Demystifying CFD: A Guide to 10 Leading Solvers for Product Design

Computational Fluid Dynamics (CFD) has transformed product design and development across industries. By digitally simulating the complex physics of fluid flows, heat transfer and associated phenomena, CFD empowers engineers to accurately predict performance, tackle issues, and optimize designs – before expensive physical prototyping.

This enables informed design decisions to be made faster, with less money invested. In an era of compressed development timelines, CFD delivers immense competitive advantage.

The global CFD market has expanded at a CAGR of 6.7% to be worth $2.4 billion in 2022. Growth drivers include:

  • Need to accelerate innovation by frontloading digital validation
  • Integration of CFD with wind tunnel and on-road testing programs
  • Democratization of simulation through cloud computing

With products ranging from aircrafts and GPUs to insulin pumps involving fluids and heat management, CFD‘s applicability is limitless. Its permeating integration with the product design process makes selecting the right software more crucial than ever.

This guide will equip you to make this important decision by:

  • Demystifying CFD workflow & physics simulation
  • Overviewing 10 leading commercial and open source options across key metrics
  • Discussing technical factors that serve as selection criteria

So let‘s get started!

How Does CFD Software Work?

At its core, CFD leverages numerical analysis methods to predict fluid flows by solving the Navier-Stokes equations that govern fluid motion. The key steps in a CFD workflow are:

1. Pre-Processing

This involves modeling the specific problem‘s geometry, fluid physics, material properties and boundary conditions. Solver settings are configured based on required accuracy.

The volume occupied by fluid is discretized into a mesh of cells. Meshing types include:

  • Tetrahedral mesh – Accurately represents complex geometry but less accurate for fluid flow
  • Polyhedral mesh – Computationally more efficient for CFD analysis

2. Solving

Governing fluid flow partial differential equations are converted to algebraic forms and solved iteratively. Widely used numerical methods include:

  • Finite Volume Method (FVM) – Divides space into discrete control volumes and conserves relevant quantities
  • Finite Element Methods (FEM) – Divides geometry into elements and minimizes error in solution

Powerful solvers leverage high performance computing for fast, accurate simulations.

3. Post-Processing

Here the computed raw data is transformed to visualizations like velocity vectors, animations and graphs to convey insights. Simulation data can also be interfaced with optimization loops to automatically refine designs.

Physics Simulated in CFD

Sophisticated CFD software can model diverse phenomena relevant to product design:

Fluid Dynamics

  • Compressible/Incompressible
  • Turbulent Flow – RANS, LES, DES
  • Multiphase Flow – VOF, DEM, Eulerian
  • Non-Newtonian Flow – Carreau, Power Law
  • Free Surface Tracking
  • Porous Media Flow
  • Acoustics – CAA

Heat Transfer

  • Conduction
  • Convection
  • Thermal Radiation

Reaction Engineering

  • Species Transport
  • Chemical Reactions

This provides engineers immense physics flexibility to tackle real-world design complexity. Let‘s now overview top CFD tools available.

1. OpenFOAM: Open Source Powerhouse

OpenFOAM from the OpenFOAM Foundation is the leading free, open source CFD software. With a community of over 20,000 users across most science and technology domains, OpenFOAM offers unmatched capabilities.

Key Features

  • Extensive Physics – Over 80 pre-coded solvers for complex phenomena related to chemistry, electromagnetics, heat transfer, stress analysis and more
  • Parallel Processing – Inbuilt support for simulation using MPI and domain decomposition
  • Customization – Ability to extend functionality by modifying existing solvers and models or adding new ones using C++ coding

The main downside is OpenFOAM‘s steep learning curve. Being open source, documentation can also be lacking. But Global majors like GM, Honda and Caterpillar all use OpenFOAM – speaking to its production-grade robustness.

Software choice often presents a flexibility vs usability tradeoff. OpenFOAM delivers the ultimate in flexibility and control – provided users have the expertise to leverage it.

2. ANSYS Fluent: The Gold Standard

ANSYS Fluent is widely considered the most powerful commercial CFD workflow – reflected in its estimated 60% market share. Fluent leads across aerospace, automotive, energy and other sectors due to unparalleled physics modeling capabilities.

Key Highlights

  • Advanced Physics – Unmatched range of computational fluid dynamics capabilities covering aerodynamics, aeroacoustics, multiphase flows, heat transfer, electromagnetics and more
  • Customization – User defined functions (UDFs) to program custom models and boundary conditions tailored to specialized simulations
  • Multiphysics – Bi-directional coupling with ANSYS structural, electromagnetic and other solvers enables system-level analysis
  • Automation – Custom workflows possible by embedding optimization in simulation process enables automated, CFD-driven design improvement

ANSYS Fluent‘s depth of physics and customization comes at the expense of ease-of-use – expect a steep learning curve. But global giants like Airbus, GM, GE, Boeing and Shell all leverage Fluent‘s power – making it the CFD industry benchmark.

Need cutting-edge physics flexibility? Fluent delivers this better than any other solver.

3. Convergent Science: Specialized Powerhouse

While ANSYS targets CFD generalists, Convergent Science fulfills extreme physics depth needs – but for niche applications.

It specializes in transient flows and chemical reactions in complex, moving geometries – making it ideal for internal combustion (IC) engines:

Convergent CFD for Engine Design

Convergent‘s CFD engine model featuring dynamic meshing. Credit: Convergent Science

Key Capabilities

  • Advanced moving mesh capabilities through domain mirroring and interpolation for piston and valves
  • Multi-zone overset meshing for multiple moving parts without approximation losses
  • Detailed chemistry and spray modeling – leveraged by leading combustion research teams
  • GPU-acceleration of solver for faster turnaround

Convergent Science shows that moving beyond one-size-fits-all tools allows unmatched depth for focused applications. Specialization pays dividends.

For advanced research and design needs in IC engines, Convergent Science has no equal. Over 25 automotive and off-highway OEMs use their solver – including CAT, CNH, Ford and GM.

4. Siemens Simcenter STAR-CCM+ : The Automotive Specialist

Siemens CFD powerhouse Simcenter STAR-CCM+ offers a complete multiphysics workflow – seeing broad adoption across the Automotive sector.

Siemens CFD for Automotive Design

Automotive aerodynamic analysis using Simcenter STAR-CCM+. Credit: Siemens Software

Key Features

  • Automated meshing tools ensure quality discretizations with minimal user effort
  • CAD associativity automatically updates simulation geometry if native CAD model changes
  • Overset and dynamic mesh motion techniques handle complex moving parts
  • Conjugate heat transfer, reacting flows and electromagnetics modeling combine multiple phenomena

Siemens also offers the PowerFLOW suite – a specialized solver for ultra-accurate aerodynamic modeling using Lattice-Boltzmann methods.

Over 75% of automotive OEMs and top motorsport teams use Simcenter STAR-CCM+ to speed up design cycles. Its automated workflow also lowers barriers to applying simulation upfront.

If specialized automotive aerodynamics is your goal, few CFD solutions match Simcenter STAR-CCM+.

5. Altair UltraFluidX: The Electronics Cooling Specialist

While most CFD software cover fluid flows generically, some specialize in tailored workflows for specific applications.

UltraFluidX from Altair focuses exclusively on electronics cooling – spanning chip to facility-level thermal management.

Altair UltraFluidX Electronics Cooling

Datacenter CFD modeling using UltraFluidX. Credit: Altair

Key Capabilities

  • Electronics-specific modeling – simplifies modeling complex electronics assemblies
  • Conjugate heat transfer – combines fluid flow, heat conduction and radiation to simulate full thermal environment
  • Compact modeling – leverages simulation data to rapidly create reduced-order models (ROM) for faster design studies

By specializing, UltraFluidX offers tailored electronics cooling capabilities exceeding generic CFD tools. Top computing and consumer electronics giants like Amazon, HPE, Nintendo and more run UltraFluidX for designing their products.

For specialized electronics cooling needs, UltraFluidX delivers an unmatched combination of power and ease-of-use.

Cloud vs On-Premise: Best Environments for CFD

Since CFD solves computationally intensive physics simulations, solution time is dictated significantly by available computing hardware.

Traditionally most companies invested in on-premise high performance computing (HPC) clusters purpose-built to run CFD workflows. However, maintaining data centers incurs high capital and operational expenses.

The rise of cloud computing over the past decade has transformed data infrastructure strategies across industries – CFD is no exception.

According to analyst firm Everest Group: "Adoption of cloud-hosted CFD simulation services has increased 200%-300% since 2018".

Cloud offers enterprises key advantages:

  • Reduced IT infrastructure costs by over 40%
  • Flexibility to scale simulation needs instantly
  • Improved collaboration through hosted tools

Recognizing this trend of distributed resource usage, many CFD software now offer cloud-based delivery models. Let‘s discuss leading options.

6. SimScale – Cloud Disruptor for Occasional Users

SimScale offers a 100% browser-based suite to instantly setup and run CFD simulations. By fully embracing cloud delivery, they simplify access for casual users.

SimScale Cloud-Based CFD Platform

SimScale‘s Intuitive Cloud Workflow. Image Credit: SimScale

Key Attributes

  • Intuitive drag and drop user interface to minimize learning curve barriers
  • Secure cloud workspaces facilitate data and model sharing across teams
  • Flexible solving via on-demand compute resources – including GPU hardware
  • Low-cost subscription plans start under $100/month

By eliminating infrastructure management, SimScale makes CFD more accessible to organizations without existing simulation expertise. With over 60,000 users ranging from startups to Fortune 500 companies, this innovative platform leads CFD cloud democratization.

For companies with previously limited simulation usage, SimScale‘s simplicity and affordability provide the perfect cloud entry pathway.

7. Rescale – Cloud Built for Expert Users

At the other end of the spectrum, Rescale offers a high-performance cloud infrastructure tailored to advanced expert requirements.

Rescale Cloud HPC Infrastructure

Rescale‘s Tailored Cloud HPC. Image Credit: Rescale

Key Features

  • Optimized integration with leading CFD applications like ANSYS Fluent, STAR-CCM+, OpenFOAM etc
  • Flexible HPC cluster provisioning from world‘s fastest CPU, GPU hardware
  • Global availability – launch CFD jobs closest to your location
  • Custom engineering collaboration tools

By matching on-premise cluster performance, Rescale makes public cloud infrastructure viable for traditional supercomputing applications – CFD foremost among them. Their specialized capabilities have garnered customers like SpaceX, Boeing,BARDA and the US Army.

If maximizing simulation productivity for expert users is the goal, Rescale delivers cutting-edge STAR-CCM+ an unmatched cloud experience.

Additional Evaluation Criteria

Beyond pure physics modeling capabilities, additional factors matter while selecting CFD software:

1. Available Computational Budget

  • Open source software like OpenFOAM have no licensing fees but require own infrastructure
  • Cloud options like SimScale and Rescale charge rent-by-the-hour based on compute resource usage
  • Perpetual licenses for tools like ANSYS Fluent start around $45,000 per license

Carefully evaluate tradeoffs to pick the optimal price/performance.

2. Ease-of-Use

  • Open source flexibility comes at the cost of steep learning curves
  • Commercial providers like SimScale invest heavily in intuitive interfaces to lower barrier to adoption
  • Evaluating documentation quality and available training is crucial

3. Technical Support Responsiveness

  • Rescale, SimScale and enterprise modeling experts like Altair and ANSYS offer reliable, US-based technical support teams available promptly by phone and email.
  • Community forums serve as unofficial support channels for open source projects

Think through factors like these during CFD software evaluation. Every product development organization has unique constraints – identify Needs Before Proceeding to a purchase decision.

Concluding Thoughts

This guide has aimed to provide a 360-degree perspective on the global CFD landscape – spanning leading physics engines, cloud vs on-premise tradeoffs and other decision drivers.

While computing power has improved immensely over the past decades, technology alone cannot drive impact. True leverage comes from matching sophisticated tools to specific goals and constraints. I hope framing CFD software evaluation across technical capability, cost, usability and support factors helps identify the optimal choice for your needs.

Lastly, don‘t view software selection as a one-time activity. Constant innovation means solutions must adapt constantly to stay relevant. Moving to the cloud or augmenting with AI-driven automation are examples of future directions. Stay nimble and open to change.

The democratization marches on! Please reach out with any questions.