Quantitative evaluation of the shear threshold on C. tinctorius L. cell growth is vital for bioreactor system design and optimization of scaled-up industrial cultivation. The present research focused on investigating the effects of shear force on C. tinctorius L cell growth by computational fluid dynamic (CFD) analysis in shaken flasks. The results revealed that specific cell growth rates were greatly inhibited as the shear force increased from 1.17 to 2.42 Pa. Recovery of viability and aggregation diameter to their normal levels could be implemented after a 4-day adaptation with large fluctuations in physiological state. With further correlation analysis on shear force and C. tinctorius L. growth rate, a threshold value was identified at an average and maximum shear stress of approximately 0.55 Pa (0.06 w/kg) and 4.00 Pa (0.93 w/kg) according to the influence on cell growth. Quantitative data on shear effects can facilitate the design of industrial processes and lead to more rational scale-up in industrial C. tinctorius L cultivation. (C) 2016 Elsevier B.V. All rights reserved.