Physics

» Paul A. Heckert - taphonomy and turulent flow dynamics

Because this is a student project, it is best to keep things simple. Students at this level will not have the mathematical skills or knowledge to derive the type of equation you are looking for. It seems more at the level of a doctoral student in physics or engineering. If you just give the students an equation to use, they will plug in numbers and learn nothing.
A better approach would be to let students find an emperical equation that works. (That is where the Manning equation originally came from.) Let them do experiments and make appropriate graphs for the variables you have in mind. Then ask are they linear or a power law? Is there a coefficient that depends on the bone size or shape? etc. With the right guidance, precalculus students can do this. The results may not be completely rigorous, but they will learn a lot about how to do experimental science. That is of course the point of a student project.
Good Luck.
Paul Heckert