{"id":702291,"url":"https://alion.io/job/xcimer-computational-physicist-fluid-dynamics","title":"Computational Physicist - Fluid Dynamics","company":{"id":685639,"name":"Xcimer Energy","domain":"xcimer.energy","url":"https://alion.io/company/xcimer","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Lever","truth_index":{"grade":"A","score":95,"open_postings":22,"ghost_share":0,"stale_share":0,"repost_share":0,"time_to_fill_p50_days":133,"computed_at":"2026-10-05T05:45:15Z"}},"role":"Science & Research","role_family":"Science & Research","seniority":null,"employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Denver, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":160000,"max":200000,"currency":"USD","period":"year","gross":null,"usd_annual":200000},"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"C++","optional":false}],"status":"live","first_seen_at":"2026-08-31T22:55:16Z","employer_posted_date":"2026-08-31","last_verified_at":"2026-10-06T01:31:31Z","board_verified":true,"closed_at":null,"days_open":35,"trust":{"level":"ok","repost_count":0,"flags":[],"days_open":34},"description":"Xcimer Energy leverages decades of research on Inertial Fusion Energy (IFE) combined with groundbreaking new laser architecture. Our mission is to deploy fusion power plants to meet global decarbonization goals as fast as possible. Xcimer has assembled a team of leaders in tough tech, fusion science, and manufacturing with a track record of rapid execution. Supported by leading investors, Xcimer is uniquely positioned to deliver limitless, clean, fusion power to combat climate change. Join us in powering a better world with inertial fusion!\nThis is a full-time, onsite role based at our headquarters in Denver, CO.\nAs a Computational Physicist (Fluid Dynamics) at Xcimer, you will contribute to the theoretical and computational development of multi-material radiation hydrodynamics models that support inertial confinement fusion (ICF). This role focuses on numerical methods for computational fluid dynamics (CFD), with emphasis on high-fidelity modeling of complex multi-physics systems relevant to fusion energy.\nYou will work closely with senior scientists and software engineers to develop, analyze, verify, and validate numerical methods and simulation capabilities within Xcimer's radiation hydrodynamics codebase. This is a hands-on technical role that blends mathematical modeling, numerical analysis, and high-performance scientific computing.\nThe ideal candidate brings deep expertise in numerical methods for fluid dynamics, hands-on experience with invariant-domain preserving (IDP) methods, strong experience with finite element frameworks (particularly deal.II), and the ability to contribute meaningfully to code development, scientific publications, and collaborative research efforts.\nResponsibilities\nMulti-Material & Radiation Hydrodynamics Modeling\nImplement and improve multi-material modeling approaches (e.g., interface tracking/capturing, mixture models, or related techniques).\n\nSupport coupling of hydrodynamics with radiation transport and other relevant physics modules for various equation of state and opacity models.\n\nAssist in developing robust algorithms for extreme thermodynamic and flow regimes relevant to ICF.\n\nNumerical Methods & Theoretical Development\nDevelop and analyze certifiably robust, invariant-domain preserving (IDP) numerical methods for computational fluid dynamics with emphasis on multi-material flows.\n\nContribute to mathematical modeling for multi-material systems relevant to inertial confinement fusion.\n\nSupport development of radiation hydrodynamics formulations, discretizations, and stabilization strategies.\n\nInvestigate accuracy, stability, and convergence properties of numerical schemes.\n\nContribute to solving complex inverse and forward problems in high-energy-density physics.\n\nVerification, Validation & Scientific Rigor\nCollaborate with Xcimer's verification and validation function to validate multi-material numerics, contributing domain expertise on expected physical behavior.\n\nContribute multi-material test problems and physical judgment to the shared benchmark suite.\n\nHelp ensure multi-material results are reproducible and scientifically credible, in partnership with the team that owns V&V methodology.\n\nCommunication & Collaboration\nCollaborate closely with physicists, applied mathematicians, and software engineers.\n\nContribute to internal technical documentation and external scientific publications.\n\nPresent findings in technical meetings and contribute to peer-reviewed journal articles and conference papers.\n\nQualifications\n Education: Ph.D. in Mathematics (preferred), Applied Mathematics, Computational Physics, or a closely related field, with a focus on numerical methods for fluid dynamics.\nStrong background in numerical analysis for PDEs, particularly for fluid dynamics.\nHands-on experience with invariant-domain preserving (IDP) methods or comparable certifiably robust discretization frameworks for hyperbolic/compressible flow.\nExperience with finite element methods and hands-on development using deal.II (strongly preferred) or similar frameworks.\nExperience developing scientific software in C++.\nExperience working in high-performance computing environments (MPI-based parallelism and large-scale simulations).\nFamiliarity with multi-material modeling techniques in CFD.\nExperience with verification and validation of numerical methods.\nStrong written and verbal communication skills, with demonstrated ability to contribute to scientific publications.\nMust be a U.S. citizen or national, U.S. permanent resident (current Green Card holder), or lawfully admitted into the U.S. as a refugee or granted asylum.\nDesired\nBackground in radiation hydrodynamics, high-energy-density physics, or related multi-physics domains.\nExperience with mathematical modeling for multi-material compressible flows.\nExperience coupling hydrodynamics with radiation transport.\nExperience contributing to large, research-grade scientific codebases.\nDemonstrated ability to balance theoretical rigor with practical computational 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