Next seminar on Friday!

Rym Mehri will present her PhD thesis seminar this coming Friday.  She will be giving a talk on “Investigation and Characterization of Red Blood Cells Aggregation: Experimental and Numerical Study”.   The talk abstract is below.  All are welcome!

Date: Friday March 4

Time: 2:30pm

Room: CBY B205



Red blood cells (RBC) are the most abundant cells in human blood, representing 40 to 45% of the blood volume (hematocrit). These cells have the particularity to deform and bridge together to form aggregates under very low shear rates. Due to their unique mechanical properties, RBCs represent the focus of numerous experimental and numerical studies, especially, at the microscopic level. In fact, the theory and mechanics behind aggregation are not yet completely understood. Understanding the conditions of aggregate formation could provide a better understanding of the mechanics behind this phenomenon and could help to determine aggregate behaviour related to clinical application such as diabetes and heart disease.

The purpose of this work is to provide a novel method to analyze, understand and mimic blood behaviour in the microcirculation. The main objective is to develop a methodology in order to quantify and characterize RBC aggregates and hence comprehend the non-Newtonian behaviour of blood at the microscale. For this purpose, suspensions of porcine blood and human blood are tested in vitro in a Polydimethylsiloxane (PDMS) microchannel to characterize the RBC aggregates. These microchannels are fabricated using standard photolithography methods. Experiments are performed using a micro Particle Image Velocimetry (μPIV) system for shear rate measurements coupled with a high speed camera for the flow visualization. Corresponding numerical simulations are conducted using a research Computational Fluid Dynamic (CFD) Solver, Nek5000, based on the spectral element method.


RBC aggregate sizes are quantified in controlled and measurable shear rates environments for 5, 10 and 15% hematocrit. Aggregate sizes are determined using image processing techniques. Velocity fields of the blood flow are measured experimentally and compared to numerical simulations using simple non-Newtonian models (Power law and Carreau models).

This work establishes for the first time a relationship between RBC aggregate sizes and corresponding shear rates as well as one between RBC aggregate sizes and apparent blood viscosity at body temperature. The results of the investigation can be used to help develop new numerical models for non-Newtonian blood flow.


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