Vehicle Engineering Principal Computational Fluid Dynamicist Remote

Lead aerodynamic analysis, CFD, aeroelasticity, and fluid-structure interaction for clean-sheet autonomous aircraft — from blank-sheet concepts through simulation, test, and flight.

Grex Defense builds autonomous systems for air dominance. The character of conflict is changing, with autonomy, mass, and software now deciding outcomes. The advantage goes to whoever can field new capability first, and Grex Defense exists to provide rapid capability solutions for hard defense problems.

Grex Defense is seeking a Principal Computational Fluid Dynamicist to lead the development of aerodynamic analysis, CFD, aeroelasticity, and fluid-structure interaction capabilities for clean-sheet autonomous aircraft.

This is a senior, hands-on technical leadership role in an early-stage environment. You will work directly with the engineering leadership team to take aircraft from blank-sheet concepts through preliminary and detailed design, simulation, test, and flight. You will be responsible for determining how aerodynamic problems should be solved — not simply running an established CFD process.

You will help establish the tools, workflows, computational infrastructure, verification and validation practices, and aerodynamic databases required to rapidly develop new aircraft. This includes determining where hand calculations and low-order methods are appropriate, where high-fidelity CFD or fully coupled multiphysics simulation is required, and how these methods should work together throughout the design process.

As an early member of the engineering organization, you will also help define make-versus-buy decisions, evaluate commercial and academic tools, select outside partners, identify and hire key technical talent, and mentor engineers as the team grows.

• 15+ years of professional experience in computational fluid dynamics, aerodynamics, or closely related disciplines, using both commercial and academic/research CFD codes.
• Expert knowledge of fluid mechanics, aircraft aerodynamics, numerical methods, and aerodynamic design.
• Expert knowledge spanning low-order through high-fidelity methods: analytical/empirical approaches, lifting-line, vortex-lattice, panel/potential-flow, Euler, RANS, and URANS.
• Demonstrated ability to move between hand calculations, low-order models, and high-fidelity CFD, selecting the appropriate fidelity for the engineering decision at hand.
• Extensive external-aerodynamics experience: complete aircraft configurations, control surfaces, propulsion integration, and aerodynamic interference.
• Extensive internal-aerodynamics experience: intakes, ducts, cooling flows, heat exchangers, pressure losses, and exhaust flows.
• Expert understanding of aircraft static stability, trim, control derivatives, and dynamic/rotary derivatives.
• Experience developing aerodynamic models for angular rates, maneuvering flight, prescribed motion, forced oscillation, or other unsteady vehicle behavior.
• Demonstrated experience developing multidimensional aerodynamic databases for flight dynamics, controls, performance, loads, or real-time simulation.
• Expert knowledge of modern CFD meshing: structured, unstructured, hybrid, boundary-layer, overset, Cartesian, and adaptive approaches.
• Strong grasp of CFD verification and validation: grid and time-step convergence, numerical uncertainty, turbulence-model sensitivity, and correlation with physical testing.
• Expert understanding of HPC and modern compute architectures: parallel CFD, CPU/GPU computing, solver scaling, and efficient large analysis campaigns.
• Expert knowledge of aeroelasticity and fluid-structure interaction and their application to aircraft design.
• Strong understanding of static and dynamic aeroelastic phenomena: load redistribution, divergence,…