Single physics vs. multiphysics simulation: The key differences

Key takeaways

• Single physics simulations focus on one physical effect at a time, like heat transfer or structural stress.

• Multiphysics simulations combine multiple domains, capturing how they influence each other in real-world systems.

• Everyday products — from coffee machines to wind turbines — are inherently multiphysics.

• Relying only on single physics leads to blind spots, longer design cycles, and higher risk of late-stage failures.

• Multiphysics simulations improve accuracy, reduce risk, and speed up innovation by reflecting reality more closely.

Introduction

Every engineered product interacts with the physical world in more ways than one. 

Heat, forces, electricity, and fluid flows often act together in ways that can’t be separated. Yet in many cases, simulations are still run in isolation, focusing on only one of these domains at a time.

This creates a gap between how we design and how things actually work in reality. 

Understanding the difference between single physics and multiphysics simulations is not just a matter of terminology—it determines how accurately engineers can predict performance, spot risks, and bring reliable products to market.

What is single physics simulation?

A single physics simulation models only one type of physical behavior at a time. 

It might be a thermal simulation that looks at how heat spreads through a material, or a structural simulation that measures how a beam bends under load. 

These models are useful because they isolate one effect and provide detailed insights into it.

The limitation is that single physics assumes the world can be neatly divided into separate boxes. 

In practice, heat changes the strength of materials, moving parts create friction that generates heat, and electromagnetic fields induce mechanical forces. 

When only one of these is modeled, the bigger picture is missing.

A simple example is airflow around a car. 

A single physics simulation can calculate drag and turbulence, but it won’t show how that airflow influences cooling systems or affects the temperature of structural parts. 

The model is correct within its own scope, but incomplete for the real system.

What is multiphysics simulation?

A multiphysics simulation combines several physical domains into one model so that their interactions are calculated together. 

Instead of looking at heat, forces, or electromagnetics separately, the solver couples them and tracks how each one influences the others.

This approach better reflects how real systems behave. 

For example, in an electric motor, electromagnetic fields generate torque, but also create heat. That heat changes material properties, which in turn alters mechanical stresses and efficiency. 

A single physics simulation would capture only one of these effects. A multiphysics simulation captures the full chain of interactions.

By modeling multiple domains at once, engineers can predict system behavior with higher accuracy and avoid surprises that emerge only when all effects come together in the real product.

Example of multiphysics in action: a piezoelectric micropump where mechanics, fluid flow, and electromagnetics interact.

Everyday examples of multiphysics

Examples of multiphysics are everywhere in daily life. 

A coffee machine is a simple case: electricity powers the heater, heat transfers into water, and fluid flow delivers the coffee. Each step depends on the others, and none of them can be understood in isolation.

A smartphone is another example. Its circuits generate electromagnetic fields that produce heat. That heat spreads through the materials, which expand and contract with temperature. Mechanical stresses build up, and long-term reliability depends on how these coupled effects play out.

On a larger scale, a wind turbine combines aerodynamics, structural mechanics, and electromagnetics. Wind applies forces to the blades, which bend and vibrate under load. The rotation generates electricity, which produces heating in the generator. The structural and electrical aspects cannot be separated if the goal is to predict performance over time.

These examples illustrate a simple point: real-world systems are inherently multiphysics. Treating them as single physics problems means ignoring critical parts of their behavior.

Limitations of single physics in practice

In engineering workflows, single physics simulations are often run in separate tools. 

A team might calculate thermal behavior in one program, structural stresses in another, and fluid dynamics in a third. 

Results are then transferred manually between models, sometimes with approximations or data loss along the way.

This creates several problems. 

Interactions between domains may be missed altogether, leading to designs that look sound in one analysis but fail under combined conditions. 

The process also slows development. Switching between tools and manually combining results increases turnaround times and reduces the number of design variations that can be tested.

The consequence is risk. Prototypes may reveal unexpected heating, vibrations, or stress points that were not captured in the simulations. 

Fixing these issues late in the process adds cost and delays, and in some cases, requires going back to the drawing board.

Why multiphysics matters for innovation

Designing new products always involves balancing performance, reliability, and speed of development. 

Multiphysics simulations make this process more efficient by capturing the real interactions between different physical effects from the beginning.

When those interactions are included, engineers reduce the chance of missing a critical failure mode. 

Heating that weakens materials, vibrations that amplify stresses, or electromagnetic effects that interfere with circuits can all be identified before a prototype is built. That reduces the likelihood of costly redesigns.

Multiphysics also accelerates development. 

Instead of switching between separate tools and combining results manually, engineers can test design ideas in a single environment. This makes it possible to explore more variations and optimize designs faster. 

In practice, this means higher-quality products can reach the market with fewer surprises and at lower cost.

The path forward

Engineering systems are only becoming more complex, and the demand for accurate and efficient simulation is growing. Multiphysics is not an optional extra, but the direction the entire field is moving toward.

Advances in solver technology and cloud computing have made multiphysics practical at scale. 

Engineers are no longer limited to workstation capacity or forced to split problems across multiple disconnected tools. 

Instead, full-system simulations can be run more quickly and on larger models than before.

At Quanscient, we built Allsolve from the ground up as a multiphysics platform. It was not added as an afterthought but designed to handle coupled physics as the default. 

This reflects the reality of how products behave and the way simulations need to be carried out in the future.

Conclusion

The physical world does not separate heat from mechanics, or fluid flow from electromagnetics. 

These effects happen together, shaping how products perform in reality. Simulations that focus on a single domain provide partial answers, but they cannot capture the complete picture.

Multiphysics simulation addresses this gap. By modeling interactions directly, it improves accuracy, reduces risks, and accelerates development. 

For engineers, this means fewer surprises during prototyping and more confidence in the final design.

The message is straightforward: the world is multiphysics, and in many cases, simulations need to be as well.

Learn more and get in touch now at quanscient.com

Frequently Asked Questions (FAQ)

 

What is multiphysics simulation?

Multiphysics simulation models several physical domains at the same time, such as thermal, structural, fluid, and electromagnetic effects, and calculates how they interact with one another.

How does multiphysics simulation differ from single physics?

Single physics simulations calculate only one physical effect, like airflow or structural stress, in isolation. Multiphysics simulations combine multiple effects, giving a more complete and accurate view of how a system will perform.

When should I run multiphysics simulations?

Multiphysics simulations are useful whenever different physical effects influence each other in a design. Typical cases include electric motors, MEMS devices, superconductors, and systems where heat, stress, and electromagnetic fields all interact.

Is multiphysics simulation more expensive or slower than single physics?

Traditionally, multiphysics simulations required more computing power and time than single physics. With advances in solvers and cloud computing, this barrier has been reduced significantly. Today, running multiphysics simulations at scale is practical and often faster than running multiple disconnected single physics models.

How does cloud computing change multiphysics simulation?

Cloud computing removes the hardware limits of local workstations. Engineers can run larger and more complex multiphysics models in parallel, explore many design variations at once, and access results faster. It also simplifies collaboration by making simulations accessible from anywhere.

What is the best multiphysics simulation software?

The best software depends on the problem being solved, but the trend is clear: modern solvers are moving toward cloud-native multiphysics as the default. Quanscient Allsolve was built from the ground up for this purpose, allowing coupled simulations to run efficiently at scale.