Sr. Thermal System Simulation Engineer

Rivian • Tustin, CA

11h

About The Position

Rivian is on a mission to keep the world adventurous forever. This goes for the emissions-free Electric Adventure Vehicles we build, and the curious, courageous souls we seek to attract.
As a company, we constantly challenge what’s possible, never simply accepting what has always been done. We reframe old problems, seek new solutions and operate comfortably in areas that are unknown. Our backgrounds are diverse, but our team shares a love of the outdoors and a desire to protect it for future generations.

Role Summary

Propulsion thermal system modeling is a mission-critical function at Rivian, enabling the virtual validation of propulsion cooling and refrigerant systems before physical SOP. In this role, you will lead the development of high-fidelity 1D and 3D CFD models to represent complex thermal responses at the vehicle level.
You will be responsible for bridging the gap between component-level design and vehicle-level performance, specifically for the existing and future platforms. This involves pushing the boundaries of simulation, from two-phase refrigeration CFD to 0D/1D drive-cycle system integration, to ensure our vehicles achieve industry-leading efficiency, range, and thermal reliability.

Requirements

• Education: Graduate Degree (MS/PhD preferred) in Mechanical or Aerospace Engineering with a strong foundation in thermodynamics, fluid mechanics, and heat transfer.
• System Modeling Expertise: 5+ years of experience in vehicle-level thermal simulations. Mastery of GT-Suite is required; familiarity with Simulink/Simscape is a plus.
• CFD Proficiency: Advanced experience in single-phase and multiphase CFD (Star-CCM+ or ANSYS Fluent). Proven ability to optimize complex fluid systems through simulation.
• Domain Knowledge: Excellent understanding of EV powertrain cooling loops, refrigeration systems, thermal components, and associated control strategies.
• Problem Solving: A proven track record of independent root cause analysis and the ability to find and push component boundaries to their limits.
• Communication: Exceptional interpersonal skills; ability to delegate and encourage delivery from cross-functional teams and external suppliers.
• CAD Experience: Familiarity with CATIA or ANSA for geometry extraction and simulation prep.

Nice To Haves

• Hardware Background: Hands-on experience with Thermal Chamber, Climatic Wind Tunnel, or coolant/refrigerant bench testing is a plus.

Responsibilities

• Lead Powertrain Cooling System Modeling: Own the creation, correlation, and release of 1D thermal models (GT-Suite, Simulink) for powertrain cooling and heating loops, including pumps, valves, hoses, and heat exchangers etc.
• Advanced CFD development: Drive high-fidelity CFD development for components and system developments, specifically targeting two-phase flow in refrigeration systems (suction lines, accumulator, manifolds etc.) and multiphase simulations (oil pick-up etc.).
• Virtual Sign-off & DVP: Own the drive-cycle virtual validation for aggressive propulsion thermal management. Translate component design boundaries into system-level DVP plans and lead performance sign-off discussions.
• Hardware-Simulation Integration: Collaborate deeply with hardware design engineers and suppliers to audit component performance (pump maps, HX rejection, test boundaries) and integrate physical test data from thermal chambers or wind tunnels into simulation twins.
• Strategic Optimization: Perform trade-off analysis between conflicting engineering constraints (e.g., component energy consumption vs. cooling performance) to optimize next-generation thermal architectures.
• Supplier & Stakeholder Management: Communicate technical requirements and simulation results across organization boundaries, acting as the bridge between DRE, system engineers and attribute leads.
• Model Version Control: Architect and maintain a robust supplier-based component performance maps and simulation archive to enable high-speed requirement simulation for future programs.

Benefits

• Rivian provides robust medical/Rx, dental and vision insurance packages for full-time employees, their spouse or domestic partner, and children up to age 26. Coverage is effective on the first day of employment.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level