PARALLEL PLATES Shear stress T dInT R OR= 3+ 2πR3 dIny Shear rate RO iR= h Newtonian fluids 2T and 2Th 0R= R 7= πR2 CONCENTRIC CYLINDERS T 01= 2πRh 'For narrow gaps'” R where R,≈R 少≈ RO R2-R How to measure the Torque measure dx T=kdx k=torsion bar constant 士 Angular Velocity 88 PARALLEL PLATES Ω R h Shear rate h R R Ω γ& = Shear stress ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ = + π γ σ ln & ln 3 2 3 d d T R T R Newtonian fluids σ R = 2T πR3 and η = 2Th πR4 Ω Ω CONCENTRIC CYLINDERS σ1 = T 2πR1 2 h h R1 R2 2 1 1 R2 R1 R R R where − Ω ≈ ≈ γ& “For narrow gaps” T = k dx Angular Velocity =Ω dx k k = torsion bar constant How to measure the Torque measure dx