So what needs to be done? First delete the wind force field and the emitter plane. Then add an icosphere which needs to be scaled to one tenth of its original size by hitting S and then 0.1 on the Numpad. Next move it to the left side of the domain, keeping it a little away from the wall. Insert a keyframe for the location and go to frame 100. Move the tiny sphere to the opposite side of the domain and insert another keyframe.
Next set the physics of the sphere to Smoke | Flow, which will automatically create a particle system. Turn the Temperature Difference all the way to 0 and check the box next to Initial Velocity.
Next head over to the particle settings. The default setup is already quite useful. Turn off the rendering of the emitter under the Render section and in the Velocity section turn up the value of the Normal under Emitter Geometry to 4. The settings for the Emission are shown in the next figure. Notice that the emission is set to Volume and Random:
Lastly a few changes to the domain. I changed the Reflection Color of the Volume Material from red to blue. I also reduced the number of divisions to 96 and added one High Resolution Division to save baking time. This means that the strenght of the moving Turbulence Force Field in the scene needs to be increased, though. I set its strength to 2. The settings of the domain can be found in the following figure:
Things should be all set now so you can start baking. When finished, move the camera in quite a bit so the movement of the sphere starts and stops off-screen. Now you can render a cool wipe of ink through water effect. Imagine what you can do with an effect as versatile as this concerning the creation of mattes for motion graphcs!
I'm always curious how you put the effect to use, so if you did something cool with it, please also post it in the comments. If you like the effect, head over to Nion's homepage and add a comment over there!