Mixer Vessel, 2D

¶ MixerVesselAMI2D

Summary of the case, Mixer Vessel, 2D
Item Value/Name
Mesh Block mesh
Flow type transient
2 incompressible (water and oil)
Fluids state isothermal
immiscible
Solver multiphaseInterDyMFoam
Using VOF based interface capturing approach

1. Pre-processing

See the layout of the mixer here.

2. Settings

Physical parameters, Mixer Vessel, 2D
Item Value/Name
Density (ρ) [kg/m3] water: 1000
oil: 500
Kinematic viscosity (ν) [m2/s] water: 1e-6
oil: 1e-6
Interfacial tension (σ) [N/m] water – oil: 0.07
Rotation of the rotator (ω) [rads/s] 6.2832
Force of gravity (g) [m/s2] Case 1: (0, -9.8, 0)
Case 2: (0, 0, 0)
Case 1: Placement of water and oil fits to the natural state under gravity. Red: oil, blue: water.
Case 2: Under zero gravity, the arrangement of the oil in water (or vise versa) is possible, if taking an appropriate injection method. Red: oil, blue: water.

3. Simulation

Simulation, Mixer Vessel, 2D
Item Value/Name
Simulation time [s] 5
Time step [s] 1e-5
Note: The time step (ΔT or deltaT) is determined after preliminary survey for acceptable Courant number (C0) which is set to C0≤Cmax≤0.5.

4. Post-processing

Case 1
Case 2

The whitish phase fraction shows a mixture of approximately equal rates of water and oil. In Case 1, the whitish phase fraction is distributed unevenly in the mixer. On the other hand, in Case 2, the whitish phase fraction is distributed much evenly compared to Case 1 in the mixier.

5. Analysis

5.1 Improvements

Rotation of the rotator: The animation above is the case that the rotation of the rotato increased, i.e. ω(angular velocity)=1.5×default value(6.2832)=9.4248 [rads/s]. A quantitative analysis, e.g. amount of cell whose phase fraction is about 50%-water and 50%-oil should be plotted over time for this case and the previous case, is needed for comparison.

5.2 Implementation as Mechanical Emulsification

Dam Break, 4 phases

¶ Dambreak_4phases

Summary of the case, Dam Break, 4 phases
Item Value/Name
Mesh Block with grading mesh
Flow type transient
4 incompressible (air, oil, water and mercury)
Fluids state isothermal
immiscible
Solver multiphaseInterFoam

1. Pre-Processing

Block and grading mesh for the container. The unit is metre.

2. Settings

In the following figure, no inter-cellular iterlation is applied and thus each cell shows the calculated phase fraction for each fluid.

Initial setting of the fluids behind the invisible membrane. The colours denote the phase fraction of each fluid.

3. Simulation

It should be noticed that the colour of interfacial cells, e.g. yellow-orange colour (as the attribute of mercury's 100% phase fraction) between air and oil, does not mean the colour indicated by the colour-bar.

Phase fractions (of air, oil, water and mercury from the top) at the early stage of the simulation (Time=0.1 s).

On the other hand, the outflow of mercury accompanied by the outflow of water is the real shown in the following snapshoot (figure).

Phase fractions (of air, oil, water and mercury from the top). No inter-cellular interpolation.

4. Post-Processing

Phase fractions (of air, oil, water and mercury from the top). No inter-cellular interpolation.