What Is Engineering Simulation—and What Can You Actually Simulate?

A CAD model tells you what a product is supposed to look like.

Engineering simulation tries to tell you what will happen to it.

Will that bracket bend?

Will air flow smoothly through that duct?

Will an electric motor overheat?

Will a bridge vibrate?

Will a battery cell become dangerously hot?

Will a vehicle suspension behave the way its designers intended?

Will a loudspeaker sound right?

Will an aircraft component survive repeated loading?

Those questions belong to the world of engineering simulation.

Modern simulation software allows engineers to build mathematical models of products, machines, structures and physical systems and then predict how those systems may behave before—or alongside—physical testing.

That can mean calculating stress in a simple metal part.

It can also mean simulating airflow, heat, vibration, electromagnetics and structural deformation together in one extremely complicated model.

So what exactly is engineering simulation, and what can engineers realistically simulate?

What Is Engineering Simulation?

Engineering simulation uses mathematical models and computer calculations to predict how a real-world product, component or system may behave under specified conditions.

The engineer begins with a model.

That may come from:

• a CAD system
• a simplified geometric model
• a system model
• measured data
• mathematical equations

The engineer then tells the simulation software something about the real-world conditions the model will experience.

Those inputs might include:

• forces
• pressure
• temperature
• airflow
• fluid velocity
• electrical current
• electromagnetic fields
• vibration
• material properties
• gravity
• contact between parts

The software solves mathematical equations representing the relevant physics and predicts how the model responds.

The result is not merely a colorful picture.

Depending on the simulation, engineers may obtain numerical predictions of:

• stress
• strain
• deformation
• temperature
• pressure
• velocity
• acceleration
• vibration
• fatigue life
• airflow
• heat transfer
• electromagnetic fields
• acoustic pressure
• fluid forces

Simulation lets engineers investigate physical behavior without having to manufacture and destroy a prototype every time they change the design.

Simulation Is Not the Same as CAD

CAD and simulation frequently work together, but they answer different questions.

CAD asks:

What should we design?

What does it look like?

How does it fit together?

How will it be manufactured?

Simulation asks:

Will it work?

Will it survive?

How will it behave?

What happens if conditions change?

Could we make it lighter, cooler, quieter or more efficient?

A CAD model might show a cooling fan perfectly mounted inside an electronics enclosure.

Simulation can help determine whether the fan actually moves enough air to prevent the electronics from overheating.

CAD can show an aircraft wing.

Simulation can help predict how the wing will deform under aerodynamic loading.

CAD defines geometry.

Simulation investigates behavior.

What Is CAE?

You will often see engineering simulation described as CAE, or Computer-Aided Engineering.

CAE is actually broader than any single simulation technique.

It includes engineering-analysis technologies such as:

• finite element analysis
• computational fluid dynamics
• thermal simulation
• multibody dynamics
• electromagnetics
• acoustics
• optimization
• system simulation

Simulation software from companies such as Ansys, Siemens, Altair, Dassault Systèmes, COMSOL, SimScale and Cadence can cover one or many of these disciplines.

What Is Finite Element Analysis?

Finite Element Analysis, usually called FEA, is one of the most widely used types of engineering simulation.

FEA predicts how structures and components behave when exposed to loads or other physical effects.

The software divides a complex object into many smaller pieces called finite elements.

Together, those elements form a mesh.

The software calculates how the elements respond to forces and how that behavior propagates through the complete structure.

Engineers use FEA to investigate questions such as:

• Where will this component experience the highest stress?
• How much will it bend?
• Will it permanently deform?
• Where might it fail?
• Can material be removed without compromising strength?
• What happens if the load increases?
• Will two parts remain in contact?

FEA can be used on something as simple as a mounting bracket or something as complicated as an aircraft fuselage.

What Can Structural Simulation Predict?

Structural simulation can examine far more than whether something simply breaks.

Stress

Stress describes the internal forces created within a material.

Engineers can identify regions where stress becomes excessive.

Strain

Strain describes how much a material changes shape relative to its original dimensions.

Deformation

Simulation can show how far a structure bends, stretches, compresses or twists.

Buckling

Thin or slender structures may suddenly become unstable under compression even before the material itself fails.

Simulation can help predict this behavior.

Contact

Assemblies contain parts that touch, slide, separate or press against one another.

Contact simulation is important for:

• gears
• seals
• bearings
• fasteners
• mechanical assemblies

Nonlinear Behavior

Some problems do not behave proportionally.

Examples include:

• rubber
• plastics
• large deformation
• changing contact
• material yielding

Advanced structural solvers such as Abaqus and Marc are particularly associated with these kinds of nonlinear problems.

What Is Computational Fluid Dynamics?

Computational Fluid Dynamics, or CFD, predicts the movement of liquids and gases.

Instead of building a physical wind tunnel or flow bench for every design change, engineers can create a virtual model of the fluid behavior.

CFD can help answer questions such as:

• How does air move over a vehicle?
• Where does aerodynamic drag originate?
• How does water move through a pump?
• Will airflow adequately cool an electronic device?
• How evenly does air move through an HVAC system?
• Where does turbulence develop?
• What happens inside a valve?

CFD software solves mathematical equations representing conservation of mass, momentum and energy.

You Can Simulate Air

Air is a fluid.

That means CFD can be used to model:

• aircraft aerodynamics
• race-car aerodynamics
• wind turbines
• cooling fans
• HVAC systems
• building ventilation
• drone propellers
• vehicle drag
• airflow around buildings

Engineers can examine:

• pressure
• velocity
• turbulence
• vortices
• lift
• drag

A wind tunnel remains extremely valuable.

But simulation lets engineers examine far more design variations before deciding which ones deserve physical testing.

You Can Simulate Water

The same basic principles apply to liquids.

CFD can help analyze:

• pumps
• valves
• piping
• ship hulls
• marine propellers
• cooling systems
• water treatment
• medical fluid devices

Marine engineers, for example, can simulate flow around a ship hull before building a physical model.

Pump designers can investigate cavitation and internal flow.

Medical-device engineers can study blood flow through a device.

The fluid does not have to be air.

You Can Simulate Heat

Thermal simulation predicts how heat moves through and around a product.

Engineers can model:

• conduction
• convection
• radiation

Consider a computer processor.

It generates heat.

That heat moves through the package and heat sink.

Air carries some of the heat away.

Radiation may also contribute.

Simulation can help determine whether the processor remains within an acceptable operating temperature.

Thermal simulation is important for:

• electronics
• batteries
• electric motors
• engines
• turbines
• spacecraft
• manufacturing processes
• HVAC

You Can Simulate Vibration

Everything has natural frequencies.

When an external force excites a structure near one of those frequencies, vibration can become severe.

Simulation can help predict:

• natural frequencies
• vibration modes
• resonance
• forced vibration
• random vibration

This matters for products ranging from aircraft and automobiles to washing machines and industrial machinery.

A component may be structurally strong enough to survive a static load but fail prematurely because of vibration.

You Can Simulate Fatigue

A component does not necessarily fail because one load is too large.

It may fail because a smaller load occurs thousands or millions of times.

This is fatigue.

Think of repeatedly bending a paper clip.

No single bend may break it.

Repeated bending eventually does.

Fatigue simulation helps engineers estimate how repeated loading affects product life.

Applications include:

• aircraft structures
• automotive components
• rotating machinery
• bridges
• offshore structures
• industrial equipment

You Can Simulate Crash and Impact

Some simulation problems happen extremely quickly.

Examples include:

• automotive crashes
• dropped electronics
• tool impacts
• projectile impacts
• packaging drops
• protective equipment

Explicit-dynamics solvers can model extremely nonlinear behavior occurring over short periods of time.

Instead of simply asking whether a structure is strong enough, engineers can investigate how it folds, crushes, fractures or absorbs energy during an event.

You Can Simulate Motion

Not all engineering simulation is about stress or fluids.

Multibody dynamics predicts how connected mechanical systems move.

Examples include:

• vehicle suspensions
• excavator mechanisms
• robots
• landing gear
• transmissions
• linkages
• industrial machinery

The simulation may model:

• joints
• springs
• dampers
• motors
• actuators
• contact
• flexible components

Software such as Adams and Simcenter Motion specializes in these types of problems.

You Can Simulate Sound

Acoustic simulation predicts how sound and pressure waves behave.

Engineers use acoustic simulation for:

• vehicle cabins
• aircraft interiors
• loudspeakers
• HVAC systems
• industrial equipment
• consumer products
• sonar
• medical devices

Acoustic problems frequently interact with other simulation disciplines.

A vibrating structure may produce sound.

Airflow may produce noise.

A loudspeaker involves electromagnetics, mechanical motion and acoustics.

This is where simulation begins to become multiphysics.

You Can Simulate Electromagnetics

Electromagnetic simulation predicts the behavior of electric and magnetic fields.

Applications include:

• antennas
• motors
• transformers
• sensors
• radar
• wireless systems
• electronics
• semiconductor devices

Engineers might investigate:

• electromagnetic interference
• antenna performance
• magnetic fields
• motor torque
• electrical losses
• RF propagation

Electromagnetic simulation becomes particularly interesting as products become increasingly electrified.

What Is Multiphysics Simulation?

The real world does not politely divide itself into separate engineering departments.

Physics interact.

That is what multiphysics simulation attempts to model.

Consider an electric motor.

Electromagnetic fields generate torque.

Electrical losses generate heat.

Heat changes material properties.

Cooling airflow removes some of that heat.

Mechanical rotation produces vibration.

Vibration produces noise.

You could analyze each phenomenon separately.

But eventually the engineer may need to understand how they influence one another.

Multiphysics simulation couples two or more physical domains.

Common combinations include:

• thermal + structural
• fluid + thermal
• electromagnetic + thermal
• fluid + structural
• structural + acoustic
• electromagnetic + mechanical

Modern platforms increasingly support workflows spanning several of these disciplines.

You Can Simulate Entire Systems

Simulation can also occur at a higher level than individual components.

System simulation represents the behavior of interconnected subsystems.

Instead of modeling every bolt and surface, engineers may create mathematical representations of things such as:

• engines
• batteries
• pumps
• motors
• hydraulic systems
• control systems

Those models interact to predict overall system behavior.

For example, an electric-vehicle system simulation might combine:

• battery behavior
• electric motor
• inverter
• cooling loop
• vehicle mass
• controls
• drive cycle

The purpose is not necessarily to calculate stress in every component.

It is to understand how the entire system behaves.

Can You Simulate Manufacturing?

Yes.

Simulation can also predict aspects of the manufacturing process itself.

Examples include:

• metal forming
• injection molding
• casting
• welding
• additive manufacturing
• machining
• composite manufacturing

Engineers can investigate questions such as:

• Will material fill the mold?
• Where will residual stress occur?
• Will a printed component distort?
• How will metal flow during forming?
• Where might a casting develop defects?

Simulation is therefore not limited to predicting how the final product behaves.

It can also help predict how the product gets made.

Can Simulation Replace Physical Testing?

Usually, no—and that is an important distinction.

Simulation is not automatically truth.

It is a mathematical prediction based on:

• the model
• assumptions
• material data
• boundary conditions
• mesh
• solver
• numerical settings

If those inputs are wrong, the simulation may also be wrong.

Simulation therefore works best as part of a broader engineering validation process.

Engineers compare simulation results with:

• physical testing
• analytical calculations
• experimental measurements
• known benchmark problems
• historical data

The more confidence engineers establish in the model, the more useful simulation becomes for exploring designs that have not yet been physically tested.

The Most Dangerous Simulation Is a Convincing Wrong One

Modern simulation software can produce beautiful images.

Stress contours.

Airflow streamlines.

Temperature gradients.

Pressure plots.

Animations.

Those visualizations can be extraordinarily persuasive.

That creates one of simulation’s greatest dangers.

A result can look completely reasonable and still be wrong.

Perhaps:

• the material property was wrong,
• a boundary condition was unrealistic,
• contact was defined incorrectly,
• the mesh was inadequate,
• turbulence was modeled badly,
• or the engineer simply asked the wrong question.

Simulation software does not eliminate the need for engineering judgment.

It often increases it.

Simulation Is Becoming Easier to Use

Historically, advanced simulation was often performed by dedicated specialists.

That is changing.

Modern tools increasingly offer:

• automatic meshing
• cloud computing
• automated workflows
• CAD-integrated simulation
• guided setup
• optimization
• reduced-order models
• AI-assisted simulation

Cloud platforms such as SimScale allow CFD, FEA, thermal and electromagnetic simulations to be run through a browser.

Major simulation platforms are also integrating AI to help automate model setup and accelerate predictions.

This could make simulation available to far more engineers.

But easier access creates another challenge.

Making simulation easier to operate does not necessarily make the underlying physics easier to understand.

That distinction is going to become increasingly important.

What Software Do Engineers Use for Simulation?

There is no single best simulation program.

Different products emphasize different engineering disciplines and workflows.

Major platforms include:

Ansys

One of the broadest simulation portfolios, covering structural analysis, CFD, electromagnetics, thermal simulation, system simulation and many specialized physics disciplines.

Siemens Simcenter

A broad simulation and test portfolio covering structural, fluid, thermal, acoustic, electromagnetic and system simulation.

Siemens is also integrating technology acquired with Altair into the Simcenter portfolio.

Altair

Now part of Siemens, Altair technologies include structural analysis, optimization, explicit dynamics, CFD, electromagnetics, multibody dynamics and HPC.

Many Altair products are being incorporated and renamed within Simcenter.

COMSOL Multiphysics

Designed around coupled physics and flexible mathematical modeling.

Particularly attractive when multiple physical phenomena strongly interact.

Abaqus / SIMULIA

Dassault Systèmes’ simulation portfolio, with Abaqus particularly well known for advanced nonlinear FEA, contact, material behavior and explicit dynamics.

SimScale

A cloud-native simulation platform offering CFD, FEA, thermal, electromagnetics and multiphysics through a web browser.

MSC Software / Cadence

The MSC portfolio includes MSC Nastran, Adams, Marc, Actran, Cradle CFD and other specialized simulation technologies.

MSC Software became part of Cadence in 2026.

Which Type of Simulation Do You Need?

A useful starting point is the engineering question itself.

If you’re asking:

Will it bend, break or deform?
Start with structural FEA.

How will air or liquid flow?
Look at CFD.

Will it get too hot?
Look at thermal simulation.

How will a mechanism move?
Look at multibody dynamics.

Will repeated loading cause failure?
Look at fatigue analysis.

How will it behave during impact or crash?
Look at explicit dynamics.

Will it vibrate?
Look at structural dynamics.

How loud will it be?
Look at acoustics.

How will electromagnetic fields behave?
Look at electromagnetic simulation.

Do several of these things affect one another?
You may need multiphysics simulation.

Do you need to understand the behavior of an entire interconnected product?
You may need system simulation.

What Should You Look for When Evaluating Simulation Software?

The longest feature list does not necessarily identify the best simulation platform.

During a trial, evaluate:

• whether it supports the physics you actually need
• CAD interoperability
• meshing
• solver accuracy
• convergence
• performance
• post-processing
• workflow automation
• cloud or HPC requirements
• collaboration
• licensing
• pricing
• learning curve
• product roadmap

Most importantly, use a representative engineering problem.

Do not judge simulation software only from vendor-provided tutorials.

A tutorial is designed to work.

Your engineering problem is what matters.

Download the Simulation Software Trial Scorecard

If you are comparing simulation platforms, use our Simulation Software Trial Scorecard to evaluate technical fit, trial accessibility, validation, licensing, pricing transparency and evaluation investment risk.

The scorecard separates technical capability from trial friendliness so that an inconvenient evaluation process does not automatically make technically excellent simulation software appear inferior—and an easy free trial does not disguise a solver that fails your engineering requirements.

Engineering Simulation Is Really About Asking “What If?”

CAD lets engineers create something that does not yet exist.

Simulation lets them ask what might happen to it.

What if the material changes?

What if the load doubles?

What if airflow drops?

What if the ambient temperature rises?

What if the wall becomes thinner?

What if the motor spins faster?

What if the component is made lighter?

What if two physical effects happen at the same time?

Not every simulated answer will be correct.

Not every model will represent reality perfectly.

Physical testing will remain essential.

But simulation gives engineers something extraordinarily powerful:

the ability to explore consequences before those consequences exist in the physical world.

That is why engineering simulation has become such an important part of modern product development.