CFD Engineer - Multiphase/DEM

About us Re-architecting Engineering for the Age of Intelligence PhysicsX is the physics AI company for industrials. The company’s mission is to accelerate hardware innovation by overhauling what industrial engineering and manufacturing look like today. PhysicsX is building a new simulation software stack to deliver deep physics AI enablement across the entire engineering lifecycle. The company partners with leading organisations in aerospace & defence, automotive, semiconductors, materials, and energy & renewables, supporting them on some of their most critical and complex challenges. PhysicsX is headquartered in the United Kingdom, with offices in London, New York, and Singapore and an expanding presence in the Bay Area. Who We’re Looking For You are a problem solver and builder, passionate about creating practical solutions that help customers make better engineering decisions. You can grasp and apply advanced engineering concepts across multiple industries, and you excel at working directly with customers, often on-site, to develop high-fidelity simulation models that feed into AI tools that are both useful and used. You bring deep expertise in fluid mechanics, heat transfer, and multiphase modelling, including particle-laden flows, fluidised beds, and coupled CFD-DEM. You are highly proficient in at least one of Star-CCM+, OpenFOAM, or Fluent, and experienced with DEM codes such as EDEM, LIGGGHTS, or Rocky. You are adept at automating these tools to create scalable optimisation workflows. Experience in parametric CAD modelling (NX or CATIA) and coding in Python (or the ability to pick up new programming languages quickly) is an advantage. With 3–5 years of industry experience (post-MEng, MSc, or PhD) in a commercial, non-research environment, you are ready to hit the ground running. You are confident setting up simulations independently, interpreting complex results with rigour, and making sound decisions grounded in solid engineering judgement. What you'll do • Independently build complex multi-physics models, from geometry clean-up and meshing through to simulation, post-processing, and integration of experimental data for validation, spanning single-phase, multiphase, and coupled CFD-DEM regimes. • Develop and validate DEM models of granular and particle-laden systems, including fluidised beds, pneumatic conveying, mills, aerosols, suspensions and coating processes, applying appropriate contact models, size distributions, and coupling strategies. • Build robust parametric CAD models coupled with simulation pipeline automation to execute advanced design optimisation and DoE studies across large parameter spaces. • Partner with customers to address complex engineering challenges through advanced simulation and AI solutions. Present results clearly, recommend actionable next steps, and balance accuracy with efficiency under real project deadlines. • Work at the intersection of CAE and data science to generate high-quality simulation datasets for training machine learning and deep learning surrogate models. Apply smart sampling strategies to capture the design space efficiently and reduce computational cost. • Leverage Flux (our cloud platform) and on-premise HPC resources to accelerate high-fidelity modelling, going beyond standard setup practices to achieve genuine performance gains at scale. • Continuously improve engineering best practices, adapting simulation model setups and outputs to support the development of deep learning surrogates and physics-informed ML models. • Combine project leadership with a commitment to mentoring junior colleagues, contributing to a culture of collaboration, rigour, and shared growth. • Travel globally (North America, Europe, Asia, Oceania) up to 2–3 weeks per quarter to work on-site with customers building solutions together. What we're looking for Core simulation skills • Multiphase CFD: VOF, Euler–Euler, Euler–Lagrange, or mixture models • DEM modelling: EDEM, Rocky, LIGGGHTS, or equivalent • Coupled CFD–DEM workflows for particle–fluid systems • Heat and mass transfer modelling • Reacting flows and phase-change processes (advantageous) • Proficiency in Star-CCM+, OpenFOAM, or Fluent Engineering and workflow • 3–5 years post-graduate experience in industry (not research) • MEng, MSc, or PhD in mechanical, chemical, or process engineering • Python scripting and simulation automation • DoE, surrogate modelling, and design space exploration • Parametric CAD modelling (NX or CATIA advantageous) • Strong written and verbal communication with technical and non-technical audiences Our delivery teams drive innovation to turn AI models into practical solutions - read our blog to learn more about how you’ll contribute to this exciting journey! https://www.physicsx.ai/newsroom/how-delivery-makes-physical-ai-work-in-the-real-world What we offer Build what actually matters Help shape an AI-native engineering company at a formative stage, tackling problems that genuinely matter for industry and society. This is work with real-world impact - and something you can be proud to stand behind. Learn alongside exceptional people Work with a high-caliber, collaborative team of engineers, scientists, and operators who care deeply about doing great work, and about helping each other get better. We come from diverse backgrounds, but we share a commitment to operating at the highest level and addressing some of the most complex challenges out there. If you’re ambitious, thoughtful, and driven by impact, you’ll feel at home. Influence over hierarchy We operate with a flat structure: good ideas win - wherever they come from. Questioning assumptions and challenging the status quo isn’t just welcomed, it’s expected. Sustainable pace, long-term ambition Building meaningful technology is a marathon, not a sprint. We believe in balancing focused, ambitious work with a life beyond it. Our hybrid model blends time together in our New York office with work-from-home days, giving you the flexibility to work sustainably while staying connected in person. And it doesn’t stop there … 🚀 Equity options - share meaningfully in the company you’re helping to build. 💰 5% contribution to 401(k) - build long-term security with a strong retirement plan. 🍽️ Free team lunch 1x/week - good food, great company, and space to connect. 🏥 Private health insurance – comprehensive cover for you, offering total peace of mind. 👶 Enhanced parental leave – 3 months full pay paternity and 6 months full pay maternity leave, to provide extra flexibility during the moments that matter most. ☀️ 20 days of Annual Leave (+ Public Holidays) - because taking time to rest matters. 📈 Personal development – dedicated support for learning, development, and leveling up over time. 💪 Gympass / Wellhub (subsidized) – for you and up to 3 family members, supporting both physical and mental wellbeing. 💳 Flexible Spending Account (FSA) – set aside pre-tax dollars for eligible healthcare expenses. 🔎 Watch this space, we’re continuing to build this as we grow… We value diversity and are committed to equal employment opportunity regardless of sex, race, religion, ethnicity, nationality, disability, age, sexual orientation or gender identity. We strongly encourage individuals from groups traditionally underrepresented in tech to apply. To help make a change, we sponsor bright women from disadvantaged backgrounds through their university degrees in science and mathematics. We collect diversity and inclusion data solely for the purpose of monitoring the effectiveness of our equal opportunities policies and ensuring compliance with employment and equality legislation. This information is confidential, used only in aggregate form, and will not influence the outcome of your application.