What we compute
Industrial aerodynamics
Methods are worth having only if they answer questions somebody actually has. We apply high-order simulation to real engineering geometries — racing cars, aircraft wings, fans — usually in cases where the standard industrial approach gives an answer that is not accurate enough to design with.
Industrial CFD is dominated by methods that model turbulence rather than resolve it. They are fast, robust and well understood, and for attached flow over simple shapes they are entirely adequate. They become unreliable exactly where the interesting engineering is: separated flow, wakes interacting with downstream components, vortices that have to be tracked a long way without being smeared out by the numerics.
Scale-resolving simulation avoids the modelling assumption by computing the turbulence directly, but has historically been too expensive and too fragile on complex geometry to use in a design cycle. Much of our applied work is about closing that gap, and it takes real cases as the test: a Formula One front wing, whose wake determines the performance of everything behind it and which we have validated against wind-tunnel experiment; a full high-performance road car; an inverted multi-element wing in ground effect; an aircraft wingtip vortex, which sets the spacing between aircraft on approach and so the capacity of an airport.
A second strand is turbomachinery, through a knowledge transfer partnership with a fan manufacturer. Here the questions are different: not what happens in one carefully chosen configuration, but how to search a design space efficiently, and how to trade aerodynamic performance against the noise a fan emits. That work combines simulation with surrogate models and optimisation, because the simulations are too expensive to put directly inside an optimiser.
Working this way keeps the methods honest. Complex geometry is what breaks mesh generators, industrial timescales are what expose a solver that is only fast in principle, and a partner with a product to ship asks questions that a purely academic test case does not.
Published version, CC BY, fig. 7
Funded by
Who works on this
All of the team
Prof. David Moxey
Group leader and project leader of the Nektar++ framework.
Previously
Dr. Hamid Motamedi-Zokae
Worked with Torin-Sifan Ltd to investigate CFD-driven HVAC design.
Now: CFD Engineer, D-Tech Rotary Steerable
Dr. Mohammad Moshfeghi
Impellor design and CFD modelling in a knowledge transfer partnership with Torin-Sifan Ltd.
Now: EDU Cooling and Lubrication Lead Engineer, Jaguar Land Rover
Recent papers
All publications-
Comput. Phys. Commun., vol. 331, pp. 110473
Scale-resolving simulations of high-Reynolds-number incompressible flow are often limited by the Courant–Friedrichs–Lewy (CFL) restriction of explicit time-stepping schemes, leading to small steps and long times-to-solution. We systematically compare two implicit formulations of the velocity correction scheme – a linear-implicit approach and a sub-stepping (semi-Lagrangian) method – with a standard semi-implicit formulation in a high-order spectral/hp element framework. The schemes are assessed in terms of stability limits, temporal accuracy, and computational performance for implicit large-eddy simulation of the Imperial Front Wing benchmark, a complex high Reynolds number geometry with curved surfaces that imposes strict CFL constraints. The sub-stepping scheme extends the stable time step size by a factor of 20, and the linear-implicit scheme by up to a factor of 100 when equal-order velocity and pressure spaces are used. While increasing the cost per time step, the linear-implicit scheme reduces the time-to-solution by up to a factor of 8.7 at this largest step, whereas the sub-stepping scheme reduces it by only 12%. With application targets of 1% for mean lift and 5% for mean drag, the fastest accepted linear-implicit case reduces time-to-solution by a factor of 1.53 at ten times the CFL-limited step. The main-plane separation bubble is already substantially shortened at this step, showing that force agreement can mask changes in transition-sensitive flow structure. The results quantify the trade-off between stability, accuracy, and computational cost for implicit velocity correction schemes on complex geometries and provide guidance for selecting time integration strategies in large-scale scale-resolving simulations.@article{wustenberg-2027, title = {Implicit velocity correction schemes for scale-resolving simulations of incompressible flow: Stability, accuracy, and performance}, journal = {Comput. Phys. Commun.}, volume = {331}, pages = {110473}, year = {2027}, doi = {10.1016/j.cpc.2026.110473}, url = {https://www.sciencedirect.com/science/article/pii/S0010465526004546}, author = {Wüstenberg, H. and Liosi, A. and Sherwin, S. J. and Peiró, J. and Moxey, D.} } -
High-Fidelity Sliding Mesh Method for Moving Geometries in Turbomachinery Applications
Int. J. Turbomach. Propuls. Power, vol. 11
The accurate, high-fidelity modeling of moving geometries involving translation and rotation is important in fluid mechanics applications, particularly turbomachinery. These simulations facilitate the analysis of various turbomachinery stages, where complex movements are integral to their functionality. We integrated a sliding mesh capability into the iLES/DNS compressible Navier–Stokes solver within Nektar++, which is a spectral/hp element open-source framework. Static and moving regions of the finite element mesh are coupled across a non-conformal interface using a point-to-point interpolation method (PTPM). The solver is verified on two canonical benchmarks, the isentropic vortex and Couette flow, and validated on the T106A low-pressure turbine cascade with an upstream translating bar that generates inflow wakes, emulating rotor–stator interaction. This paper aims to provide robust validation of the new solver developments and supply a tool to understand how the upstream bar motion influences the downstream blade efficiency, which is crucial for enhancing turbomachinery design and performance.@article{ye-2026, author = {Ye, Junjie and Vivarelli, Guglielmo and Isler, João and Moxey, David and Sherwin, Spencer and Cantwell, Chris}, title = {High-Fidelity Sliding Mesh Method for Moving Geometries in Turbomachinery Applications}, journal = {Int. J. Turbomach. Propuls. Power}, volume = {11}, year = {2026}, number = {4}, url = {https://www.mdpi.com/2504-186X/11/4/40}, doi = {10.3390/ijtpp11040040} } -
Eng. Appl. Comput. Fluid Mech., vol. 19, pp. 2585337
Centrifugal fans find widespread application in building ventilation and air-conditioning systems. Nonetheless, they face challenges in meeting the growing need for energy efficiency, better performance, and reduced noise levels. In this paper, we examine simultaneous aerodynamics and aeroacoustics optimization of a backward-curved centrifugal fan. The study begins with the validation of 3D computational fluid dynamics (CFD) models for both aerodynamic and aeroacoustic simulations against experimental data. Using these validated models, two separate simulation domains are employed for aerodynamic and aeroacoustics analyses, and a selection of CFD simulations performed using a Latin HyperCube sampling. Based on this data, surrogate models were trained independently to predict aerodynamic and aeroacoustics behaviour based on five geometric design parameters, including the blade flow angle distribution from leading edge (LE) to trailing edge (TE). We then perform three optimization scenarios—purely aerodynamics, purely acoustics, and combined aerodynamics-aeroacoustics using the surrogate-based NSGA-II optimization algorithm and compare the optimal results against the baseline geometry. We show that aerodynamics optimization demonstrates up to an 8% increase in efficiency within the operating range, while the acoustics optimization achieved a reduction of up to 4 dB in the maximum sound pressure level, at the expense of significantly reduced flowrates. The aeroacoustics optimization yielded a balanced outcome, maintaining baseline flowrates while delivering a 3.9% increase in efficiency and a 3.5 dB reduction in maximum sound pressure level. These results underscore the trade-offs between aerodynamics performance and acoustics behaviour and highlight the potential of optimization strategies tailored to specific operational goals.@article{zoka-2025, title = {Surrogate-based evolutionary optimization of aerodynamic performance and emitted sound for an impeller fan}, author = {Zoka, H. M. and Moxey, D. and Tabor, G.}, journal = {Eng. Appl. Comput. Fluid Mech.}, year = {2025}, volume = {19}, number = {1}, pages = {2585337}, doi = {10.1080/19942060.2025.2585337}, url = {https://www.tandfonline.com/doi/full/10.1080/19942060.2025.2585337} } -
Multi-Point Aerodynamic Optimization of a Backward-Curved Impeller Fan
Turbo Expo: Power for Land, Sea, and Air, vol. 87981, pp. V006T10A008
Centrifugal fans find widespread application in building ventilation and air-conditioning systems. Nonetheless, they face challenges in meeting the growing need for energy efficiency, better performance, and reduced noise levels. These limitations stem from the inherent constraints imposed by the circular arc blade design. In this paper, aerodynamic optimization of a backward-curved centrifugal fan was carried out. For this purpose, 3D computational fluid dynamics (CFD) simulations of the initial fan were first validated against test data. Then, using five geometric design parameters, the blade flow angle distribution, from leading edge (LE) to trailing edge (TE), was optimized within its operating range by means of a surrogate-based optimization technique. Efficiencies at different operating points of the fan were selected as objectives while the constraints of the optimization practice include flowrates as well as blade thicknesses of the initial geometry. The suggested optimum geometry generated from this process was independently simulated by CFD to assess the meta-model predictions. The computed results demonstrated up to a 1.7% increase in efficiency in its operating range compared to the initial model. Moreover, studying the features of the flow passing through the blades indicated an improved aerodynamic behavior with reduced separation zones for the optimized geometry compared with the initial one. Geometric comparison of initial and optimized geometries also revealed a curvature redistribution in the fan blades.@inproceedings{motamedi-2024, title = {Multi-Point Aerodynamic Optimization of a Backward-Curved Impeller Fan}, author = {Motamedi Zokae, Hamid and Tabor, Gavin and Moxey, David and Page, Martin and Stokes, Martin}, booktitle = {Turbo Expo: Power for Land, Sea, and Air}, volume = {87981}, pages = {V006T10A008}, year = {2024}, doi = {10.1115/GT2024-127168}, organization = {American Society of Mechanical Engineers} } -
Large eddy simulation of an inverted multi-element wing in ground effect
Flow Turbul. Combust., pp. 917-944
Due to the proprietary nature of modern motorsport and Formula 1, current scientific literature lacks relevant studies and benchmarks that can be used to test and validate new methods. Due to the release of a free geometry - the Imperial Front Wing - we present a computational study of a multi-element aerofoil at a ride height of 0.36h/c and a Reynolds Number of 2.2 × 105. A 0.16c slice of the Imperial has been examined using high-order Spectral/hp Element Methods. Time averaged force data is presented finding lift and drag coefficients of -8.33 and 0.17 respectively. Transient analysis of the force- and surface pressure data resulted in salient mode identification with respect to the transition mechanisms of each element.The mainplane and flap laminar separation were studied and the cross-spectral phase presented for the lower frequency modes. At a St=40 an in-phase relationship was identified between mainplane and flap Laminar Separation Bubbles, whilst at St=60 a distinct out-of-phase relationship was identified. Wake results including wake-momentum deficit and turbulent kinetic energy plots have been presented - showing wake meandering and subsequent break down due to a Kelvin-Helmholtz instability. These results, particularly the transition mechanisms will allow for the construction of a data set to validate novel methods in this area.@article{slaughter-2023, title = {Large eddy simulation of an inverted multi-element wing in ground effect}, author = {Slaughter, J. and Moxey, D. and Sherwin, S. J.}, journal = {Flow Turbul. Combust.}, year = {2023}, number = {110}, pages = {917-944}, doi = {10.1007/s10494-023-00404-7}, url = {https://link.springer.com/content/pdf/10.1007/s10494-023-00404-7.pdf} }
Collaborators
- Spencer Sherwin Imperial College London
- Gianmarco Mengaldo National University of Singapore
- Gavin Tabor University of Exeter
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