It would be great to be able to have the "water" react to the particles. Hopefully fluid dynamics will be added in a future ver. of Carrara. I have had some luck using an AVI file to drive displacement of a mesh in a water animation. Any chance that something similar might work for your animation? I'm almost finished building my loco, so I plan to download and purchase Cognito tonight . I'll let you know how that goes and I'll certainly post a link to the animation. Thanks again.