Culture broth with secreted macromolecules and culture broth of filamentous fungi showing disperse growth exhibit elevated viscosity, usually with shear‐thinning flow behavior. High viscosity, however, poses a serious challenge in the production and research of these compounds and organisms. It commonly causes insufficient mixing and oxygen transfer in large‐ and small‐scale bioreactors. Computational Fluid dynamics (CFD) has been proven to be a valuable tool for the computation of important bioprocess parameters. The published literature for small‐scale shaken bioreactors, especially shake flasks, however, almost exclusively focuses on water‐like viscosity. In this paper, a previously published CFD model for 250 mL shake flasks was used to simulate experiments at high viscosities of up to 100 mPa·s. Compared to experimental data, the CFD model accurately predicted the liquid distribution and computed the volumetric power input with a deviation of less than 7% and the kLa value within a factor of two, compared to the kLa correlation from Henzler and Schedel. Furthermore, a novel approach to compute the shear rate was tested. Lastly, new insights into the out‐of‐phase phenomenon were gained. The presented data confirms the usefulness of the already established critical phase numbers of 0.91 and 1.26, while underlying the fundamentally smooth transition from in‐phase to out‐of‐phase operating conditions.

中文翻译：

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通过高粘度下体积功率输入、kLa 值和剪切速率的 CFD 计算来探索 Shake Flask 中的异相现象


具有分泌大分子的培养液和显示分散生长的丝状真菌培养液表现出较高的粘度，通常具有剪切稀化流动行为。然而，高粘度对这些化合物和生物体的生产和研究构成了严峻的挑战。它通常会导致大型和小型生物反应器中的混合和氧转移不足。计算流体动力学 （CFD） 已被证明是计算重要生物过程参数的宝贵工具。然而，已发表的关于小型摇动生物反应器（尤其是摇瓶）的文献几乎完全集中在类似水的粘度上。在本文中，使用先前发表的 250 mL 摇瓶 CFD 模型来模拟高达 100 mPa·s 的高粘度实验。与实验数据相比，CFD 模型准确预测了液体分布，并计算出偏差小于 7% 的体积功率输入，与 Henzler 和 Schedel 的 kLa 相关性相比，kLa 值在两倍以内。此外，还测试了一种计算剪切速率的新方法。最后，对异相现象有了新的见解。所提供的数据证实了已经建立的 0.91 和 1.26 临界相位数的有用性，同时为从同相到异相操作条件的基本平滑过渡奠定了基础。