293: Is CFD Overkill for Your Scale-Up? Why It Belongs in Every Biotech Scientist's Toolkit with Christian Witz - Part 1

You've perfected your process at the bench. Now comes the part that keeps CMC scientists up at night: will it still work at 2,000L? Right now, most teams find out the hard way, through failed runs, wasted batches, and months of delay to patients waiting on a therapy. Christian Witz believes there's a better way: use computational fluid dynamics to see how your cells will actually behave at full scale before you ever run the process, and stop treating scale-up as a guessing game.
On this episode of the Smart Biotech Scientist Podcast, David Brühlmann talks with Christian, founder of SimVantage, about why he treats CFD as a tool every process engineer should use directly, not something you outsource to a specialist. Christian's path into biotech ran through heat pump simulations and GPU-based particle flow modeling before he rebuilt a legacy Fortran bioreactor simulation program in modern C++ and CUDA, work that became the foundation of SimVantage.
Topics discussed:
• Christian’s path from simulating heat pumps and particle flows to pioneering GPU-based bioreactor simulations (03:54)
• The surprising lack of full equipment characterization in the biotech industry compared to fields like oil, gas, and iron & steel (06:40)
• The interdisciplinary challenges and steep learning curve when entering biotech from other industries (08:07)
• Why academic spinouts matter and the practical realities of founding a company based on university-developed software (09:44)
• Reasons behind CFD’s low adoption in bioprocessing—perceived complexity, need for specialists, and historical limitations in algorithms and computing power (11:58)
• How recent advances in GPU power, algorithms, and cloud computing remove barriers for routine use of CFD in process development (14:35)
• Strategies for characterizing and scaling processes across various reactor types, from shake flasks to manufacturing reactors (16:39)
• Practical considerations and limitations when setting up comprehensive CFD characterizations, including simulation parameter choices (19:49)
Smart insight: The degree of reactor characterization depends on a company’s needs. Startups might analyze a scale-up project once, while contract manufacturers—handling diverse products—benefit from comprehensive, reusable characterization across all reactors and operating conditions. Simulations are guided by physics (density, viscosity, surface tension) rather than biological specifics, allowing quick adaptation to new media or cell types.
If this conversation got you rethinking your scale-up strategy, here are a few past episodes that go deeper on the pieces Christian touched on:
• Episodes 91 - 92 : Mass Transfer Secrets: Mastering Bubbles and kLa from Bench to Large-Scale Production with Lars Puiman & Rik Volger
• Episodes 245 - 246: Why Your Shake Flask Culture Doesn't Scale: OTR, Shaking Diameter, and How to Fix It with Tibor Anderlei
• Episodes 173 - 174: Mastering Hybrid Model Digital Twins: From Lab Scale to Commercial Bioprocessing with Krist Gernaey
• Episode 243: Turn Tech Transfer from a Gamble into a Managed Process: The 6-Pillar Biologics Scale-Up Framework
Connect with Christian Witz:
Website: www.simvantage.com (simvantage.com)
Christian’s LinkedIn: linkedin.com/in/christian-witz-84aa9b162
Christian’s email: christian.witz@simvantage.com
Free 5-day email course, The CMC Failure Chain: the five recurring CMC mistakes that put your promising program at risk → Get it here (smartbiotechscientist.com/#cmc)
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