Services: Simulation

The availability of vast computing power is accelerating technical development at an unprecedented rate. By harnessing this capability and deploying advanced simulation techniques, your organisation can become a market leader in your field.

For decades, Xi has been working at the forefront of the world of simulation. Globally recognised for our expertise in this arena, we work with leading technology companies in a wide variety of markets. Using digital engineering tools, Xi continually pushes the boundaries of what is possible through Multiphysics to solve all kinds of complex engineering challenges.

By validating our sophisticated models with real world data, we can provide a risk-free environment in which you can improve and optimise your product.

Our simulations accurately represent how your system will function in the real world, providing a robust test bed for a wide range of scenarios. This approach accelerates your design process, reduces your time to market and minimises technical risk.

Working with Xi gives you immediate access to our expert simulation capabilities. We work as part of your R&D department, negating the need to upskill your own team. However, depending on your growth plans, we can also provide the training to develop this expertise in-house.

We work at every scale: at material level; from MEMS scale up to immense energy generating devices and systems. Our team adapts to your needs, working alongside your technical team to fully understand your design and make informed recommendations for next steps on your project. We take great pride in delivering the very best custom solutions and software to our clients.

Talk to us about your project.

Simulation Specialisms

Numerical simulations using methods such as finite element analysis, boundary element methods and ray tracing are highly effective in aiding product and system design.  Applying these methods drastically reduces the time to market and expenditure related to the manufacture and testing of prototypes.

Whether an organisation is a start-up or an established company with a dedicated R&D department, they often lack the capacity, software or experience to perform these numerical simulations. This is where Xi can help: by working with our clients’ engineering teams to develop bespoke numerical models; and by collaborating with the engineers to determine a comprehensive modelling approach based on inputs such as geometry, material, physical processes and loads, along with the required model outputs such as stress field, acoustic load, frequency response and localised flow rates.

Xi’s philosophy is that models are never perfect and require a validation step to make the results meaningful, and we work closely with our clients to determine an appropriate validation process for each project.

Design changes during development often mean that minor modifications to a model are required. This may be, for example, changing the thickness of one component for commercial reasons. It is important that the impacts of any such changes on the frequency response, fatigue life or fluid flow of a system are determined. Such changes are not easy to make by non-experts due to the complexity of the underlying model, resulting from the interconnected geometric parameters, meshing and boundary conditions. Xi solves this issue by creating user-friendly front-ends to our models using COMSOL Applications which provide the end-user with a suite of parameters that can be changed without damaging the underlying model.  These front-end applications make it possible for non-experts to make changes, run the model and obtain results without further input from Xi or a client’s simulation department. These COMSOL Applications have proven to be valuable to technicians who require rapid modelling output or organisations who lack their own simulation departments.

Electromagnetic simulation helps you to improve efficiency, ensure compatibility and guarantee performance in complex and noisy EM environments.

Electromagnetic modelling benefits system design in a rapidly growing range of applications from MEMS sensors and actuators to vehicle motors, wireless communication devices, and generators in wind turbines.

In all these areas, Xi has helped clients understand their systems better and enabled acceleration in design for demonstrating novel concepts or improving device performance, efficiency, robustness, and safety.

Bespoke device design in geometries and materials can be very complex. In many cases, finite element analysis is the only way to properly visualize this. Working with Xi, you can can validate simulations against your baseline legacy or prototype systems, and then further improve your design without the expense of physically building and testing multiple configurations. Not only do we help our clients develop accurate models, we also ensure they fully understand what you are observing in order to make improvement to their systems.

We model a variety of electrostatic, AC, or time-varying electromagnetic systems in COMSOL Multiphysics that can be built in 2D, axisymmetric, or fully 3D bespoke geometries, ranging from microfabricated sensors up to large industrial power systems.  Xi can help optimise designs by investigating effects such as electromagnetic fields, EMI/EMC, wave propagation and resonance effects in high-frequency applications.

We use the COMSOL Multiphysics AC/DC and RF Modules, which have an array of built-in materials, including typical conductors and insulators, piezoelectric materials, and nonlinear ferromagnetic materials. Built-in model structures such as the coil feature make designing inductors and motor components straightforward and computationally tractable. Heating and mechanical force analysis can be performed by coupling the electromagnetic calculations. As with all COMSOL physics modules, AC/DC may be coupled to the Optimization Module to explore the influence of multiple properties which may be simultaneously varied.

Because so many electromagnetic applications also involve the generation of heat or mechanical forces, the fundamental Multiphysics approach behind COMSOL makes it ideal for understanding such systems as a whole. This flexibility, along with high quality visualization and data analysis capabilities makes it easier to translate simulation results into practical action items, accelerating your innovation.

The modelling of dynamics is used to ensure that a product is not under-engineered and therefore at risk of failure. It’s also important to determine that a product is not over-engineered, resulting in unnecessarily high costs in materials and fabrication time.

Xi’s modelling approach to dynamics reduces the need to produce and test physical prototypes, providing our clients with a quicker, cheaper route to market with a superior product.

Our experience in modelling dynamics is extensive. We provide vibrational analysis expertise across a vast range of markets and products: determining the amplitude of vibration in various systems and structures: testing loudspeaker systems; calculating stresses and survivability in the built environment during earthquakes; determining the fatigue life of robotic systems and tidal turbines working in incredibly hostile environments; optimising designs in the transportation sector to improve passenger comfort.

We can examine structures with respect to stresses under static and dynamic loads, and optimise structures to improve vibrational behaviour, fatigue life or acoustic characteristics.
We model ground and structure-borne vibration and its effects on inhabitants and buildings and apply modelling techniques to assess the risk of failure in structures. We often work on building and bridge dynamics in collaboration with Gerb.

We are capable of modelling at every scale: from the response of a thin membrane to an acoustic load at micrometer scale; to the response to wind loading of a 200m wind turbine.

The variety of forces we model include rotational dynamics, seismic, electromagnetic, electrostatic, acoustic, fluid flow and piezoelectric effects. These sophisticated models can be used to examine the harmonic response of structures or their time-dependent behaviour.

Xi can also provide structural dynamic analysis of constructions to help our clients comply with strict occupational health and safety regulations.

The demand for efficient structures, systems and lightweight materials brings with it dynamics challenges which can become a limiting design factor. Our accurate, validated analysis can help you meet those challenges, optimise your product and ensure that it lasts the test of time.

To understand, analyse and mitigate for all types of noise and acoustic issues, Xi uses a variety of modelling methods. Our approach depends on the specifics of the project, principally the size of the acoustic domain relative to the minimum wavelength which is being modelled. Another important consideration is understanding the nature of the output required and its subsequent use.

When the size of the acoustic domain is comparable to the wavelength of the sound being modelled then finite element (FE) analysis is favoured. An example of this modelling is the low-frequency response of a headphone speaker where the wavelength and acoustic domain are both centimetre scale.

In situations where the acoustic domain becomes large with respect to the wavelength, it is necessary to use other approaches to model the sound field. Boundary element method (BEM) provides a means to model large structures without requiring large numerical meshes, which are a requisite for FE. An example of the use of BEM is the modelling of the acoustic output of wind turbines with 200m tip heights and their effect on local communities.

Ray tracing and parametric equation approaches are also an efficient way to model the propagation of noise for point and linear sources, such as motorways and construction activity. Xi uses these approaches for modelling building acoustics, such as concert hall acoustics, and for modelling underwater noise and its impact on marine species.

A diffusion equation approach is a very effective way of modelling acoustics of coupled rooms within a building, the results of which can be used to improve office and residential environments.

Acoustics Modelling and Analysis

The laws of physics are typically described by partial differential equations (PDEs), where a dependent variable such as temperature, velocity or electric potential varies with respect to an independent variable, such as position or time. Analytical solutions to these equations are often only possible for the simplest geometries which, though mathematically rigorous, rarely reflect the reality of a practical design.

Modern computers provide a means of approximating solutions to these physical situations by employing numerical techniques, with the most common being Finite Element Analysis (FEA). A geometry of arbitrary complexity is spatially discretised by creating a mesh, containing nodes at which the dependent variables are solved. Basis functions are selected to represent a spatial variation in these variables, each scaled by piecewise weightings for a solution consistent with the underlying PDE. Boundary conditions are applied which represent the value of dependent variables at nodes or boundaries, for which a unique solution can then be derived.
The solution is an approximation and convergence will therefore depend on meeting a predefined criterion. A common approach is to define a maximum relative error in a dependent variable between solver iterations, of less than 0.1% for example. By using a finer mesh, or increasing the order of basis functions, the rate of convergence can be increased at the cost of computational time. In certain cases, it is necessary to refine the mesh where a steep gradient in the dependent variable is expected, for example when solving fluid velocity close to no-slip boundaries. A mesh refinement study can be conducted to gauge this effect in a similar manner to the relative error.
The aim of FEA software is to reduce the need for prototyping and experimentation in the design or optimisation of a device. COMSOL Multiphysics is the principal FEA modelling package used by Xi, for which Xi is a certified consultant and recognised internationally. COMSOL provides the capability to solve for stationary, frequency/time-dependent and modal problems across multiple physical domains including solid mechanics, acoustics and electromagnetics. By establishing an FEA model which reflects measured data, it is possible to develop a deeper understanding of a design or device, driving further optimisation and innovation.

Acoustics and Vibration Modelling and Analysis

Acoustics and vibration have a physical causal link which Xi can help explore via numerical modelling and analysis. Over a decade ago, Xi led the way in developing fully-coupled structural dynamics-acoustic models of large scale energy converting devices such as wind and tidal turbines. These initial models were focused on the identification of noise sources and the development of mitigations techniques.

Over the proceeding decade, the fully-coupled approach has been expanded to examine the performance of a range of products at all physical scales: from microscale transducer optimisation; to kilometre-scale offshore HVDC cable installation and its effect on the marine environment.

At all scales the central modelling principle is consistent: the structural dynamics are modelled; the surface acceleration of the structure imparts an acceleration on the fluid in an acoustic domain (e.g. air, water, etc); and sound is generated. Meanwhile, the mass and motion of the fluid domain also imparts a load on the structure thereby affecting its dynamics response. The model is therefore fully-coupled, i.e. the structure affects the acoustic domain and the acoustic domain affects the structure.
While the central fully-coupled premise is consistent across all models, the physical scale of the acoustic domain controls the modelling method. At physical scales where the wavelength is comparable to the size of the geometry, the acoustics can be modelled with a finite element analysis. However, when the physical scale is far greater that the wavelength of sound, other methods must be used, or couple with an FEA, such as boundary element method, ray trace or diffusion acoustics. At the small scale, such as in the case of hearing aid or mobile phone microphones, thermal and viscous acoustic losses should also be considered. Other physics can also be coupled to these models, such as electrostatics and fluid flow.

Xi has the expertise and experience to help research and development teams develop and implement the best simulation approach to acoustic and vibration modelling and analysis.

Xi has assisted clients in modelling Computational Fluid Dynamics (CFD) across a variety of projects and industries. Completing accurate CFD analysis requires a detailed understanding of the physics environment to ensure that the correct turbulence models and initial conditions are used in the modelling process.

Our solid understanding of CFD has allowed us to perform detailed analysis of fluid structure interactions in a range of settings: from analysis of marine tidal turbines; to wind flow over structural louvres. We have also designed pressure vessels, and performed pressure wave analysis to inform designs for blast walls and containment in the event of pressure vessel failure.

Microfluidic devices are used in a wide range of research and development activities as well as commercial contexts. In all cases, simulation can reduce the time and effort spent on fabrication and testing when many configurations are required.

Because of the complexity of fluidic and chemical systems, experimental designs must be very carefully planned. Simulation can help you focus on the things that matter, getting products to market faster and at less cost.

Microfluidic phenomena can be applied to a broad range of medical devices, from droplet formation in drug delivery to fluid flow in surgical catheters. Some of the most significant applications are in the development of in-vitro diagnostic devices, where microfluidics can transform a complex bench assay system into a compact device or Lab-on-a-Chip devices.
These allow for savings in lab space, reductions in sample and reagent volumes, and point-of-care diagnostics.

Microfluidics are a key component of many biological and chemical process systems, where the handling of fluids on small scales allows for enhanced process control and reduced reagent usage results in significantly less waste. The enhanced process control allows for the more efficient production of high-value, low-to-moderate volume products. Due to the small size of the channels, designers take advantage of well-controlled mixing and heat transfer processes. Simulation can help describe these for bespoke channel geometries and operating conditions.

We use COMSOL Multiphysics to help characterize single or multiphase flows in small channels. Xi can guide you through the unique physics of microfluidics and assist your development of novel microfluidic devices. Our skills allow us to simulate laminar, turbulent, and even high-speed Mach flows, Multiphase flows, diffusion and convection processes, and fluid-structure analyses which are common in such CFD studies.

The optimisation process can be applied to anything we simulate at Xi.

We use optimisation solvers for calculating optimal solutions to engineering problems and improve the design of products. We can optimise devices and processes that involve phenomena such as electromagnetics, structural mechanics, acoustics, fluid flow, heat transfer, vibration, MEMS devices and Multiphysics based challenges. The optimisation process can be used to improve the shape of a product, the materials used, its assembly and how it interacts with its environment.

The optimisation process is independent of the physics being modelled. If an objective can be stated, then we can optimise the device or process.

Optimisation can be applied to any engineering challenge, product, system or structure. Previous Xi projects include: optimisation of materials and geometry of a novel, cutting-edge electrostatic speaker to increase sound level and reduce low-end roll-off; optimisation of battery geometry to achieve cost savings in the manufacturing process; industrial-scale electric generators optimisation to reduce cogging forces and vibration, extend lifespan and reduce fatigue.

Whatever your market sector or technology, you can harness the power of the computer brain to determine what the best solution is for your desired outcome.

Using computers to iteratively test in the virtual world leads to an optimised product more quickly and affordably than the ‘traditional’ approach. Real-world models still need to be validated, but virtual testing means you build a lot less, saving time and money on fabrication, testing and associated analysis. With a properly parameterised and validated model, your computing power can be unleashed to deliver the true optimal solution.

Advanced simulation puts you ahead of the competition and, where designs have a wide array of choices to make—a so-called large variable space— optimisation is a must. Design optimisation with numerical simulation is the most cost-effective, efficient way to narrow variable space and greatly reduce the time to design finalisation. Xi’s optimisation expertise can improve the performance of your product, reduce risk of failure, help identify the best materials to use and minimise the amount of material needed for manufacture. Accelerate your design process by using optimisation today.

Whether in the development stages or in the setup of physical laboratory research facilities and production lines, modelling batteries can save an enormous amount of time, energy and money. Materials and manufacturing processes can be extremely expensive, but simulation can guide your organization in the right direction at lower cost, and get your product to market faster with higher reliability.

Modelling batteries requires different levels of detail depending on the purpose of the simulations. Xi can assist in building Equivalent Circuit Models (ECM) or 1D, 2D or 3D physics-based models of batteries in COMSOL Multiphysics. We can use this system to explore new geometries, material properties or micro-scale electrochemical processes, explain measured behaviour and optimise your battery design. By coupling these models to the electrical loads or thermal and stress behaviours, Xi can provide a holistic view to help improve your technology.

Finite element modelling can help you investigate and improve device performance by identifying the effects of individual design parameters on charge and discharge cycles. This can guide you in developing your laboratory research programme and gain a deeper understanding and validation of the system behaviour. Ultimately, this leads to optimized production-scale processes.

Xi’s experience covers numerous chemistries in both traditional liquid electrolyte as well as solid-state batteries. We have assisted battery manufacturers in improving their understanding of their product and accelerating their development timelines. We have worked on small, low-power applications such as consumer electronics and also on high-power automotive systems.

Our world-leading expertise in battery development modelling has allowed us to deliver models for major players in the industry. Whether you are looking at improvement to charge density or a higher level of understanding to accelerate the development of new technologies, Xi can help improve your batteries and move us all towards a low-carbon world.

Thermodynamics involves the generation of heat and its transport between different parts of physical or engineering systems. Over a large range of application areas, Xi has worked with clients to understand what heat sources and sinks are in their device, and the impact they have on how the device functions.

All kinds of physical and engineering systems– motors, refrigerators, computer chips– involve the generation and transport of heat– from chemical reactions, friction, sunshine and the wind. Sometimes heat must be removed as quickly as possible, such as in high-performance graphics cards. Other times, heat flow should be reduced as much as possible, such as in building insulation design.
Temperature can change material properties, structural geometries, electronic performance, or the rate of chemical reactions. Thermodynamic simulation lets you understand what effects these will have on your system before spending time and money on large numbers of design variants.

At Xi, we use COMSOL Multiphysics to visualize and make sense of complex heat flow patterns. By coupling COMSOL’s Heat Transfer Module with the Structural Mechanics, Computational Fluid Dynamics and AC/DC Modules, we can analyse a huge range of effects: the thermal expansion of building structures to determine if they might crack; the transport of heat in microfluidic chemical reactors and its impact product yield; the change of iron core magnetic properties in motors.

Recent improvements to radiative heat transfer calculations allow for much faster simulation of heat flux between complex-shaped objects. This may be negligible at low temperatures but, at high powers and elevated temperatures, they may become very significant. Many heat transfer problems involve all three heat transfer modes simultaneously – conduction, convection, radiation. At Xi, we understand the complex design considerations involved with such cases.

Micro Electro Mechanical Systems (MEMS) consist of micron scale components which interact with their surrounding environment as sensors, actuators or both. Classic examples of consumer MEMS devices include accelerometers, micromirrors and microphones. The technology continues to advance, with gravity sensing and biomedical devices emerging.

Xi has design experience with both electrostatic and piezoelectric signal transduction, for mass market and bespoke industrial applications. Relative to macro scale systems, the large surface area to volume ratios in MEMS increase the importance of electromagnetic and fluid dynamic effects. A multiphysics approach is therefore fundamental to the design of MEMS devices for which Xi has a proven track record in across physical domains and orders of scale.

The fabrication process for MEMS devices emerged from semiconductor techniques where thin layer deposition, photolithographic patterning and etch steps define the geometry. By selectively patterning and etching sacrificial layers it is possible to release mechanical structures which can form the basis of a transducer. An understanding of how this process flow affects structural topology and device behaviour can be critical to the manufacturability of a device.

MEMS geometries often demand a fully-coupled multiphysics approach, with the sensitivity of mechanical structures to both viscous damping and electrostatic spring softening being two common examples. Device reliability can be a significant concern but stiction, thermal cycling, shock and vibration can all be mitigated through simulation.

COMSOL Multiphysics is our principal modelling platform, which gives us the ability to solve for a range of physical domains including structural mechanics, acoustics, fluid dynamics and electromagnetics. We have extensive experience with all kinds of MEMS concerns: the use of shell or membrane elements to compute thin film mechanics; contact simulations for stress or stiction recovery analysis; fully-coupled electro-mechanics for pull-in and resonance extraction.


Xi has been using advanced computer simulation since its inception. Using COMSOL we have continued pushing the boundaries of what is possible through simulation. Xi works closely with COMSOL and is one of only five certified COMSOL consultants in the UK and one of less than eighty worldwide.

COMSOL Multiphysics® Certified Consultant

COMSOL Multiphysics® is a simulation platform that links different disciplines allowing Xi to simulate and predict the effects of many phenomena and processes. The electrostatic behaviour of headphone speaker drivers; the structural and acoustic response of wind turbines; the mechanical excitation of the drivetrain; Xi can explore any design challenge at any scale using simulation.

The capabilities of simulation are constantly evolving and Xi is at the forefront of these changes. We work closely with the COMSOL technical development team and often test new features and technics to push the software to its full potential. Xi simulations allow clients to test and explore new configurations and concepts efficiently and at a cost well below that of physical tests and experiments.

Our approach to modelling & simulation

Having real-world grounding is key to Xi’s success in simulation and modelling. Xi’s modelling team have hands-on engineering experience which is vital when accessing the validity of modelling outputs. Our philosophy is, where possible, to use actual physical measurements or other real-world data to improve accuracy and provide confidence in our models.

The Xi team comprises a strong group of multidisciplinary specialists, allowing us to work with a multitude of COMSOL modules. We are experts in applying design optimisation to a variety of sectors across all physical scales.

Our COMSOL expertise includes:
  • Structural dynamics, vibration, fatigue and robustness
  • Multibody dynamics used for example in drivetrains
  • Acoustics
  • Electromagnetics used in electrical motors and generators
  • Electrostatics used in touch screens and speakers
  • Piezoelectric and other MEMS devises
  • Computational Fluid Dynamics

We work with clients all over the world including Europe, North America, Asia and Africa. Our work is regularly presented at international conferences and published in peer-reviewed articles. We have won multiple awards and our work on electrostatics and acoustics has been published in NASA Tech Briefs.

Using SimScale software, Xi pushes the boundaries of what is possible with wind microclimate modelling and assessment. We work closely with SimScale to deliver accurate wind microclimate models to predict the environmental impact that proposed building developments might have on the surrounding areas. Our highly accurate models of real-life spaces ensure suitability for their intended use while meeting the pedestrian comfort and safety criteria.

What is SimScale

SimScale is the world’s first production-ready SaaS application for engineering simulation. The SimScale platform supports five types of physics:

  • Solid Mechanics
  • Fluid Dynamics
  • Thermodynamics
  • Particle analysis
  • Thermomechanics

The cloud-based SimScale platform allows our clients to virtually test performance, optimise durability or improve the efficiency of their design long before building a physical prototype. The platform combines an easy-to-use interface with a workflow-based approach for performing various analysis types, especially Finite Element Analysis (FEA), Computational Fluid Dynamics (CFD), and Thermal Simulation. The system is applicable across multiple industries: architecture, engineering, and construction; consumer goods; electronics; energy; aerospace; automotive, and more.

How It works

Users can upload their CAD model and have it displayed in 3D to set up their simulation and interact with it as they would with desktop CAD software. As soon as the simulation is complete, users can access the results on the platform or download them locally. By harnessing the power of the cloud for simulation, SimScale eliminates the hurdles that accompany traditional simulation tools: high installation costs, licensing fees, deployment of high-performance computing hardware, and required updates and maintenance. Users always have the latest version of SimScale.

Using Simscale for Wind Microclimate Modelling

Core to Xi’s wind microclimate modelling is the use of SimScale which employs a GPU-based solver that makes use of the Lattice Boltzmann Method (LBM). Large geometry models of the built environment are processed via the cloud on multiple parallel GPU-based computing resource. This delivers solutions in hours and minutes rather than days and weeks of traditional CFD (computational Fluid Dynamics) solvers. The innovative LBM techniques also allow for transient turbulence results, providing data around wind gusts and unsafe wind conditions.
In the assessment of a new development Xi starts the process by building 3D models of the development site. The models include features in the surrounding city incorporating buildings, topography and porous media such as trees. Depending on the assessment type the appropriate wind conditions for that specific area are applied and Xi can then model the wind conditions around the development. Typically, the wind microclimate will be assessed for pedestrian wind comfort using the Lawson Comfort and Lawson Safety Criteria.

Simscale Benefits

The techniques employed by SimScale’s CFD solvers provide remarkable improvements in solver time versus traditional CFD techniques. Assessing wind conditions in large city models can be 20 to 30 times faster than traditional techniques. This allows Xi to undertake a more thorough analysis: assessing different configurations, mitigation options and solving for greater resolutions of wind directions.
CFD results of wind speeds and wind comfort criteria in coloured heat maps provide a far higher level of detail than traditional point measurement in a wind tunnel. Combined with fast modelling, this approach provides a significant new opportunity in how wind microclimates are reviewed, reducing the time to design and improving the confidence that the eventual design is right.

SimScale and WindModelling Specialists

Our specialised team has extensive experience simulating complex wind microclimate models. By early involvement in a project, we can identify potential issues with pedestrian safety and comfort, suggest realistic solutions and provide support throughout your planning applications.

To bring a concept to prototype and production, Xi uses SolidWorks Computer Aided Design (CAD) software for the production of engineering drawings and 3D part files.

The capabilities of SolidWorks allow us to efficiently produce accurate models, realising ideas into physical parts. Xi’s engineering team have experience from the design development to the production phase at a range of scales from intricate plastic parts to heavy structural steel components. For all designs, we apply a practical engineering understanding to ensure workable and functional designs.

SolidWorks allows us to produce detailed engineering drawings, with which we can assist in sourcing and liaising with fabricators to support the production and final development. For smaller prototyping and proof of concepts Xi uses 3D Solidworks models to produce 3D additive (or 3D printed) parts using a range of Ultimaker 3D printers, CNC desktop milling and laser cutting.

We use the advanced SolidWorks Simulation package to directly simulate the material, physical behaviour and performance of the designed parts. A key element for this process is component optimisation, which allows refinement of designs by removing specific material where not needed, saving weight and reducing production costs.