There are a variety of problems in fluid mechanics that involve the flow out off, for example, a beaker. A typical example is that of a siphon shown below:
The typical way to approach such a problem is to use Bernoulli's equation at the top of one of the beakers and e.g. within the tube. I am yet to find a satisfactory justification for its use in such a situation. I guess we are not assuming the flow is irrotational. In which case a streamline must connect the points of consideration which seems unlikely. So what is the resolution to this i.e. why can we use Bernoulli's equation in problems such as this one?