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Category: Experimentation and Testing
Question: What is a good device to use for obtaining viscosity data for a non-newtonian fluid?
Keywords: v1i5,viscosity,measurement,non-newtonian,non,newtonian,fluids,shear,thinning,thickening,food
Answer: Consider a rotational viscometer. It will measure the shear rate applied and the subsequent viscosity at the same time. You can also vary the temperature and time the stresses are applied for the truly "fun" non-newtonian fluids. According to Cole-Parmer (a manufacturer of these devices):"The rotational viscometer measures viscosity by determining the viscous resistance of the fluid. This measurement is obtained by immersing a spindle into the test fluid. The viscometer measures the additional torque required for the spindle to overcome viscous resistance and regain constant speed. This value is then converted to centipoise and displayed on the instrument's LCD readout."When testing a tomato sauce sample, the following results were observed:"A sample of tomato sauce was analyzed to determine the product's viscosity profile. The test was conducted at a temperature of 25??C. An up/down speed ramp was performed from 10 to 100 RPM, giving a viscosity range of from 3,800 to 632.5 cP, over shear rates from 3.4 to 34.0 reciprocal seconds. The test data obtained for tomato sauce shows that this product exhibits a marked shear thinning viscosity profile over the test conditions." Source: Cole-Parmer
Links: More on the Tomato Sauce Test