Computational Modeling Simulation Multiphysics Jobs in California

Voyager is an innovative defense, national security and space technology company committed to advancing and delivering transformative, mission-critical solutions. We tackle the most complex challenges to unlock new frontiers for human progress, fortify national security, and protect critical assets to lead in the race for technological and operational superiority from ground to space.
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The future belongs to those who build it. At Voyager Technologies, we're building technologies that protect lives, expand frontiers and prepare us for what's next. And we're doing that with people who are wired to solve, build, adapt and lead. These roles are not for the faint of heart.
You'll help lay the foundation for humanity's future. Join a culture where innovation thrives, curiosity is rewarded, and impact is real. We're a company of doers, thinkers and builders, united by purpose and grounded in reality.
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Job Summary:
We are seeking an Accelerated Physics Simulation Engineer. In this role, you will develop fast, high-fidelity physics simulation capabilities that allow AI agents to evaluate and optimize hardware designs over millions of design iterations.
You will work at the intersection of numerical methods, GPU computing, and machine learning surrogates. You will help build differentiable and surrogate physics models that can be called directly by ACE agents, and you will validate them against high-fidelity solvers and real test data. This role is ideal for a computational scientist or engineer who loves PDEs, GPUs, and turning overnight runs into millisecond-scale kernels-and who uses AI tools as a force multiplier, not a curiosity.
You will be joining the Agentic Computational Engineering (ACE) team, a specialized group within our Advanced Technology Development organization. ACE is responsible for building Voyager's Generative Engine - the AI-native platform that compresses complex hardware development cycles from years to days. We design agentic AI systems that pair deeply with physics simulation, test data, and modern manufacturing so that Design for Manufacturing (DfM), Design for Assembly (DfA), and Design for Test (DfT) are built into the very first line of code and the very first sketch of a design.
Responsibilities:

• Design and implement fast physics solvers (e.g., CFD, thermal, structural, plasma) suitable for use inside agentic optimization loops.
• Develop surrogate models (e.g., physics-informed neural networks, neural operators, graph neural networks) that approximate high-fidelity simulations at orders-of-magnitude lower cost.
• Integrate accelerated solvers and surrogates into the ACE platform so AI agents can call them as tools during design and optimization.
• Work with the ACE Applications Lead (Mechanical/Propulsion) to identify key regimes and quantities of interest and to ensure that accelerated models remain physically credible.
• Create and curate training and validation datasets by coupling commercial or open-source solvers (e.g., Ansys, COMSOL, Star-CCM+, OpenFOAM) with automated parameter sweeps.
• Profile and optimize GPU kernels and numerical pipelines, targeting large speedups over baseline codes while preserving required accuracy.
• Develop test harnesses, benchmarks, and diagnostics that track accuracy, stability, and performance of accelerated models over time.
• Use LLMs to accelerate boilerplate coding, experiment scripting, and documentation so you can focus on core numerical and physical insights.
• Leverage the most advanced LLMs and tooling to assist with complex mathematics and numerical simulation generation.

Required Qualifications:

• PhD in Computational Physics, Mechanical or Aerospace Engineering, Applied Mathematics, Computer Science (with a focus on numerical methods), or a related field; or Master's degree + 3 years of highly relevant experience.
• 0-3 years of post-PhD industry, startup, or postdoctoral experience (or 3-6 years total experience working in computational science/engineering).
• Hands-on experience implementing numerical methods for PDEs (e.g., FEM, FVM, FDM, particle or mesh-free methods) in research or production environments.
• Experience with at least one major scientific computing or ML framework (e.g., JAX, PyTorch, TensorFlow) and one GPU or performance-oriented technology (e.g., CUDA, PhysicsNEMO, etc).
• Demonstrated experience speeding up simulations or building surrogate models for physics problems, with quantitative before/after results.
• Demonstrated "AI-first" workflow: you use LLMs to help generate, refactor, and test code so you can spend more time on modeling and physics.

Preferred Qualifications:

• Experience with CFD, structural mechanics, heat transfer, or plasma physics as applied to aerospace or propulsion systems.
• Experience with electrical, power, and electromagnetic simulations as applied to PCB or RF systems.
• Prior work on physics-informed neural networks (PINNs), neural operators (FNO, UNO, etc.), or other ML-based surrogates for physical systems.
• Experience coupling commercial or open-source solvers (e.g., Ansys, COMSOL, Star-CCM+, OpenFOAM) with custom automation or optimization code.
• Familiarity with differentiable programming and adjoint methods for design optimization.
• A track record of side projects, open-source contributions, or competition results that demonstrate deep enthusiasm for computational physics and performance engineering.

Voyager offers a comprehensive, total compensation package, which includes competitive salary, a discretionary annual bonus plan, paid time off (PTO), a comprehensive health benefit package, retirement savings, wellness program, and various other benefits. When you join our team, you're not just an employee; you become part of a dynamic community dedicated to innovation and excellence.
To conform to U.S. Government space technology export regulations, including the International Traffic in Arms Regulations (ITAR) you must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State.
Voyager is an Equal Opportunity Employer. Employment decisions are made without regard to race, color, religion, national or ethnic origin, sex, sexual orientation, gender identity or expression, age, disability, protected veteran status or other characteristics protected by law.
Minority/Female/Disabled/Veteran
The statements contained in this job description are intended to describe the general content and requirements for performance of this job. It is not intended to be an exhaustive list of all job duties, responsibilities, and requirements. This job description is not an employment agreement or contract. Management has the exclusive right to alter the scope of work within the framework of this job description at any time without prior notice.
California pay range
$165,000-$250,000 USD
Washington DC pay range
$165,000-$250,000 USD
Washington pay range
$165,000-$250,000 USD