Multi-Physics Simulation Methods

Understanding Multi-Physics Simulation: A Comprehensive Overview

In today's increasingly complex engineering landscape, the ability to analyse multiple physical phenomena simultaneously has become essential for developing robust, efficient designs. Multi-physics simulation methods represent a sophisticated approach to engineering analysis that considers the intricate interactions between different physical domains—thermal, structural, fluid, electromagnetic, and chemical—within a single computational framework.

For engineering firms operating in Atlantic Canada, where projects range from offshore energy installations battling harsh marine environments to advanced manufacturing facilities requiring precise thermal management, multi-physics simulation provides the analytical depth necessary to ensure designs perform reliably under real-world conditions. The Maritime provinces present unique engineering challenges, from extreme temperature variations between seasons to the corrosive effects of salt-laden air, making comprehensive simulation approaches particularly valuable.

Traditional single-physics analyses, while still valuable for many applications, often fall short when dealing with systems where multiple physical phenomena interact and influence one another. A heat exchanger's structural integrity, for example, cannot be fully understood without considering thermal expansion, fluid pressure, and potentially vibration-induced fatigue simultaneously. Multi-physics simulation bridges these analytical gaps, providing engineers with a more complete picture of system behaviour.

Core Physical Domains in Multi-Physics Analysis

Multi-physics simulation encompasses several fundamental physical domains, each governed by distinct mathematical equations and physical principles. Understanding these domains and their interactions forms the foundation of effective coupled analysis.

Structural Mechanics

Structural analysis examines how components deform and stress under applied loads. In multi-physics contexts, structural behaviour couples with thermal expansion, fluid pressure loading, and electromagnetic forces. Modern finite element solvers can handle linear and nonlinear material behaviour, contact mechanics, and dynamic response with time steps as fine as microseconds for impact analysis or vibration studies.

Computational Fluid Dynamics (CFD)

CFD solves the Navier-Stokes equations to predict fluid flow patterns, pressure distributions, and turbulence characteristics. Reynolds numbers in industrial applications can range from laminar flows below 2,300 to highly turbulent conditions exceeding 100,000, requiring different turbulence models such as k-epsilon, k-omega SST, or Large Eddy Simulation (LES) approaches. For Nova Scotia's fishing and aquaculture industries, CFD analysis of vessel hulls and underwater equipment proves particularly relevant.

Heat Transfer

Thermal analysis addresses conduction, convection, and radiation heat transfer mechanisms. Coupled thermal-structural simulations are essential for equipment operating across the temperature ranges experienced in Atlantic Canada, where ambient conditions can vary from -30°C in winter to +35°C in summer—a 65°C range that induces significant thermal stresses in many engineering materials.

Electromagnetics

Electromagnetic simulation covers static and dynamic electric and magnetic fields, electromagnetic wave propagation, and induced currents. This domain becomes critical when analysing motors, generators, transformers, and electronic systems, particularly for the growing renewable energy sector in the Maritimes.

Coupling Strategies and Methodologies

The manner in which different physical domains exchange information significantly impacts both accuracy and computational efficiency. Engineers must select appropriate coupling strategies based on the strength of physical interactions and available computational resources.

One-Way Coupling

In weakly coupled systems, one physical domain influences another without significant feedback. For example, analysing thermal stresses in a component where temperature changes minimally affect the thermal solution itself represents one-way coupling. This approach reduces computational requirements—often by 40-60% compared to full coupling—while maintaining acceptable accuracy for many practical applications.

Two-Way (Bidirectional) Coupling

Strong physical interactions require two-way coupling, where both domains continuously exchange information. Fluid-structure interaction (FSI) exemplifies this approach: fluid pressure deforms a structure, which in turn alters the flow field, changing the pressure distribution. Convergence typically requires 5-15 iterations per time step, depending on the coupling strength and relaxation parameters employed.

Sequential vs. Simultaneous Solving

Sequential (partitioned) approaches solve each physics domain separately, exchanging boundary conditions between solutions. This method leverages existing single-physics solvers and offers flexibility but may require small time steps for stability. Simultaneous (monolithic) approaches solve all equations together in a single matrix system, providing better stability for strongly coupled problems but requiring specialised solver development and significantly more memory—often 3-5 times more than partitioned approaches.

For most industrial applications encountered in Maritime engineering projects, partitioned approaches with appropriate stabilisation techniques offer the best balance of accuracy, flexibility, and computational efficiency. Time step sizes typically range from 0.001 to 0.1 seconds for transient analyses, depending on the fastest physical phenomena being captured.

Industrial Applications in Atlantic Canada

Multi-physics simulation addresses numerous engineering challenges across industries prevalent in Nova Scotia and the broader Atlantic region. The following examples illustrate practical applications where coupled analysis delivers significant value.

Marine and Offshore Engineering

Atlantic Canada's extensive coastline and growing offshore energy sector create substantial demand for marine engineering expertise. Multi-physics simulation supports:

• Wave-structure interaction analysis for offshore platforms, predicting dynamic loads from waves up to 15 metres in height during severe storms

• Corrosion-fatigue assessment coupling electrochemical models with structural fatigue analysis, critical for structures in seawater environments where corrosion rates can reach 0.1-0.3 mm per year

• Ice-structure interaction for operations in areas experiencing seasonal ice, requiring coupled thermal-mechanical models

• Propulsion system optimisation involving fluid-thermal-structural coupling in marine engines and thrusters

Energy Sector Applications

Nova Scotia's commitment to renewable energy, including wind and tidal power development, presents unique multi-physics challenges:

• Wind turbine blade analysis combining aerodynamic loading, structural response, and fatigue assessment across operational wind speeds from 3 to 25 m/s

• Tidal turbine design in the Bay of Fundy, home to the world's highest tides exceeding 16 metres, requiring coupled fluid-structural analysis under extreme flow conditions with velocities reaching 5 m/s

• Power electronics thermal management coupling electromagnetic losses with conjugate heat transfer analysis to maintain junction temperatures below 125°C

Manufacturing and Process Industries

The region's manufacturing sector benefits from multi-physics simulation in numerous ways:

• Welding simulation coupling thermal, metallurgical, and mechanical phenomena to predict residual stresses and distortion

• Injection moulding analysis combining fluid flow, heat transfer, and structural mechanics to optimise cycle times and part quality

• Industrial heat exchanger design requiring conjugate heat transfer with structural assessment under operating pressures exceeding 1,000 kPa

Software Platforms and Computational Considerations

Implementing multi-physics simulation requires appropriate software tools and computational infrastructure. Several commercial and open-source platforms serve the engineering community, each with distinct strengths.

Commercial Software Solutions

Leading commercial platforms include ANSYS Workbench, which provides seamless coupling between structural, thermal, fluid, and electromagnetic solvers; COMSOL Multiphysics, known for its flexibility in defining custom coupled equations; and Siemens Simcenter, offering comprehensive multi-domain capabilities. Licensing costs for these platforms typically range from $15,000 to $80,000 CAD annually, depending on module selection and solver capabilities.

Open-Source Alternatives

Open-source options like OpenFOAM (CFD), CalculiX (structural), and Elmer (multi-physics) provide capable alternatives for organisations with appropriate technical expertise. While eliminating licensing costs, these tools require greater investment in user training and workflow development.

Hardware Requirements

Multi-physics simulations demand substantial computational resources. Typical requirements for industrial-scale models include:

• Memory: 64-256 GB RAM for models with 5-20 million degrees of freedom

• Processing: 16-64 CPU cores for reasonable solution times

• Storage: 500 GB to several terabytes for transient analyses with multiple saved time steps

• Solution times: Complex coupled analyses may require 12-72 hours of computation, making high-performance computing clusters advantageous for design iteration studies

Cloud computing platforms increasingly offer viable alternatives to on-premises hardware, with providers offering engineering-optimised instances featuring high memory bandwidth and parallel processing capabilities. This approach proves particularly attractive for firms in Atlantic Canada seeking to minimise capital expenditure while maintaining access to substantial computational resources.

Best Practices for Successful Implementation

Achieving reliable results from multi-physics simulation requires careful attention to modelling practices, validation approaches, and project management considerations.

Model Development Guidelines

Effective multi-physics models begin with clear definition of the physical phenomena requiring analysis and their expected interaction strengths. Engineers should:

• Start with simplified models to verify coupling behaviour before adding geometric and physical complexity

• Use consistent mesh densities across physical domains, with element sizes appropriate for the shortest wavelength or steepest gradient expected

• Apply appropriate boundary conditions that accurately represent the physical environment, including ambient temperatures, convection coefficients, and fluid inlet conditions

• Conduct mesh sensitivity studies, typically requiring 3-5 mesh refinement levels, to ensure solution independence from discretisation

Validation and Verification

Confidence in simulation results demands rigorous validation against experimental data or analytical solutions where available. For coupled problems, validation should address each physical domain individually before assessing coupled behaviour. Acceptable agreement between simulation and experimental results typically falls within 5-15% for engineering quantities of interest, depending on measurement uncertainty and model fidelity.

Documentation and Quality Assurance

Professional engineering practice requires thorough documentation of simulation assumptions, boundary conditions, material properties, and solver settings. This documentation supports peer review, facilitates design iterations, and maintains traceability for regulatory submissions. Canadian engineering standards emphasise the importance of documented verification and validation for computer-aided analyses used in design decisions.

Future Trends and Emerging Technologies

The field of multi-physics simulation continues evolving rapidly, with several trends poised to enhance capabilities available to engineering practitioners.

Machine Learning Integration

Artificial intelligence and machine learning techniques increasingly augment traditional physics-based simulation. Surrogate models trained on simulation databases can provide rapid approximate solutions—often 1,000 to 10,000 times faster than full physics models—enabling real-time design exploration and optimisation studies previously impractical due to computational costs.

Digital Twin Development

Multi-physics simulation forms the analytical foundation for digital twin implementations, where virtual models continuously reflect physical asset conditions through sensor data integration. This approach supports predictive maintenance, operational optimisation, and lifecycle management—capabilities increasingly valuable for infrastructure and equipment throughout Atlantic Canada.

Multiscale Modelling

Emerging methods bridge molecular, microscale, and macroscale phenomena within unified frameworks. These approaches prove essential for advanced materials development, including composites and nanomaterials, where bulk properties depend on microstructural characteristics.

Partner with Sangster Engineering Ltd. for Your Multi-Physics Simulation Needs

Successfully implementing multi-physics simulation requires not only sophisticated software tools but also deep engineering expertise to formulate appropriate models, interpret results, and translate findings into practical design improvements. The complexity of coupled analyses demands experienced practitioners who understand both the underlying physics and the numerical methods employed.

Sangster Engineering Ltd., based in Amherst, Nova Scotia, provides professional engineering services throughout Atlantic Canada, bringing analytical expertise to projects across multiple industries. Our team understands the unique challenges facing Maritime engineering projects—from extreme environmental conditions to the practical constraints of regional manufacturing capabilities.

Whether you require thermal-structural analysis for equipment operating in harsh coastal environments, fluid-structure interaction studies for marine applications, or coupled electromagnetic-thermal assessment for electrical systems, our engineers deliver the rigorous analysis your projects demand.

Contact Sangster Engineering Ltd. today to discuss how multi-physics simulation can enhance your product development process, reduce prototype testing costs, and improve design reliability. Let our expertise in advanced engineering analysis support your next project's success.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.