{"id":3697106,"url":"https://alion.io/job/flexcompute-rarefied-flow-solver-developer","title":"Rarefied Flow Solver Developer","company":{"id":7971,"name":"Flexcompute","domain":"flexcompute.com","url":"https://alion.io/company/flexcompute-inc","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Workable","truth_index":{"grade":"A","score":95,"open_postings":16,"ghost_share":0,"stale_share":0.188,"repost_share":0,"time_to_fill_p50_days":null,"computed_at":"2026-11-05T05:54:30Z"}},"role":"Backend","role_family":"Backend","seniority":"junior","employment_type":null,"work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Watertown, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"C++","optional":false},{"name":"CUDA","optional":false},{"name":"Linux","optional":false},{"name":"MPI","optional":false},{"name":"OpenMP","optional":false},{"name":"Python","optional":false},{"name":"C","optional":true}],"status":"live","first_seen_at":"2026-11-03T18:22:10Z","employer_posted_date":"2026-11-03","last_verified_at":"2026-11-05T14:59:28Z","board_verified":true,"closed_at":null,"days_open":1,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":1},"description":"Flexcompute is a cutting-edge technology startup that specializes in ultra-fast simulation technology. Our products are utilized by companies in designing and optimizing technology products, with applications ranging from designing airplanes and cars to wind turbines and quantum computing chips. Our customer base includes both household names and startups in emerging industries. Our company was founded by world-renowned leaders in simulation technology from Stanford University and MIT. Backed by top VC firms, we are poised to disrupt the billion-dollar engineering simulation industry with our fast-growing trajectory.\nFlexcompute is seeking an experienced software developer to contribute to a rarefied gas simulation software and AI tool designed for GPUs. The successful candidate will have a critical role in designing and implementing cutting-edge algorithms with an emphasis on speed, robustness, accuracy, and scalability. This position offers a unique opportunity to explore state-of-the-art rarefied gas prediction and artificial intelligence algorithms in a production environment. The candidate will gain experience working with highly experienced professionals and be an integral part of the product development, release, maintenance, and support phases. Over time, the strong collaborative nature of this role offers exposure to Flexcompute’s sophisticated multi-physics simulation and design optimization technologies.\nWhat You Will Do:\nIndependently implement, test, and document new solver features\nProfile and optimize feature implementation to improve speed and scalability on CPUs/GPUs\nContribute to a clean and maintainable API for various functionalities\nContribute to general source code maintenance and other relevant software development activities (bug fixes, support, etc)\nCollaborate with teams developing agentic user interface and scientific visualization tools/technologies\nCollaborate with Product Management, QA, and Documentation teams to accomplish product milestones in a timely manner\nFollow sound software engineering practices. The code we write today will underpin our platform simulation products for years to come - it needs to be maintainable, extensible and robust\nMake user experience a priority. We strive to make the complexity inherent in fluid simulations manageable by way of intuitive controls and straightforward workflows\nDeliver robust and high-performance simulations for industrial applications that involve management of large amounts of data\nRequirements\nStrong background in Rarefied Gas Dynamics, Fluid Mechanics, Structural Mechanics, Aeroacoustics, Conjugate Heat Transfer, or adjacent fields\nKnowledge of numerical methods for solving rarefied flows such as Direct Simulation Monte Carlo (DSMC), Particle-in-Cell (PIC), or lower-fidelity engineering methods; knowledge of solving discretized Navier Stokes equations for compressible flows.\nBasics of computational geometry and meshing requirements for CFD simulations\nProven experience in and contributions to complex rarefied gas or CFD solvers\nC++ for scientific computing and Python (or similar) for scripting\nMaster degree or PhD in an applicable technical field with 0-3 years of industry experience\nFamiliar with version control systems such as git and the Linux command line\nPreferred:\nIndustry experience with implementation and testing of new features in commercial gas dynamics or CFD solvers\nPrior experience in working collaboratively in a medium sized distributed development team\nPhD in Computational Science and Engineering, Mechanical Engineering or Aerospace Engineering\nExpertise in one or more of the following topics:\nRarefied gas dynamics: kinetic theory and molecular gas dynamics, plume impingement (chemical and plasma plumes), plume-surface interactions, reacting plumes, lunar/Martian dust propagation, Hall effect thrusters, etc.\nDirect Simulation Monte Carlo (DSMC), Particle-in-Cell (PIC) techniques for modeling rarefied gases or plasmas\nAI surrogate models of fluid dynamics \nSurface and volumetric meshing for CFD\nDevelopment of scalable, parallel CFD solvers using CUDA, HIP, MPI, OpenMP.\nBenefits\n Competitive compensation with equity of a fast-growing startup.\n Medical, dental, and vision health insurance.\n 401(k) Contribution.\n Gym allowance.\n Friendly, thoughtful, and intelligent coworkers.\n Join Us\nAs our market and products grow, we are rapidly expanding and searching for partners who are eager to grow in a dynamic environment, possess an entrepreneurial spirit, and can scale our team. Flexcompute is dedicated to providing equal employment opportunities. We firmly believe that talent from diverse backgrounds can bring our company a rich and varied perspective. We warmly welcome candidates from all backgrounds to join us on this passionate and challenging journey, together facing the most compelling challenges in engineering computation.\nJoin Flexcompute, where your expertise in advanced computing will contribute to accelerating innovation in various fields for the next industrial renaissance.\nFlexcompute is dedicated to promoting diversity, equity, and inclusion in the workplace. We are an equal opportunity employer that recognizes the value of diverse perspectives in achieving our mission. 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