Whether the hourglass is vibrating, possibly causing different flow conditions. This study gives a horizontal sine wave to the hourglass. The experiment is conducted with different variables, such as frequencies and amplitudes generated by two motors. To compare the differences between the different variables, we look at the surface layer, the whole flow field, and a specific particle inside the hourglass.

Quicksand During Earthquakes – the Effect of Horizontal Vibration on the Hopper