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This web page is about CellFlow, a freeware open source CFD program that I developed.
More accurately, it is a heat, flow and sound simulator.

Von Karman Animation

The main features of CellFlow are:
-Freeware open source.
-It can do any number of dimensions: 1, 2 and 3 dimensions, but also (just for fun) 4 and higher.
-It does an animation as it calculates.
-It works as a dynamical direct numerical simulation: With compressible flow, in explicit time dependence.
-Input files generated by a spreadsheet.
-Models pressures, flows, temperatures, and chemical species.
-Also suitable for acoustic simulation, and for simulation of aero acoustics (eg whistles)

To be fair, I can think of a few drawbacks:
-Only (topologically) rectangular grids. But cells need not be equal in size.
-No implicit turbulence model is implemented. But if you use a fine enough grid, you get turbulence explicitly.

Both of these drawbacks can of course be addressed. Maybe I will work on it if I have time.

Here are some pictures I generated for a ball in a channel, in 2D, 3D, and 4D.
Velocity plot of von Karman
2D, 3D and 4D velocity plots for an n-dimensional ball in a channel.
For 2D, this gives the well known "von Karman vortex street".
The 3D and 4D pictures are of course cross sections.

In dimensions greater than 2, you need to select the "slice" you wish to view in your 2D screen. Below is a screen shot showing how that goes:
How to slice

Here is a screen shot of a spreadsheet generating an an input file:
CellFlow input

Animation of free convection:
Free Convection Animation
In this animation, temperature is plotted.
The vertical strip is a body at constant high temperature, and the horizontal strip is kept at constant low temperature.
So hot air is created around the hot strip, and due to buoyancy, the air rises to to cold strip, where it looses heat.
The animation shows how a simple geometry can give rize to complex behaviour.

Whistle animation:
Animation of whistle

Some Downloads:
Windows Executable file
Rudimentary manual
Von Karman 2D example
2D free convection example
Whistle example

My web page:
 Questions, mail me at Westy31@xs4all.nl

Source code:

The probgam was made in Visual basic 6.0
Most of the source code is in the CellFlow.bas file (Readable in ASCII)
The '.frm' files you need if you have VB 6.0, to make the windows/diaglogs.
the 'vbp'file is for the VB 6,0 IDE
The .ico file is the icon