Dear Friends, I have some questions about the efects of sink, sources and vortices. Both sink and source in fluids mechanics, are a region near a point that attracts or repels, for example, a particle. In the case of a vortice, in adition, a particle will be atract and approach towards the central point of circular form, really spiral. My question is: a) The particle has an attraction force to the sink, and repeling force to the source? b) What happens if there are two, a sink and a source, at one distance? c) What happens, if there are two equals, sink-sink or source-source and the most important: d) Is there any book or internet page about this questions? I've googled, but nothing is about this. Best reggards.