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Unformatted text preview: Fluid rate of strain is proportional to applied stress (N) Non-N fluid rate not constant, doesnt recover to original form once force is recovered Newtons Law of visc. Tau = mu * dv/dy = delta P*r / 2L dVx/dy = sheer rate, rate of strain, velocity gradient ex. Ethyl alcohol, benzene, hexane, H20 Power rule: tau = m (du/dy)^n pseudo: n <1 polymers dilatant: n>1 dispersions Bingham Plastic Newtonian Power Law (Dilatant) Power Law (Pseudoplastic) Velocity Gradient, du/dy Shear Stress, o Bingham Plastic: T= T0 + m (du/dy) T0 = mag of stress need to make fluid move For high flow, vessels make large D to put Re in laminar range Turbulent flow in arteries, plaques and lipids will stick to vessel walls Apparent viscosity : Blood is both Newtonian and NN also thixotropic!!...
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- Fall '08
- Biomedical Engineering