part contains further developments of the study of the Kelvin Helmholtz
instability to illustrate possibilities of Fluent:
time wave study. This time the height is 0.3m the additional space being occupied by the hid phase.
Click here for a picture of this mesh.
As with the mesh, the used model is the same as in the time wave study. The third phase is liquid gasoil which is slightly lighter than fuel. The fluids are layered with heavier on the bottom an lighter on top. As we use 3 phases the vortexes are moving in most settings.A-2 Model
The interface 1 between water and fuel is perturbed whereas the interface 2 between fuel and gasoil is undisturbed
The results showed that the oscillation at the interface 1 affected the interface 2. I seems like the interaction between both interfaces has a stabilizing effect.A-3 Result
For example with water 2
m/s, fuel 0 m/s, gasoil 2 m/s. .
at time 0.34s
a water 2 m/s, fuel 0 m/s, gasoil -2 m/s setting, the oscillation are moving
in opposite direction but there the same evolution occurs.
The upper and lower faces are walls. The other faces are periodic ones.
Click here to see a picture of this mesh
The model used and operating conditions are the same as for the time wave study. The initialization UDF init3d.c is an evolution of init.c. This time the is a perturbation on the x-axis and the z-axis. The wavelength in both direction is 0.1m. The fluid is flowing along the x-axis.B-2 Model
The image below show the result of the computation after 0.1s. The surface is the 0.5 iso-value of fraction of fuel (i.e. the interface). The color is the velocity magnitude.B-3 Result
to see an animation of the instabilities formation with a 0.01 time step.
This image shows the particular shape of the instability.