Non-Invasive Measurement of Fluid Force on Multi-Particles in Oscillatory Flow

We have developed a wireless Lagrangian sensor system for measurement of the fluid force exerted on a free-moving particle in liquid. The sensor particle mainly consists of an acceleration sensor, a magnetometer and a wireless module. The sensor particle detects instantaneous acceleration (i.e., force divided mass) and transmits the signals to a receiver wirelessly. We have applied our system to the measurement of the fluid force acting on a particle in oscillatory flow. Firstly we have measured the force acting on an isolated particle for the verification of the system. The measured results agree well with the analytical results derived from fluid force models. Moreover, we have applied our system to oscillatory flow with particle assemblage. The results suggest that the unsteady fluid force on multi-particle system is quite different from that on isolated system.