Principal Machine Learning Engineer

ABOUT US PhysicsX is a deep-tech company with roots in numerical physics and Formula One, dedicated to accelerating hardware innovation at the speed of software. We are building an AI-driven simulation software stack for engineering and manufacturing across advanced industries. By enabling high-fidelity, multi-physics simulation through AI inference across the entire engineering lifecycle, PhysicsX unlocks new levels of optimization and automation in design, manufacturing, and operations — empowering engineers to push the boundaries of possibility. Our customers include leading innovators in Aerospace & Defense, Materials, Energy, Semiconductors, and Automotive. 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 internal and external stakeholders, 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 within bioprocess and chemical engineering environments. You are highly proficient in at least one of Star-CCM+, OpenFOAM, or Fluent, and experienced modelling the complex flow behaviour that arises in industrial bioprocess systems. 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 5–7 years of industry experience (post-MEng, MSc, or PhD) in a commercial 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 * Proficiency in CFD solvers across open-source OpenFOAM and commercial platforms as a plus (Star-CCM+, Fluent or equivalent), including custom solver and boundary condition development. * Develop multiphase flow models for gas-liquid, solid-liquid, VOF, Euler-Euler/Euler-Lagrange approaches) across a range of industrial and process engineering applications. * Model non-Newtonian and complex fluid rheology modelling, including high-viscosity, shear-thinning, or particle-laden flow regimes * Reactive and coupled-physics flow modelling — link CFD with reaction kinetics, heat transfer, or domain-specific process models (e.g. biokinetic, combustion, or electrochemical frameworks) * Own meshing generation and strategy for complex industrial geometries, including rotating machinery, internal flow passages, spargers, and free-surface interfaces * Build robust parametric CAD models (NX, CATIA, or equivalent) tightly coupled with simulation pipelines, enabling automated design optimisation and DoE studies * Multi-physics model development end-to-end: geometry clean-up, meshing, solver setup, post-processing, and experimental data integration for model validation * Scale-up/scale-down methodology — translate small-scale experimental data to full-scale CFD models and iterating model fidelity against physical measurements * HPC experience: job scheduling, MPI-based distributed computing, GPU acceleration, and performance tuning for large-mesh transient simulations on cloud (Flux) and on-premise resources * Surrogate modelling and ML-CFD coupling — build reduced-order or AI surrogate models from high-fidelity CFD data to support design space exploration and process optimisation * Data pipeline literacy — structuring and curate CFD output datasets for downstream AI/ML training, active learning, and Pareto optimisation workflows; applying data sampling techniques (LHS, quasi-random, adaptive) to efficiently cover design space * Experimental validation workflows — compare simulation predictions against physical test data, interpreting discrepancies, and systematically improving model fidelity * Customer-facing delivery — partner with clients to scope and address complex engineering challenges via CAE and AI solutions; communicating results clearly, recommending actionable next steps, and balancing accuracy with efficiency under commercial deadlines ENGINEERING AND WORKFLOW * 5–7 years post-graduate experience  * 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   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 Shoreditch office with work-from-home days, giving you the flexibility to work sustainably while staying connected in person.   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 UK employment and equality legislation. This information is confidential, used only in aggregate form, and will not influence the outcome of your application.

We are hiring a Principal Machine Learning Engineer to work on cutting-edge R&D and translating research into customer-centric solutions.    As innovators in speech technology, our mission is to Understand Every Voice—a vision that has propelled us to be world leaders of Voice AI. Fuelled by innovation, inclusivity, and a passion for making a global impact through world-leading Speech AI, we're looking for an experienced Principal Machine Learning Engineer to accelerate our efforts towards exceptional speech solutions.  Our Modelling Team trains diverse models, including large self-supervised ones, supporting Speechmatics towards being the most accurate speech recognition system globally. It also ensures their deployment into production, working with the latest developments in ML, but also with the best engineering practices for software engineering and model serving.  This is a hands-on, technical leadership role with high ownership.  You will develop and deploy advanced speech systems that power our products as well as co-define the technical vision for ML, drive innovation, and mentor engineering teams. Your work will span the entire codebase.     What You’ll Do: * Develop and deploy ML models, translating research into scalable, maintainable code and services  * Optimise ML models for speed, accuracy, and cost efficiency  * Evaluate and integrate cutting-edge approaches into our ML stack * Identify and solve complex ML problems across the organisation * Define and enforce best practices for code quality, model lifecycle management, etc. * Mentor engineers and foster a culture of technical excellence and innovation * Co-define the long-term technical vision  What We’re Looking For: * Deep understanding of the modern Machine Learning stack, for example: * Knowledge of contemporary transformer architectures (e.g., GQA, KV-caching) and best practices * Expertise in distributed training techniques * Familiarity with optimisation strategies for model inference (e.g., dynamic batching, flash attention, speculative decoding) * Proven track record of developing and deploying models at scale * Expertise in Python, ML frameworks (TensorFlow, PyTorch), and experience with cloud platforms * Strong familiarity with MLOps principles, CI/CD pipelines, and containerization (Docker, Kubernetes)   With preferred backgrounds covering some of the following: * Experience with speech-to-text or text-to-speech  * Contributions to open-source projects or published research in top-tier conferences We encourage you to apply even if you do not feel you match all of the requirements exactly. The list of requirements is intended to show the kinds of experience and qualities we’re looking for, but it is not exhaustive. If you are interested in the role, the team, and our mission, we would love to consider your application. We are always open to conversations and look forward to hearing from you. Who we are: Speechmatics is the leading expert in Speech Intelligence, and uses AI and Machine Learning to unlock business value in human speech worldwide. We work with an amazing mix of global companies, and our technology can integrate into our customers stack irrespective of their industry or use case – making it the go-to solution to harness useful information from speech. Joining us means working with some of the smartest minds around the world, focused on cutting-edge projects and deploying the latest techniques to disrupt the market. We believe in putting people first; we’ll do all we can to help you develop your skills and give you the tools you need to thrive. Our Focus Fridays give you an undisturbed day of focus, offset with Together Tuesdays when we have our team meetings, so you've always got the right balance. We have structured a hybrid approach that includes 2-3 designated office days each week. This arrangement ensures that while we embrace the advantages of remote work, we also maintain the vital connection and synergy that only in-person interactions can foster. This is only the beginning; we’re looking for amazing people like you to continue our journey… What we can offer you: No matter what stage of your career you’re at - from paid internships and first-job opportunities through to management and senior positions - we’ll support you with the training and development needed to reach your career aspirations with us. There really is no shortage of opportunities here for you to get involved and collaborate with those around you to deliver your best work. We offer incredibly flexible working, regular company lunches, and birthday celebrations. But that’s not all. We’ve spoken to our teams to find out what they want. From Private Medical, and Dental for you and your family, through to global working opportunities, a generous holiday allowance and pension/401K matching, we want to make sure our employees and their families are looked after. Every employee will receive a working from home allowance for tech or home office equipment (on top of your choice of laptop and accessories of course). Our approach to parental leave is designed to support employees globally. While this varies by geo, we have support in place for parents (including adoption assistance and reproductive health services) to ensure they have the time and financial resources needed to care for their growing families. At Speechmatics, our mission is simple: Understand Every Voice out there.  That's not just about our tech – it's the heart and soul of who we are. We welcome different experiences, viewpoints, and identities. For us, it’s not just the right thing to do; it’s our catalyst for sparking innovation and creativity. Our teams thrive in an environment that celebrates and supports everyone – no matter their gender, identity or expression, race, disability, age, sexual orientation, religion, belief, marital status, national origin, veteran status, pregnancy, or maternity status. But we don’t just open the door to diversity – we actively welcome it. Why? Because we believe every unique voice adds something special to our team, leading us to smarter solutions and a better workplace. So, come as you are and join our Speechling community. We’re building a place where every voice not only gets heard but is also respected and valued. For more information on us, please visit our website and follow Speechmatics on our social channels via Twitter, Facebook, LinkedIn, and YouTube. WE RELY ON LEGITIMATE INTEREST AS A LEGAL BASIS FOR PROCESSING PERSONAL INFORMATION UNDER THE GDPR FOR PURPOSES OF RECRUITMENT AND APPLICATIONS FOR EMPLOYMENT.  #LI-HYBRID