FLUENT 6 - Creating an animation in a 3d VOF case


There might be an instance of an application where iso-surface of half the maximum value of volume fraction of secondary phase needs to be displayed. A typical application where this need arises is a water bubble striking a baffle , the geometry of which is as shown at <a target=_blank href="http://www.fluentusers.com/support/solutions/1008/geometry.gif">http://www.fluentusers.com/support/solutions/1008/geometry.gif</a>http://www.fluentusers.com/support/solutions/1008/geometry.gif

In this example, an animation of a bubble striking the baffle is to be created. If the maximum value of VOF of water during the simulation falls below 0.2 and displaying an iso-surface with this value results in disappearing of the bubble in the animation. An iso-surface created with half the maximum value of vof of water represents the shape of bubble.
Here is the procedure to create an iso-surface of half the maximum value of vof of water(secondary phase):

The maximum value of vof needs to accessed from Fluent through a function. Based on the value, a scheme function is written to create an iso-surface.

File "drop.scm"

********************drop.scm***********************
(define phase-value (cdr (list-ref (%fill-node-values 'water-vof) 0)))
(ti-menu-load-string (format #f "surface iso-surface water vof droplet , ~d ," (/ phase-value 2) ))

*****************************************************************************

is the scheme file which uses the function to access value of VOF and commands to create an iso-surface called "droplet". The scheme file is read into Fluent using Solve--->Execute Command. Thereafter the so created isosurface is displayed and a tiff file is created. To summarize, here is the algorithm followed:


1) Access maximum value of VOF of water from Fluent through a function.
2) Create an iso-surface with half the maximum value.
3) Display and take a hard copy of the iso-surface.
4) Delete the iso-surface.

Following are the commands which need to be used in Fluent through Solve--->Execute Commands

*****************************************************
(load 'drop.scm)

dis/sur-grid 6 4 droplet 1 2 5 , /display/view/restore-view ,

/dis/hc drop_%t.tiff

/surface/delete-surface droplet

*******************************************************************************************

Animation at <a target=_blank href="http://www.fluentusers.com/support/solutions/1008/animated-mesh.gif">http://www.fluentusers.com/support/solutions/1008/animated-mesh.gif</a>http://www.fluentusers.com/support/solutions/1008/animated-mesh.gif

shows the above strategy in tracing the bubble.





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