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Alex Hanson discusses the benefits of using PDD’s Computational Fluid Dynamics (CFD) packages as a powerful tool for creativity and exploration throughout the design process.

Computation fluid dynamics (CFD) is an engineering tool used to simulate the action of thermo-fluids in a system. It is used by many industries in their development work to analyse, optimise and verify the performance of designs before costly prototypes and physical tests. PDD apply it somewhat differently.

When can CFD provide an advantage?

CFD is best used in cases where the system behaviour cannot be calculated using conventional calculation – not necessarily because of the complexity of the maths theory – but because of the complexity of the overall system or its geometry. As Graham Lacy, PDD’s Technical Director observes, ‘We so often find that the engineering challenges is not the simple application of complex theory – but the complex application of simple theory’.

How has PDD used CFD effectively?

The story started long-ago when PDD was one of the early adopters of 3D CAD (Computer-Aided Design) in the early 90s with SDRC. This was primarily for design, communication and manufacturing reasons – and yet paradoxically this package had emerged itself from Finite Element Analysis (FEA) modelling. Our adoption of FEA soon after CAD supported our work in structural, rugged and sealed products and allowed us to be pioneers in their performance.

Alongside CAD, PDD has extensive experience in fluid technology projects; developing a broad range of products for various industries around the world including pharma drug delivery, HVAC, domestic appliances and technical packaging.

CFD has proven itself to be a powerful and effective tool in these projects. Having first used an ANSYS product, PDD also recently acquired Solidworks Flow Simulation. This integrates directly with 3D CAD modelling and its access and quick learning curve is particularly suited to fast and concurrent work in early stages. PDD has already applied it to several recent innovations, including:

• Miniature, non-contact fluid mixing for viscous formulations
• A fast-acting disc valve oscillating at 20Hz
• Improved centrifugal pump efficiency
• Cold and hot fluid blending with minimum back-pressure
• Noise reduction within a bedside medical product
• Flowrate inference from a single pressure sensor

PDD operates a highly integrated and concurrent work process within its cross-discipline structure. Our simulations are conducted by the engineering designers, not separate analysts, meaning the input and results can be used as part of a rapid and iterative design process, exploring many alternative concepts as well as design parameters.

How does CFD benefit your workflow?

As a design engineer at PDD, I have found CFD to be very useful that has allowed me to visualise the invisible. By interrogating the flow at different cross sections I can learn much more than I ever could with physical models. The link between the 3D CAD and CFD software means I can quickly iterate and optimise a design based on the CFD results to achieve performance levels that wouldn’t have been possible previously.

Carrying out CFD to predict the function of key design elements at an early stage reduces risks that would otherwise persist until later stages where change is more costly. By introducing CFD simulation earlier into the design process, PDD has been able to be more adventurous in its concepts and their selection and confident in the outcome of design intent. Uncertainties are qualified sooner and risks are designed-out when it is easier and quicker to make changes. Virtual prototyping with CFD simulation, often alongside FEA simulation, means that physical prototypes exist to confirm predictions and not test to establish them.

Our cross-discipline and cyclical approach to innovation is a natural and welcoming process for CFD, as FEA before it, and any methodology that improves innovation and practices.

The outcome of PDD’s recent investment into CFD has already been effective for our clients, allowing them to patent innovative new devices and technology and protect their core differentiation. It has already helped products to be more efficient, improve the efficacy of medical therapies and reduce product noise and vibration.

If you have any questions about PDD’s CFD or FEA simulation capability and its relevance to medical devices, consumer durables and packaging or rugged industrial equipment please get in touch at [email protected].