Visualization of pressure distribution by applying moire topography to free-surface water table

Moire topography is applied to a free-surface water table in order to observe the pressure distribution in a gas flow. Given the water table, the time and size of a gas flow can be extended (Takasaki, 1970), while by using moire topography, the contour line map of water depth, and thus the isobaric line map for a gas flow, can be visualized (Barclay et al., 1963). The inclined grid method was developed to discriminate between the rise and fall of the water surface and to achieve high sensitivity. The switching action of an attachment jet by a control jet is used as an experimental example. Results show that the pressure visualization technique applying moire topography to a free-surface water table is adequate for observing an unsteady flow, and can give effective data for the analysis and synthesis of fluidic elements.