Quote:
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Originally Posted by blue2000s
That's still technically a Newtonian fluid.
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Hi,
Sorry, but I don't agree.
The shear stress of a petroleum oil or other Newtonian fluid at a given temperature varies directly with shear rate (velocity). The ratio between shear stress and shear rate is constant; this ratio is termed viscosity. The higher the viscosity of a Newtonian fluid, the greater the shear stress as a function of rate of shear.
In a non-Newtonian fluid -- such as a grease or a
polymer-containing oil (e.g.,
multi-grade oil) -- shear stress is not proportional to the rate of shear. A non-Newtonian fluid may be said to have an
apparent viscosity, a viscosity that holds only for the shear rate (and
temperature) at which the viscosity is determined. The shear failure point in most oils is between 4,000 and 8,000 psi.
Source -
http://www.lemd.com/motorsport/previous.cfm?id=19
Newtonian fluid - a fluid with a constant viscosity at a given temperature regardless of the rate of shear. Single-grade oils are Newtonian fluids.
Multigrade oils are NON-Newtonian fluids because viscosity varies with shear rate.
Source -
http://www.oilanalysis.com/dictionary/default.asp?definitionsearch=xqxqxqxq222&alphasearch=N
Newtonian Flow - Occurs in a liquid system where the rate of shear is directly proportional to the shearing force, as with straight grade oils which do not contain a polymeric viscosity modifier. When rate of shear is not directly proportional to the shearing force,
flow is non-Newtonian, as it is with oils containing viscosity modifiers.
Source -
http://www.chevron.com/products/prodserv/ehl/techterms.htm
I rest my case...
Happy Motoring!... Jim'99