Computational Fluid Dynamics (CFD)
Optimising your treatment process & predicting mixing quality

Boost treatment efficiency, reduce chemical and energy use, and ensure control in mixing processes
Mixing plays a critical role in every stage of treatment – from aeration and sludge management to MBBR oxidation and sedimentation. Too much or too little mixing can compromise performance, driving up chemical and energy consumption. That’s why accurately predicting mixing quality is essential for optimized plant operation. One of the most effective tools for achieving this is Computational Fluid Dynamics (CFD).
At Xylem, we pioneered the use of CFD in water and wastewater treatment over four decades ago. Our specialized engineering team supports the entire modelling process – from setting model boundaries and creating computational meshes to interpreting results and delivering validation. This expertise helps you uncover accurate, cost-effective solutions to any challenges in your mixing processes.
Test, Simulate, Solve: The Power of CFD and Lab Validation at Xylem
Answering your common questions on CFD
Computational Fluid Dynamics (CFD) is a specialised field within fluid mechanics that uses numerical analysis to solve and predict the behaviour of fluid flows. It enables the simulation of turbulent fluid flow, heat and mass transfer, multiphase flows, chemical reactions, fluid structure interaction and acoustics to gather detailed insights into how the fluid behaves. This allows advanced modelling during the design and post design stages of a treatment process to identify issues that may arise after commissioning of the plant or once live to support with troubleshooting.
CFD provides detailed 3D modelling of a treatment design which includes details such as construction structures, diffusers, mixers, pipes, and other installations that will have an effect on the mixing. The process enables a plant to test various designs, flow conditions, air loads and operation scenarios and refine designs digitally before creating physical prototypes and progressing to the build. This can reduce the time and cost associated with traditional trial and error approaches. Ultimately, this predictive capability leads to reduced risk and optimisation of treatment equipment and process performance, cost, and environmental impact.
Yes, using CFD can significantly improve a plant's sustainability by helping optimise energy use, reduce emissions, and enhance overall efficiency. Through scenario modelling, CFD analysis helps identify areas of the mixing process where energy losses occur and areas where energy efficiency performance can be enhanced. Operators can be confident they are making data driven process decisions which support their plant’s sustainability goals.
When designing a treatment plant, it is vital to consider total cost of ownership to ensure it meets budget requirements and is cost effective throughout its operating life. CFD can help reduce investment costs through optimising the design to ensure construction is as efficient as possible and installation and commissioning runs smoothly. Analysis of operating conditions through CFD also enables experts to advise on the best strategies to minimise operational costs. For example, through looking at horizontal flow effects, we can combine aeration with mixing to increase air bubble retention time to enhance oxygen transfer, which ultimately leads to energy and cost savings. CFD can also help with unplanned costs and downtime. CFD reduces downtime and costs by preventing mixer failures through scenario planning.
Optimising the mixing process is one of the key benefits of CFD analysis. CFD can help reduce maintenance efforts by identifying issues like sediment or floating debris early—saving time and costs. Importantly, CFD helps existing plans troubleshoot and take action to reduce costs, but it is also instrumental at the design stage, when this optimisation can take place and solve problems before they occur.
Our range of Mixers
Flygt mixers ensure optimized process results with significant energy savings. Our assortment of mixers includes a wide range of different models and sizes to match any demand in wastewater and industrial processes.
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Single Speed Mixers
Reliable efficient mixers for any tank shape and size
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Adaptive Mixers
High-efficiency adjustable-speed mixers to match process needs
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Mixing Accessories
Accessories compatible with Xylem's Flygt mixers