Fluid device

Abstract

A fluid device includes: a flow path through which a fluid flows; and an ultrasonic element configured to transmit an ultrasonic wave to the fluid to generate a standing wave in the fluid in the flow path along a first direction orthogonal to a flowing direction of the fluid. The ultrasonic element includes a vibrator having a fluid contact surface that comes into contact with the fluid, and a piezoelectric element that is provided at the vibrator and that is configured to flexurally vibrate the vibrator in a normal direction of the fluid contact surface. When a thickness of the vibrator in the normal direction is t, a sound velocity of a medium of the fluid is C, an average sound velocity of a longitudinal wave transmitted in the vibrator is C′, a dimension of the flow path in the first direction is L, and a mode order of the standing wave is n, the following expression is satisfied. t < C ′ C × L 2 ⁢ n

Dependencies are inferred from the claim text.