Characterisation of Vortex Flow Control Hydrodynamics for Sustainable Drainage Applications
Lead Research Organisation:
Queen's University Belfast
Department Name: Sch of Natural and Built Environment
Abstract
The Flood and Water Management Act 2010 provides the fundamental legislative underpinning for current approaches used in the UK and is a direct response to the global challenge that faces the water industry today. Our national infrastructure system must be sustainable, resilient and with risks that are managed to minimize the impact of continued development on the natural and built environment, all priority research areas of EPSRC.
Sustainable drainage systems (SuDS) are key to addressing those challenges and Schedule 3 of the Act requires the use such systems, imposing robust discharge standards in terms of both the quantity and quality of water. Flood attenuation is the prime control system employed in a SuDS system and the vortex brake represents the most efficient method by which this can be achieved. A vortex brake works on the principle that by extending the flow path and increasing energy loss, the capacity to discharge flow reduces while not presenting a physical obstacle to the passage of the water and debris. The vortex that forms in these systems operates within the vertical plane and as such the influence of gravity, while previously assumed negligible, has proven from initial tests to be significant.
The core objective of this project will investigate, both experimentally and computationally, the differences in how such vertical vortices prime and de-prime so that the inherent hydrodynamic responses can be appraised and appreciated. A full understanding of these differences is essential for an optimum design of a vortex brake to take place.
The operational sequence of the brakes, along with an understanding of the consequence and response of any change, and an assessment of the impact on the total flow must be resolved if the interrelationships between the temporal nature of a storm and the dynamic response of the vortex control system are to be understood.
By nature, the formation of the vortex is a two phase flow problem with both water and air mixing during the priming and de-priming sequence and during a significant part of the operational cycle. Trial simulations using standard open source CFD packages has proven to be problematical during these part of the cycle. The ability for standard CFD to model in particular the surface interactions is so far limited. The project will be supported by the development of a computational analysis of the hydrodynamics process using a Lattice Boltzmann Method (LBM). LBM is a computational fluid dynamics mesoscale system that instead of solving the Navier-Stokes equations, the discrete Boltzmann equation is used to simulate the flow of a Newtonian fluid by modelling streaming and collision of particles within the flow. This methodology is relatively new and has been rarely employed in Civil Engineering flow problems. The dynamic response of that system to the temporal changes in storms will allow profiling of typical response characteristics throughout the operational cycle of a vortex brake to be determined and through that, a fuller understanding of optimal design achieved.
Sustainable drainage systems (SuDS) are key to addressing those challenges and Schedule 3 of the Act requires the use such systems, imposing robust discharge standards in terms of both the quantity and quality of water. Flood attenuation is the prime control system employed in a SuDS system and the vortex brake represents the most efficient method by which this can be achieved. A vortex brake works on the principle that by extending the flow path and increasing energy loss, the capacity to discharge flow reduces while not presenting a physical obstacle to the passage of the water and debris. The vortex that forms in these systems operates within the vertical plane and as such the influence of gravity, while previously assumed negligible, has proven from initial tests to be significant.
The core objective of this project will investigate, both experimentally and computationally, the differences in how such vertical vortices prime and de-prime so that the inherent hydrodynamic responses can be appraised and appreciated. A full understanding of these differences is essential for an optimum design of a vortex brake to take place.
The operational sequence of the brakes, along with an understanding of the consequence and response of any change, and an assessment of the impact on the total flow must be resolved if the interrelationships between the temporal nature of a storm and the dynamic response of the vortex control system are to be understood.
By nature, the formation of the vortex is a two phase flow problem with both water and air mixing during the priming and de-priming sequence and during a significant part of the operational cycle. Trial simulations using standard open source CFD packages has proven to be problematical during these part of the cycle. The ability for standard CFD to model in particular the surface interactions is so far limited. The project will be supported by the development of a computational analysis of the hydrodynamics process using a Lattice Boltzmann Method (LBM). LBM is a computational fluid dynamics mesoscale system that instead of solving the Navier-Stokes equations, the discrete Boltzmann equation is used to simulate the flow of a Newtonian fluid by modelling streaming and collision of particles within the flow. This methodology is relatively new and has been rarely employed in Civil Engineering flow problems. The dynamic response of that system to the temporal changes in storms will allow profiling of typical response characteristics throughout the operational cycle of a vortex brake to be determined and through that, a fuller understanding of optimal design achieved.