VMFL042

VMFL042
Turbulent Mixing of Two Streams with Different Densities

Overview

Reference

R.E. Uittenbogaard. “Stably Stratified Mixing Layer”. Data Report for the 14th meeting of the IAHR Working Group on Refined Flow Modeling. 1989.

R.E. Uittenbogaard. “The Importance of Internal Waves for Mixing in a Stratified Estaurine Tidal Flow”. Manuscript, Delft University of Technology, 1995.

Solver Ansys Fluent, Ansys CFX

Physics/Models SST model, mixing layer, density difference, buoyancy

Input File

VMFL042_mixing.cas for Ansys Fluent

saline-mixing_layer.def for Ansys CFX

Project Files Link to Project Files Download Page

Test Case

Mixing of two turbulent streams of fresh water and saline water is modeled. The two streams are parallel at the inlet and mixing proceeds downstream.

Figure 107: Flow Domain

Material Properties	Geometry	Boundary Conditions
Density of fresh water: 1015 kg/m³ Density of saline water: 1030 kg/m³ Mixture kinematic diffusivity: 1 X 10^-9 m²/s	Length of the mixing duct = 40 m	Fresh water inlet velocity = 0.52 m/s Salt water inlet velocity = 0.32 m/s

Material Properties

Geometry

Boundary Conditions

Density of fresh water: 1015 kg/m³

Density of saline water: 1030 kg/m³

Mixture kinematic diffusivity:

1 X 10^-9 m²/s

Length of the mixing duct = 40 m

Fresh water inlet velocity = 0.52 m/s

Salt water inlet velocity = 0.32 m/s

Analysis Assumptions and Modeling Notes

The flow is steady. SST model is used. Buoyancy turbulence production option is used.

Results Comparison for Ansys Fluent

Figure 108: Comparison of Mass Fraction of Salt Water Across the Mixing Layer at x = 10m

Results Comparison for Ansys CFX

Figure 109: Comparison of Mass Fraction of Salt Water Across the Mixing Layer at x = 10m