The use of CFD coupled with physical testing to develop a new range of vortex flow controls with attributes approaching the ideal flow control device

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Vortex flow controls (VFC) are devices which are well suited for use in drainage systems, as they exhibit non-constant, non-linear discharge coefficients that can be tailored to approach that of a constant flow-rate device. Also, they have no mechanical components or power requirements and have a reduced risk of blockage compared with traditional flow controls. However, due to their complex bi-stable discharge behaviour and the influences of turbulence, the design and scaling of these devices, is not a trivial process. In this paper a VFC design methodology is presented that enables the VFC geometry to be determined and optimized to approach the ideal hydraulic behaviour, for a given discharge limit. This is achieved through the calibration of simplified, axi-symmetric vortex solutions of the Navier-Stokes relationships, by means of Computational Fluid Dynamic (CFD) analysis and experimental hydraulic assessment. © 2011 ASCE

Modelling of vortex flow controls at high drainage flow rates

A number of vortex flow control (VFC) devices for urban drainage systems are investigated computationally at high flow rates, for which a confined vortex dominates the flow regime. A range of turbulence models, including both eddy viscosity and Reynolds stress closures, are compared with in-house experimental measurements of head loss and internal pressure measurements. Single-phase and multi-phase (free surface) calculations are also compared. Very good agreement with the experimental data was obtained when the swirl parameter of the device was below 3.14 for predictions made using the Reynolds stress closure formulations. For devices with swirl parameters above this value, the computational methodology was found to under-predict the head loss of the device. This was attributed to poor calibration of the turbulence model for swirling flow scenarios in which the pressure gradient and diffusive (turbulent) forces in the flow are comparable