Microscopic flows of suspensions of the green non-motile Chlorella micro-alga at various volume fractions: Applications to intensified photobioreactors

Antoine Souliès (1) , Jeremy Pruvost (1, 2) , Cathy Castelain (3) , Teodor Burghelea (3)

1 GEPEA-BAM - Bioprocédés Appliqués aux Microalgues
2 EPUN - Ecole Polytechnique de l'Université de Nantes
3 LTN - Laboratoire de thermocinétique [Nantes]

An experimental study of flows of the green non-motile Chlorella micro-alga in a plane micro-channel is presented. Depending on the value of the cell volume fraction, three distinct flow regimes are observed. For low values of the cell volume fraction a Newtonian flow regime characterised by a Poiseuille like flow field, absence of wall slip and hydrodynamic reversibility of the flow states is observed. For intermediate values of the cell volume fraction, the flow profiles are consistent with a Poiseuille flow of a shear thinning fluid in the presence of slip at the channel's wall. For even larger cell volume fractions, a yield stress like behaviour manifested through the presence of a central solid plug is observed. Except for the Newtonian flow regime, a strong hydrodynamic irreversibility of the flow and wall slip are found. The calculation of the wall shear rate and wall stress based on the measured flow fields allows one to identify the mechanisms of wall slip observed in the shear thinning and yield stress regimes.

Mots clés: Yield stress; Wall slip; Rheological hysteresis; Intensified photobioreactor; Chlorella microalga; Microfluidics; Nonlinear flow resistance

Domaines: Génie des procédés

Antoine Souliès, Jeremy Pruvost, Cathy Castelain, Teodor Burghelea. Microscopic flows of suspensions of the green non-motile Chlorella micro-alga at various volume fractions: Applications to intensified photobioreactors. Journal of Non-Newtonian Fluid Mechanics, 2016, 231, pp.91 - 101. ⟨10.1016/j.jnnfm.2016.03.012⟩. ⟨hal-01527163⟩