This statement isn’t actually true, most solids don’t flow, at least at Earth’s surface temperatures and pressures, but given the right conditions, maybe it is true. Regardless, here is a photo of a flow tank at the Mount Washington Weather Discovery Center in North Conway, New Hampshire. The water contains particles so you can see the flow from left to right more easily. The mounds at the bottom are solid and represent Mt. Washington’s shape, so you can see the ‘winds’ flow smoothly up one side of the mountain (left) and then become turbulent (more variable) in the lee side (right side in this image). The snapshot does not do this tank justice, it’s mesmerizing. Also, there is a magnetic bar you can move around inside the tank to disturb the flow (see image below). I’d rather have this than a fish tank.