One of the most popular non-Newtonian viscosity equations is Casson model: 4kty k + + where = viscosity; 7= shear stress; = shear rate; T = yield stress; k Casson model constant Error (measured - calculated)^2 = Objective: to find two constants that fit the data using Excel Solver and calculate WBV over shear rate. Red cell: Target to minimize (i.e., the sum of errors) Green cells: Two constants to be varied Show your curve fit (i.e., calculated Casson) as a line Shear rate (1/s) WBV (CP) - measured WBV (CP) - calculated 300 5.0 150 5.2 100 5.7 50 6.7 10 10.5 5 13.5 2 20.4 1 30.5 Sum of Error --> ty yield stress (CP)*s ?