Freelance Cfd Simulation Engineer Jobs in Chicago, IL

The UL Solutions Research and Development team and Modeling and Simulation team is seeking a Simulation Engineer with a strong CFD, fire dynamics and thermal sciences background to support fire and explosion hazard modeling. This role applies advanced computational fluid dynamics, heat transfer, and combustion modeling to evaluate battery fires, gas explosions, and performance-based fire safety designs.
The engineer will primarily work with Flame Acceleration Simulator (FLACS) for deflagration explosion and gas dispersion analysis and Fire Dynamics Simulator (FDS), fire dynamics, smoke, and thermal impact modeling. The position supports large-scale battery fire testing, performance-based design (PBD), code compliance, and customer-facing engineering projects within the energy and built-environment sectors.
This role is intended for engineers trained in thermal-fluid sciences or CFD, who wish to specialize in fire and explosion safety engineering.
Responsibilities

• Develop and execute CFD-based fire and explosion simulations using:
  • FLACS for gas dispersion, flame acceleration, and vented/unvented deflagration analysis
  • FDS for gas dispersion, fire dynamics, smoke movement, heat transfer, and plume behavior
• Model ESS/BESS fire and explosion scenarios, including:
  • Battery off-gas release and dispersion
  • Ignition and overpressure development
  • Large-scale enclosure and outdoor fire scenarios
  • Apply strong fundamentals in heat transfer (convection, conduction, radiation), fluid flow and turbulence, combustion, and fire dynamics
• Analyze simulation outputs such as:
  • Temperature fields, heat fluxes, and thermal exposure
  • Overpressure and impulse
  • Gas concentration and visibility
• Support performance-based fire and explosion safety design (PBD) aligned with applicable codes and standards
• Interpret simulation results in the context of code intent, safety objectives, and risk reduction strategies
• Assist in defining credible worst-case and design fire/explosion scenarios
• Perform pre-processing, solver execution, and post-processing of CFD simulations
• Support verification and validation (V&V) through comparison with:
  • Large-scale ESS fire test data
  • Literature and experimental benchmarks
• Prepare clear, defensible technical reports for internal review and external customers
• Work under guidance of senior fire and explosion engineers while progressively taking ownership of tasks
• Collaborate with multidisciplinary teams across CFD, testing, certification, and research
• Maintain high-quality documentation and adherence to established modeling workflows
• Actively develop expertise by reviewing technical literature and internal best practices

Qualifications

• Bachelor's or Master's degree in Mechanical Engineering / Chemical Engineering/ Thermal Sciences/ Combustion, Fire Protection Engineering, or CFD-related disciplines
• 3-5 years of experience in CFD, thermal-fluid simulation, fire modeling, or related applied simulation work
• Hands-on experience or project exposure to:
  • Fire Dynamics Simulator (FDS) and
  • FLACS or similar explosion / gas dispersion tools
  • Computer Aided Design (CAD) software (e.g. Inventor, SolidWorks)
• Ability to apply engineering judgment and first principles when building simulation models
• Excellent technical writing and verbal communication skills
• Comfortable working independently on defined tasks within a structured engineering framework
• Exposure to battery energy storage systems (BESS/ESS) or lithium-ion thermal runaway (nice to have)
• Familiarity with large-scale fire testing or fire test data interpretation (nice to have)
• Awareness of performance-based fire engineering concepts (nice to have)
• Basic knowledge of relevant standards (e.g., NFPA 855, NFPA 68/69, IFC, international fire codes) (nice to have)
• Experience with other CFD tools (ANSYS Fluent, OpenFOAM, CFX)
• Experience with Python workflow automation (nice to have)
• Interest in research, model validation, and advanced simulation methodologies

What you'll experience working for ULS
UL Solutions has been pioneering change since 1894 and we're still leading the way. From day one, we've blazed a trail protecting the planet and everyone on it. Our teams have influenced billions of products, plus services, software offerings and more. We break things, burn things and blow things up. All in the name of safety science.
That's where you come in - because none of it could happen without you. It takes passion to protect people, problem-solving to safeguard personal data and conviction to make the world a more sustainable place. It takes bold ideas and brilliant minds to build a better world for future generations across the globe.
This is more than a job. It's a calling. A passion to use our expertise and play our part in creating a more secure, sustainable world today - and tomorrow. As a member of our safety science community, you'll use your ideas, your energy and your ambition to innovate, challenge and ultimately, help create a safer world.
Everyone here is unique. But we're also a global community, working together to help create a safer world. Join UL Solutions and you can connect with the brightest minds in the business, all bringing their distinct perspectives and diverse backgrounds together to deliver real change.
Empowering our customers to keep the world safe means thinking ahead. It means investing in training and empowering our people to learn and innovate. At UL Solutions, we help build a better future - one where everyone benefits.
Join UL Solutions to be at the center of safety. To learn more about us and the work we do, visit UL.com
Total Rewards: We understand compensation is an important factor as you consider the next step in your career. The estimated salary range for this position is $100,000 to $130,000 USD and is based on multiple factors, including job-related knowledge/skills, experience, geographical location, as well as other factors. This position is eligible for annual bonus compensation with a target payout of 10% of the base salary. This position also provides health benefits such as medical, dental and vision; wellness benefits such as mental and financial health; and retirement savings (401K) commensurate with the standard rewards offered in each individual location or country. We also provide full-time employees with paid time off including vacation (15 days), holiday and personal days (totaling 12 days) and sick time off (72 hours).
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About Us
A global leader in applied safety science, UL Solutions (NYSE: ULS) transforms safety, security and sustainability challenges into opportunities for customers in more than 110 countries. UL Solutions delivers testing, inspection and certification services, together with software products and advisory offerings, that support our customers' product innovation and business growth. The UL Mark serves as a recognized symbol of trust in our customers' products and reflects an unwavering commitment to advancing our safety mission. We help our customers innovate, launch new products and services, navigate global markets and complex supply chains, and grow sustainably and responsibly into the future. Our science is your advantage.