As the name suggests, this type of flow behavior is not affected by the length of time that the fluid has been flowing or being moved. We say it is unaffected by the duration of the shear which it experiences. This type of flow is the best documented, and some simple models of predicting flow exist to which we will later refer.
In this group we have Newtonian flow with which we are familiar, shear-thinning, shear-thickening, and viscoplastic flow. Please note once again that these non-Newtonian types of flow may be exhibited by fluids that will indeed also behave as Newtonian liquids over a
particular range of shear rates.
Shear-thinning liquids in general become more fluid, less viscous, as the shear rate on them increases. Typical examples of such fluids are: shower gel, hair conditioner, fabric conditioner, liquid abrasive cleaner, fabric washing liquid, printing ink, facial wash, flocculated clay slurries, 1 percent aqueous solutions of food thickeners (such as guar gum, locust bean gum, carrageenan, xanthan gum, alginate), most paints, many 1 to 2 percent aqueous polymer solutions, and some hydrocarbon crude oils.
In particular, with fluids such as flocculated clay slurries, which may have very high apparent viscosity at low shear rates, the fact that they are shear thinning enables us to pump them and convey them relatively easily by pipeline because of the high rates of shear applied by the fast spinning impeller of a centrifugal pump and the shear that they experience at the pipe wall (and another phenomena known as
wall slip that also reduces the viscosity at the pipe wall). Shear-thickening liquids are liquids whose apparent viscosity increases with increased shear rate. The old name for this is "dilatant" because the fluid appears to swell as it is sheared. The best way I can describe this is to ask you to think of a bucket of sand and water with about an inch of water above the settled sand. (Think back to your childhood visits to the seaside or sand pit.) Suppose you now rock the bucket from side to side; the sand and water mix together to form a rather unstable suspension. However, if you take a stick and try to stir the contents of the bucket with any appreciable amount of force it is virtually impossible. The suspension actually begins to look like a fractured solid. This is an extreme example of shear thickening. The voidage between the sand particles and the amount of water present
when the mixture behaves like a suspension is just enough to allow the mixture to flow at very low shear rates and let the particles move past each other. At high shear rates, the mixture expands, there is not.
THIXOTROPIC VISCOPLASTIC BINGHAM PLASTIC RHEOPECTIC
In this group we have Newtonian flow with which we are familiar, shear-thinning, shear-thickening, and viscoplastic flow. Please note once again that these non-Newtonian types of flow may be exhibited by fluids that will indeed also behave as Newtonian liquids over a
particular range of shear rates.
Shear-thinning liquids in general become more fluid, less viscous, as the shear rate on them increases. Typical examples of such fluids are: shower gel, hair conditioner, fabric conditioner, liquid abrasive cleaner, fabric washing liquid, printing ink, facial wash, flocculated clay slurries, 1 percent aqueous solutions of food thickeners (such as guar gum, locust bean gum, carrageenan, xanthan gum, alginate), most paints, many 1 to 2 percent aqueous polymer solutions, and some hydrocarbon crude oils.
In particular, with fluids such as flocculated clay slurries, which may have very high apparent viscosity at low shear rates, the fact that they are shear thinning enables us to pump them and convey them relatively easily by pipeline because of the high rates of shear applied by the fast spinning impeller of a centrifugal pump and the shear that they experience at the pipe wall (and another phenomena known as
wall slip that also reduces the viscosity at the pipe wall). Shear-thickening liquids are liquids whose apparent viscosity increases with increased shear rate. The old name for this is "dilatant" because the fluid appears to swell as it is sheared. The best way I can describe this is to ask you to think of a bucket of sand and water with about an inch of water above the settled sand. (Think back to your childhood visits to the seaside or sand pit.) Suppose you now rock the bucket from side to side; the sand and water mix together to form a rather unstable suspension. However, if you take a stick and try to stir the contents of the bucket with any appreciable amount of force it is virtually impossible. The suspension actually begins to look like a fractured solid. This is an extreme example of shear thickening. The voidage between the sand particles and the amount of water present
when the mixture behaves like a suspension is just enough to allow the mixture to flow at very low shear rates and let the particles move past each other. At high shear rates, the mixture expands, there is not.
THIXOTROPIC VISCOPLASTIC BINGHAM PLASTIC RHEOPECTIC
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