Another Fluid Mechanics problem

[fire]

I'm having problem understanding this one, can clarify and help answer?

A material region is defined as one where the surface velocity W is everywhere equal to the fluid velocity V. Such a region always contains the same fluid. Is it possible to define W in a less restrictive way and still have a region always containing the same material?

Thanks

 

[Astronuc]

If the material region (sounds like 'control volume') is defined as that volume of fluid bounded by the surface and the material is fixed, then it stands that the surface velocity must be the same as the fluid velocity.

See this problem. - www.colorado.edu/ASEN/asen5227/hwk8extra.pdf[/URL]

[PLAIN]http://www.colorado.edu/ASEN/asen5227/ - notes