A cavitating venturi is a passive device that uses hydrodynamic cavitating flow to anchor the mass flow rate. The inter-phase interactions impart inherent cavity oscillations in the venturi operation, presenting challenges in understanding its flow behaviour and developing reliable numerical models. Cavitating venturis are passive devices with no moving parts. This unique feature makes the device an excellent flow rate controller in various industrial applications. Systematic experiments conducted as a part of the project experimentally characterised the nature and dynamics of the cavitation zone in planar cavitating venturi. Predictability limits of the existing two-dimensional models have been assessed using scaling studies in axisymmetric and planar venturis. A simple one-dimensional model has been constituted to aid in the design and sizing of cavitating venturis. An App has been developed based on this model to aid the venturi sizing. The beta version on this App is being evaluated by LPSC, ISRO with the data available from their cavitating venturis in the fuel feed control lines of rocket engines.