Viscosity and Non-Newtonian Flow

Viscosity and Non-Newtonian Flow

1. Definition: Viscosity, mu, is a fluid property that characterizes resistance to flow

   • Equation: mu = shear stress/rate of shear strain
     • Used for Absolute Viscosity
     • Also used for dynamic viscosity
   • Kinematic Viscosity, nu, combines the viscous and mass characteristics of a fluid.
     • Equation: nu = mu/rho = viscosity/density

2. Newtonian Fluids

   • Definition: Fluids were shear stress may not be directly proportional to the rate of strain
   • Types
     • Shear ThinningFluids
       • Examples
         • paints
           • • Figure 4: "How to Treat a Paint Stain on Carpet - First Choice Carpet Cleaning." First Choice Carpet Cleaning. Web. 29 Apr. 2014.
         • printer ink
       • As stain increases, the ratino of shear stress to shear strain decreases
     • Bingham Plastic
       • Acts like solid for low values of shear stress... Acts like liquid at high values of shear stress
       • Example
         • Toothpaste
           • • Figure 1: "Midlothian Dental Arts." Midlothian Dental Arts The Truth About Toothpaste Comments. N.p., n.d. Web. 29 Apr. 2014.

3. Temperature's Effect

   • When temperature increases, viscosity decreases
     • Theory? Kinetic Energy increases to help intermolecular forces

4. Industry Applications

   • Viscosity of oil determines ability to pump from reservior
   • Temperature effects viscosity the most, so must keep regulated to regulate viscostiy
   • Measure viscosity by march funnel or rotational viscometer
     • • Figure 3: "Marsh Funnel Viscometer." For Drilling Mud Viscosity. N.p., n.d. Web. 29 Apr. 2014.
     • • Figure 5: "Extremely Lightweight Bullet Proof Vests." Body Armor Covert RSS. N.p., n.d. Web. 29 Apr. 2014.

5. Non - NewtonianFluids

   • Does not flow continuously
   • Examples
     • Kevlar
       • • Figure 6: "Rotational Viscometers Determine Dynamic Viscosity." LabHomepage. Web. 29 Apr. 2014.
     • Silly Putty
       • • Figure 2: "How to Get Silly Putty Out of Carpet." Mom Fab Fun. N.p., n.d. Web. 29 Apr. 2014.

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