Senior Modeling and Simulation Engineer

Commonwealth Fusion Systems; Milpitas (CA); On-site; USD 146,000 - 210,000; Full time

Benefits offered by this job

Competitive compensation with equity

13 Company-wide Holidays

Flexible vacation days

10 sick days

Generous parental leave policy

Health, dental, and vision insurance

401(k) with employer matching

Professional growth opportunities

Team-building activities

Job summary

Commonwealth Fusion Systems LLC in Milpitas, California, is seeking a Senior Modeling and Simulation Engineer to lead multi-physics simulations for next‑gen fusion hardware. You will model thermal, structural, fluid, and chemical interactions and guide design decisions.

The role requires 7+ years of R&D simulation experience, mastery of ANSYS or COMSOL, and the ability to validate virtual models with physical test data. Equity, strong benefits, and a fast-paced, mission-driven environment.

Qualifications

• Master’s or PhD in Mechanical/Aerospace Engineering or Physics with computational mechanics focus.
• 7+ years of experience in simulation and predictive analysis of complex R&D systems.
• Expert in ANSYS, COMSOL Multi-physics, or equivalent high-end FEA/CFD tools.
• Proven ability to run coupled simulations (fluid-structure, thermal-structural, chemical).
• Ability to validate virtual models with physical test metrics (strain, thermal imaging, flow sensors).

Responsibilities

• Execute advanced FEA and CFD for processing equipment.
• Build, run, and evaluate highly coupled simulations covering structural mechanics, high-temperature thermal management, fluid/gas flow dynamics, and chemical reaction kinetics.
• Implement engineering workflows for simulation data management, mesh convergence criteria, and rigorous verification and validation using physical test data.
• Provide analytical leadership during technical design reviews, verifying margins and distributions to guide design choices.
• Collaborate with Mechanical Designers, Electrical Engineers, Materials Scientists, and Chemical Specialists to translate insights into hardware modifications.
• Own and report on modeling milestones, timelines, and computational resources to stakeholders.

Skills

7+ years of experience in simulation &

Multi-physics modeling

Empirical correlation

Education

Master’s or PhD in Mechanical/Aerospace Engineering or Physics

Tools

ANSYS

COMSOL Multi-physics

Job description

About Commonwealth Fusion Systems:

Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy.

Combining decades of research, top talent, and new technologies, we’re designing and building commercially viable fusion power plants. And we're working with policymakers, suppliers, and many others to build the energy industry of the future.

We’re in the best position to make it happen. Since 2018, we’ve raised $4 billion of capital, making us the largest and leading fusion company in the world.

Now we’re looking for more thinkers, doers, builders, and makers to join us. People who’ll bring new perspectives, solve tough problems, and thrive as part of a team.

If that’s you and this role fits, we want to hear from you.

Join the power movement as a Senior Modeling and Simulation Engineer

We’re looking for a Senior Modeling and Simulation Engineer to join our design team to help build next-generation hardware. In this role, you will serve as a lead technical expert for advanced simulations, driving the predictive validation of complex hardware systems.

This role requires a high-level practitioner in multi-physics simulation who can comfortably model complex interactions across thermal, structural, fluid flow, and chemical regimes. If you enjoy solving deeply complex physics problems, applying rigorous modeling standards, and working in a collaborative, fast-paced environment to deliver first-of-a-kind hardware, this is your opportunity to make an impact.

What you'll do:

• Execute Simulation and Modeling: Execute advanced Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) for advanced processing equipment
• Run Multi-Physics Analysis: Build, run, and evaluate highly coupled simulations covering structural mechanics, high-temperature thermal management, fluid/gas flow dynamics, and chemical reaction kinetics
• Apply Engineering Best Practices: Implement engineering workflows for simulation data management, mesh convergence criteria, and rigorous verification and validation (V&V) protocols using physical test data
• Drive Design Reviews: Provide analytical leadership during technical design reviews, verifying structural margins, thermal stress distributions, and flow uniformity to guide design choices
• Collaborate & Interface: Partner closely with cross-functional teams, including Mechanical Designers, Electrical Engineers, Materials Scientists, and Chemical Specialists, to translate simulation insights into actionable hardware modifications
• Project Accountability: Own and report on modeling milestones, timelines, and computational resources to stakeholders, ensuring on-time and in-spec delivery
• Get Things Done: Act with speed to solve critical engineering bottlenecks, validating design optimization paths from concept through prototype deployment

What we’re looking for:

• Education: Master’s or PhD degree in Mechanical Engineering, Aerospace Engineering, Physics, or a related field with a heavy focus on computational mechanics and multi-physics modeling
• Experience: 7+ years of experience in simulation and predictive analysis of complex R&D systems
• Software Mastery: Advanced, hands‑on expert in ANSYS, COMSOL Multi-physics, or equivalent high-end FEA/CFD simulation platforms
• Multi-Disciplinary Analytical Expertise: Proven track record of successfully running coupled simulations (e.g., fluid-structure interaction, thermal-structural behavior, and chemical reaction modeling)
• Empirical Correlation: Ability to bridge the gap between virtual models and the shop floor by validating simulation results against physical test metrics like strain gauge data, thermal imaging, and flow sensors

Bonus points for:

• Standards Knowledge: Familiarity with applying industry codes to simulation-driven design validation
• Motion & Dynamics: Experience running transient dynamic simulations or modeling precision motion systems in extreme thermal environments

Must-have requirements:

• Ability to lift up to 25 lbs occasionally
• Perform activities such as stooping, climbing, standing, sitting for extended periods of time
• Willingness to travel or work required nights/weekends/on-call occasionally
• Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, high current, pressure systems, and cryogenics

$146,000 - $210,000 a year

Salary range for this full-time position + equity + benefits

Benefits include:

• Competitive compensation with equity
• 13 Company-wide Holidays
• Flexible vacation days
• 10 sick days
• Generous parental leave policy
• Health, dental, and vision insurance
• 401(k) with employer matching
• Professional growth opportunities
• Team-building activities

At CFS, we excel in fast-paced environments, driven by our values of integrity, execution, impact, and self-critique. As we grow, we’re eager to bring on mission-driven folks who offer diverse perspectives and fresh ways to tackle challenges.

We value diversity deeply and are proud to be an equal opportunity employer by choice. We consider all qualified applicants equally, regardless of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law.

This role requires compliance with U.S. laws concerning the export of controlled or protected technologies or information (collectively, “Export Control Laws