Laminar to turbulent transition of pulsatile non-Newtonian fluids

 

MSc graduation project of Yuvraj Birdja
Location: Lab. for Aero & Hydrodynamics
Supervisor: C. Poelma, R. Delfos

Project description:

Under normal conditions, blood flow is laminar. However, diseases like aortic stenosis might cause the blood flow to become turbulent. Turbulent blood flow is known to be a health risk. Therefore, it is interesting to know under which physiological conditions transition from laminar to turbulent occurs. Previous research has shown pulsatile blood flow is more stable compared to steady flow. Goal of this thesis project is to find a relation between frequency and the critical Reynolds number and to get a better understanding why transition occurs at higher Reynolds numbers than would be the case for steady flow. The blood flow is approximated by a pulsatile, sinusoidal inlet velocity with characteristic amplitude, frequency and positive mean flow. These parameters will be described by dimensionless effective Reynolds-  and Womersley numbers, where the effective viscosity will be determined for the model fluid, a Xanthan-gum solution in water, that can be described using the Carreau-fluid model. An experimental setup using a gear pump to obtain the desired pulsatile flow is built by a former MSc-student. Main part of this setup is a 5 m long, 40 mm inner diameter Perspex pipe. An orifice plate will be used as a trigger mechanism. Measurements will be done using 2D-Particle Image Velocimetry (PIV).

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