Onondaga Lake results in a plunging density current.

A buoyant jet is trapped by a stratified ambient.
A buoyant jet is trapped by a stratified ambient without crossflow (Source: Fan, CIT).

A CorVue visualization of CORMIX classification H3-A4
A CorVue visualization of CORMIX classification H3A4 showing i) near-field dynamic attachment with buoyant lift-off ii) subsequent flow trapping by stratified-crossflow ambient boundary interaction, and iii) density current formation with upstream spreading and stagnation point.