Direct numerical simulations and modeling of pseudoplastic fluid mixing driven by a perturbed six‐bent‐blade turbine

ABSTRACT The cavern effect strongly impacts mixing efficiency in pseudoplastic fluids stirred in tanks. Perturbed six‐bent‐blade turbine impellers suppress cavern formation effectively, yet existing models cannot predict cavern size and morphology consistently. To overcome this, we develop a high‐fidelity framework coupling the lattice Boltzmann method with the immersed boundary method, enabling direct numerical simulations of pseudoplastic fluid mixing driven by a rotating perturbed six‐bent‐blade turbine. By varying mass concentration and rotational speed, we identify three distinct flow regimes. Based on these results, we propose an elongated heart‐shaped cavern model that predicts cavern geometry and size across regimes and apparent Reynolds numbers. Incorporating impeller perturbation effects, we further introduce a six‐petal rose model that captures the periodicity of the phase‐averaged flow field, achieving unprecedented accuracy in reproducing cavern morphology. Together, these models provide physical insights and practical tools for optimizing pseudoplastic fluid mixing.