Effect of hydrodynamic characteristics on reaeration process

Area of Science:

• Environmental Engineering
• Fluid Dynamics
• Water Quality

Background:

• Reaeration is crucial for maintaining dissolved oxygen (DO) in natural waters.
• Accurate interfacial mass transfer coefficients are needed for water quality modeling.
• Understanding turbulence effects on reaeration is essential for predicting oxygen levels.

Purpose of the Study:

• To determine interfacial mass transfer coefficients of dissolved oxygen (DO) during flume reaeration.
• To investigate the relationship between flow characteristics and DO transfer.
• To develop and validate a predictive expression for the interfacial mass transfer coefficient.

Main Methods:

• Utilized the equilibrium-perturb technique in a flume reaeration experiment.
• Applied oxygen-flux theory to calculate mass transfer coefficients.
• Employed numerical simulation to analyze turbulence characteristics of the flow field.

Main Results:

• Interfacial mass transfer coefficients for DO were successfully obtained.
• An expression relating the interfacial mass transfer coefficient to velocity and turbulence kinetic energy was established.
• The developed expression was validated against experimental data from various cases.

Conclusions:

• The equilibrium-perturb technique and oxygen-flux theory effectively quantified DO mass transfer.
• Flow velocity and turbulence kinetic energy are key parameters influencing interfacial mass transfer.
• The derived expression provides a reliable method for predicting DO mass transfer coefficients in similar flow conditions.