Senior Thermal Engineer

About the Company We are a renewable energy and ocean technology company committed to rapidly developing and deploying technologies that will ensure a sustainable future for Earth by unlocking the vast energy potential of its oceans. Our focus is on capturing civilizational levels of ultra-low-cost renewable energy for applications including computing and affordable renewable fuels delivered to shore. The company is a public benefit corporation headquartered in Portland, Oregon, and backed by leading venture capitalists, philanthropic investors, university endowments, and private investment offices. We operate as an idea meritocracy in which the best ideas change the company’s direction on a regular basis. Our staff have worked at organizations such as SpaceX, Blue Origin, Boeing, Tesla, Apple, Virgin Orbit, Astra, Google, Amazon, Microsoft, New Relic, Bridgewater, Raytheon, Disney Imagineering, and the US Army and Air Force, as well as research universities, startups, and small companies across a range of industries. About the Job We are looking for a Senior Thermal Engineer who will own the end-to-end thermal simulation workflow for low- and high-power electromechanical systems operating in harsh marine environments, with a strong emphasis on rapid design iteration, first-principles thinking, and high-fidelity CFD where it adds real value. You will work closely with mechanical engineers, payload architects, electrical engineers, applied physicists, and the prototype team to evaluate concepts, improve designs, define thermal requirements, debug issues, and help move hardware from early architecture through prototype and field validation. The ideal candidate is an expert in thermal CFD and modern simulation workflows, including GPU-accelerated solvers or other methods that enable fast turnaround without sacrificing engineering accuracy. Candidates should have strong interpersonal skills and be able to thrive in a creative, scrappy, and collaborative environment in which the best ideas change the company’s direction on a regular basis. You will own your designs cradle-to-grave, from first concept through fabrication and deployment at sea. If you are an excellent engineer, regardless of your background, we want you to apply. This is an on-site role based in our Portland office. Responsibilities • Own thermal simulation and analysis workflows for onboard payloads, electronics, cooling systems, pressure-contained assemblies, and related mechanical systems. • Build and execute fast, reliable thermal CFD workflows that support rapid design iteration in close collaboration with mechanical design, electrical engineering, payload architecture, and prototyping teams. • Translate component-level thermal inputs, power maps, packaging constraints, and environmental conditions into actionable system and subsystem thermal requirements. • Analyze unit- and payload-level thermal architectures to define required airflow, liquid flow rates, heat sink performance, cold plate requirements, thermal interface assumptions, allowable pressure drops, and related cooling design parameters. • Work with electrical and mechanical engineers to define cooling interfaces and design targets that can be directly incorporated into board layouts, enclosure designs, heat sinks, manifolds, ducts, cold plates, and other hardware. • Evaluate and select appropriate modeling approaches, ranging from hand calculations and reduced-order models to detailed CFD, depending on the design question and required fidelity. • Assess GPU-accelerated and high-performance simulation tools for thermal analysis, including commercial and open-source options such as Fluent, STAR-CCM+, HELYX/OpenFOAM-based workflows, and emerging solver technologies. • Own the full simulation lifecycle, including geometry preparation, CAD interaction, meshing, solver setup, execution, debugging, convergence assessment, post-processing, visualization, and communication of results. • Work directly with CAD and design teams, including NX-based workflows, to simplify, prepare, and modify geometry for simulation and rapid design exploration. • Develop thermal models for high-power compute and electronics payloads, including conduction, convection, liquid cooling, heat exchangers, cold plates, sealed enclosures, and thermal interfaces. • Analyze cooling architectures for systems operating in rugged, space-constrained, and environmentally exposed conditions. • Support the design of cooling systems that may use ambient environmental heat sinks, liquid loops, pressure boundaries, and mechanically integrated thermal paths. • Identify dominant thermal resistances, failure modes, uncertainty sources, and design sensitivities using first-principles reasoning. • Validate simulation results against prototype tests, lab measurements, field data, and experimental observations. • Develop post-processing and visualization methods that clearly communicate thermal margins, flow behavior, hot spots, pressure losses, uncertainty, and design tradeoffs. • Partner with prototype and test teams to define instrumentation plans, test conditions, acceptance criteria, and validation approaches. • Help build reusable simulation pipelines, templates, automation, and best practices for thermal analysis across payload and onboard system designs. • Apply engineering judgment to identify misleading, overfit, under-resolved, or physically inconsistent simulation results. • Contribute to optimization and design exploration workflows, including adjoint methods, parametric studies, surrogate models, and automated geometry or cooling-system optimization where appropriate. Required Qualifications • Strong background in thermal engineering, heat transfer, fluid mechanics, and numerical simulation. • Deep experience with thermal CFD for electronics, compute systems, aerospace, marine, automotive, or other high-power engineered systems. • Demonstrated ability to use CFD as an engineering tool rather than as a black box. • Experience translating component-level heat loads, thermal limits, and packaging constraints into system-level cooling requirements and hardware design targets. • Experience with the full CFD workflow: geometry preparation, meshing, boundary condition definition, solver setup, convergence/debugging, post-processing, and validation. • Hands-on experience with one or more major CFD tools such as STAR-CCM+, ANSYS Fluent, HELYX/OpenFOAM, or comparable high-performance solvers. • Experience evaluating model fidelity, mesh sensitivity, turbulence models, conjugate heat transfer, transient effects, boundary condition uncertainty, and numerical error. • Ability to move quickly between analytical calculations, reduced-order models, and detailed CFD depending on the problem. • Experience working closely with mechanical and electrical design teams and iterating directly on hardware concepts. • Comfortable working with CAD geometry and simulation-prep workflows; NX experience is strongly preferred. • Strong communication skills and ability to work with high-bandwidth technical teams across mechanical engineering, electrical engineering, physics, controls, prototyping, and systems architecture. • Ability to clearly explain assumptions, requirements, results, uncertainty, and design implications to both specialists and non-specialists. • Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, Applied Physics, or a related field; advanced degree preferred. Preferred Qualifications • Experience designing and analyzing systems inside sealed enclosures, pressure vessels, marine housings, aerospace hardware, or ruggedized environmental packaging. • Experience with GPU-accelerated CFD, high-performance computing, or modern solver acceleration methods. • Thermal design experience for high-power compute systems, GPU/CPU clusters, data center hardware, power electronics, or dense electronics payloads. • Experience with liquid cooling systems, cold plates, heat exchangers, pumps, manifolds, coolant loops, heat sinks, airflow management, and thermal interface materials. • Experience defining thermal design requirements for board-level electronics, integrated payload assemblies, enclosure-level systems, or pressure-contained hardware. • Experience with conjugate heat transfer involving solids, fluids, interfaces, and enclosure-level thermal paths. • Experience with rapid prototyping, hardware bring-up, test planning, and simulation-test correlation. • Experience with offshore, marine, subsea, aerospace, defense, or other harsh-environment systems. • Familiarity with adjoint optimization, automated design exploration, topology/shape optimization, surrogate modeling, or reduced-order modeling. • Scripting or automation experience in Python, shell, Java macros, OpenFOAM workflows, or solver-specific APIs. • Experience building reusable simulation pipelines and standardized modeling practices for engineering teams. The above qualifications are desired, not required. We encourage you to apply if you are a strong candidate with only some of the desired skills and experience listed. What Success Looks Like • Thermal design questions are answered quickly, accurately, and at the right level of fidelity. • Electrical, mechanical, and payload teams receive clear cooling requirements and design targets early enough to influence architecture, layout, and hardware choices. • Mechanical and payload teams can iterate faster because simulation workflows are tightly integrated with design decisions. • CFD results are trusted because they are validated, physically interpretable, and communicated clearly. • Thermal margins, risks, and design sensitivities are identified early enough to influence architecture and hardware choices. • Simulation workflows become increasingly automated, reusable, and robust across payload and onboard system programs. Working Style We are looking for someone who combines deep technical judgment with practical engineering speed. You should be comfortable working from first principles, challenging assumptions, spotting bad simulation results, and choosing the simplest model that can answer the question. You should also be able to go deep when the problem demands it, including detailed CFD, conjugate heat transfer, design optimization, and validation against real hardware. This role will work closely with applied physicists, mechanical engineers, electrical engineers, payload designers, and prototype teams, so clear communication and strong technical range are essential. Compensation and Benefits If hired for this full-time role, you will receive: • Cash compensation of $155,000–$200,000. • Equity in the company. We’re all owners and if we’re successful, this equity should be far and away the most valuable component of your compensation. • A benefits package that helps you take care of yourself and your family, including: • Flexible paid time off • Health insurance (the company pays 100% of gold-level PPO plan for full-time employees, their partners, and dependents) • Dental insurance (the company pays 100% for full-time employees, their partners, and dependents) • Vision insurance (the company pays 100% for full-time employees, their partners, and dependents) • Disability insurance (the company pays 100% for a policy to provide long-term financial support if you become disabled) • Ability to contribute to tax-advantaged accounts, including 401(k), health FSA, and dependent care FSA • Relocation assistance to facilitate your move to Portland (if needed). Location Our offices, lab, and shop are located in Portland, Oregon.