Senior Aerothermal & CFD Engineer

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. Senior Aerothermal & CFD Engineer We are seeking a Senior Aerothermal & CFD Engineer to develop computational fluid dynamics (CFD) and aerothermal solutions for Castelion's long-range hypersonic strike vehicles. This role is critical to predicting aerodynamic loads, pressure distributions, and thermal environments that drive vehicle design. You will work hands-on with multidisciplinary engineering teams to analyze, model, and validate complex fluid dynamic and aerothermal phenomena from concept through flight test in a fast-paced, hardware-driven environment. Responsibilities • Perform computational fluid dynamics (CFD) analyses of hypersonic flight vehicles across a wide range of Mach numbers and flight conditions • Predict aerodynamic loads, pressure distributions, and surface heating environments for flight vehicle structures and thermal protection system • Analyze shock interactions, boundary layer behavior, flow separation, and high-temperature flow phenomena • Develop high-fidelity CFD models to support propulsion integration, control surface design, thermal protection systems, and vehicle configuration trades • Work closely with flight sciences, TPS, structures, propulsion, GNC, and manufacturing teams to ensure seamless integration of aerodynamic and thermal analyses • Correlate CFD predictions with wind tunnel, arc-jet, ground test, and flight test data to improve model fidelity • Develop efficient meshing strategies, solver methodologies, and automated CFD workflows • Support design reviews by providing aerodynamic and aerothermal analyses that inform key technical decisions • Mentor junior engineers and contribute to best practices in CFD and aerothermal analysis • Partner closely with program leadership to make technical trades aligned with mission success Basic Qualifications • Bachelor's, Master's, or PhD in Aerospace Engineering, Mechanical Engineering, or related field • 5+ years of experience performing CFD and aerothermal analysis for aerospace or defense applications • Strong background in compressible fluid dynamics, hypersonic aerodynamics, and heat transfer • Experience using CFD tools such as STAR-CCM+, Fluent, FUN3D, CFD++, US3D, or equivalent • Experience with turbulence modeling, shock-boundary layer interactions, and high-temperature flow physics • Familiarity with aerothermal heating prediction and thermal protection system design support • Experience generating aerodynamic load and heating environments for structural and thermal analyses • Experience with scripting and automation using Python, MATLAB, or equivalent • Familiarity with wind tunnel testing, arc-jet testing, or flight test correlation • Strong problem-solving mindset, thriving in a fast-paced, hardware-rich, high flight cadence environment Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. Additional Eligibility Requirements This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.