Editing The leaky tank mystery (section)

==Project description==
Imagine one of those railcars that has a big horizontal water tank. Pretend it is frictionless. Imagine the tank is full. Imaging there's a hole at the top to let air in. Imagine the tank is leaking through a small hole on the left bottom side of the tank. Assume the jet of water is vertically downward. Does the resulting change in momentum push the railcar to the left or the right?

This is a very famous problem that has never been properly solved. We need finally put it to rest. We will give you papers showing attempted solutions that contradict each other. You may try to search for more papers on the topic.

The experiment is almost impossible to do in practice as the forces are smaller than the friction you get in real life. This explains why there are contradictory solutions. This illustrates an important principle in engineering that your can never be sure of the theory until you do the experiment.

But the modern world of engineering now has simulation tools that we trust and are as good as an experiment provided we don't feed it with wild parameters outside of the range that models are valid.

We want you to do the "experiment" in simulation using Comsol and/or Ansys. The Faculty has licences. Find the answer. Then go and find which theory paper got it correct. Then nicely explain that theory yourself, written out clearly in your own way.

This is a beautiful classic problem and it will be a lot of fun. If you can think of a clever way to actually do a low friction experiment and video it, this will be a cherry on that cake and your name will go down in history. Suggest you design a rectangular tank and suspend it hanging with four cords attached to the corners. You'll need to design a release valve for the water that is actuated by a remote (because you can't touch the tank). Suggest you bounce a laser pointer off the tank as a way of measuring deflection. However, you need to fully simulate the tank first to get all the size parameters right to optimize the size of the deflection.