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Frictional heating in plane Couette flow. (English) Zbl 0886.76020
When a liquid whose viscosity decreases as its temperature increases is made to undergo a simple shearing flow, the wall speed, or the centreline temperature, is a double valued function of the wall stress. This is called the base solution curve and the turning point is called the nose of the curve. The question we address is this: is there a point of neutral stability on this curve? The answer turns out to depend on whether the wall speed or the wall stress is the control variable.
We introduce an eigenvalue problem which explains the shape of the base curve. It leads to a useful definition of the nose and to a rule which forecasts when a nose ought to arise. It then helps us to determine where the neutral points lie. The result is this: if the wall speed is the control variable, there are no points of neutral stability; if the wall stress is the control variable, the nose of the curve is a point of neutral stability.

76D05 Navier-Stokes equations for incompressible viscous fluids
76E99 Hydrodynamic stability
80A20 Heat and mass transfer, heat flow (MSC2010)
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