Intern, R&D Graduate Summer - Computational Thermal & Fluid Mechanics - Onsite

What Your Job Will Be Like

As a Summer 2027 Code Developer Intern, you will design, implement, optimize, and validate new and existing simulation modules within Sandia's Computational Simulation software suite (Sierra, SPARC, STK, CTH, Alegra, SMASH). On any given day, you may be called on to:

• Develop algorithms for CFD, thermal analysis, solid mechanics, structural dynamics, and shock-driven phenomena
• Implement finite-element, finite-volume, finite-difference, explicit-dynamics, ALE, and adaptive-mesh strategies
• Integrate and extend material-response models for high-strain-rate, shock-loading, and fire-structure interactions
• Collaborate with verification, validation, and uncertainty quantification experts on code verification, solution verification, benchmark validation, and uncertainty quantification
• Optimize code performance on multicore CPUs, GPUs, and leadership-class HPC systems using MPI, OpenMP, CUDA/HIP, and Kokkos
• Apply AI-assisted development using Claude Code and Codex for coding, testing, refactoring, and documentation, while adhering to rigorous software-quality standards
• Contribute to automated testing pipelines, continuous integration, code reviews, and developer documentation

Due to the nature of the work, the selected applicant must be able to work onsite.

Salary Range

At Sandia, we value the important work done by our interns and its contribution to National Security. Because of this, our interns earn competitive pay rates. Our pay structure is based on earned credit hours, classification, and degree level. Your pay rate will be determined during the hire process and included in your offer package. You can view the Intern Pay Rate chart here.

Qualifications We Require

You bring the confidence and skills to be eligible for the job by meeting these minimum requirements:

• Earned bachelor's degree
• Currently attending and enrolled full time in the spring term immediately preceding the internship (or scheduled to graduate in the spring) in an accredited science, engineering, or math graduate program
• Minimum cumulative GPA of 3.0/4.0
• Ability to work up to 40 hours per week during the summer
• Ability to secure and maintatin a U.S. security clearance which requires U.S. citizenship

Note: If you have not yet started your graduate program, please apply to an undergraduate intern position.

Qualifications We Desire

• Graduate enrollment in computer science, mechanical engineering, aerospace/civil/structural engineering, applied mathematics, computational science, or related field
• Strong software development skills
• Experience with numerical methods or modeling in CFD, thermal analysis, fire modeling, solid mechanics, structural dynamics, shock physics, or coupled multi-physics
• Knowledge of using AI-assisted coding (e.g. Claude Code, Codex) for software development workflows
• Strong written and verbal communication skills
• Hands-on development within large-scale, object-oriented scientific code frameworks
• Experience with HPC and performance portability (MPI, OpenMP, CUDA/HIP, Kokkos)
• Strong skills developing software in C++, C, Fortran, Python, Java, Ruby, and/or Julia
• Background in explicit dynamics, high-strain-rate mechanics, fluid-structure interaction, conjugate heat transfer, or fire-structure coupling
• Demonstrated verification & validation expertise (regression testing, method-of-manufactured solutions, benchmark comparisons, UQ)
• Familiarity with software-engineering best practices (version control, CI/CD, code review)
• Evidence of technical achievement via publications, conference presentations, open-source contributions, or research projects
• Ability to work effectively in an Agile multidisciplinary team of code developers
• Ability to obtain and maintain a DOE security clearance

Posting Duration

This posting will be open for application submissions for a minimum of three (3) calendar days, including the 'posting date'. Sandia reserves the right to extend the posting date at any time.

About Our Team

The Computational Simulation Group develops next-generation, performance-portable simulation software in areas such as computational fluid dynamics (CFD), thermal analysis, fire modeling, solid mechanics, structural dynamics, shock physics, and tightly coupled multi-physics. Our tools support national-security applications, from impact and reentry systems to advanced energy concepts, on leadership-class supercomputers and emerging architectures. We partner with DOE, DoW, and other sponsors to deliver validated, scalable analysis software capabilities.

About Sandia

Sandia National Laboratories is the nation’s premier science and engineering lab for national security and technology innovation, with teams of specialists focused on cutting-edge work in a broad array of areas. Some of the main reasons we love our jobs:

• Challenging work with amazing impact that contributes to security, peace, and freedom worldwide
• Extraordinary co-workers
• Some of the best tools, equipment, and research facilities in the world
• Career advancement and enrichment opportunities
• Flexible work arrangements for many positions include 9/80 (work 80 hours every two weeks, with every other Friday off) and 4/10 (work 4 ten-hour days each week) compressed workweeks, part-time work, and telecommuting (a mix of onsite work and working from home)
• Generous vacation, strong medical and other benefits, competitive 401k, learning opportunities, relocation assistance and amenities aimed at creating a solid work/life balance*

World-changing technologies. Life-changing careers. Learn more about Sandia at: http://www.sandia.gov

*These benefits vary by job classification.

Security Clearance

Sandia is required by DOE to conduct a pre-employment drug test and background review that includes checks of personal references, credit, law enforcement records, and employment/education verifications. Applicants for employment need to be able to obtain and maintain a DOE L-level security clearance, which requires U.S. citizenship. If you hold more than one citizenship (i.e., of the U.S. and another country), your ability to obtain a security clearance may be impacted.

Applicants offered employment with Sandia are subject to a federal background investigation to meet the requirements for access to classified information or matter if the duties of the position require a DOE security clearance. Substance abuse or illegal drug use, falsification of information, criminal activity, serious misconduct or other indicators of untrustworthiness can cause a clearance to be denied or terminated by the DOE, resulting in the inability to perform the duties assigned and subsequent termination of employment.

EEO

All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, or veteran status and any other protected class under state or federal law.

NNSA Requirements for MedPEDs

If you have a Medical Portable Electronic Device (MedPED), such as a pacemaker, defibrillator, drug-releasing pump, hearing aids, or diagnostic equipment and other equipment for measuring, monitoring, and recording body functions such as heartbeat and brain waves, if employed by Sandia National Laboratories you may be required to comply with NNSA security requirements for MedPEDs.

If you have a MedPED and you are selected for an on-site interview at Sandia National Laboratories, there may be additional steps necessary to ensure compliance with NNSA security requirements prior to the interview date.