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Non-Newtonian flows are widely studied because they can often exhibit unusual, even unexpected effects. Our research into non-Newtonian turbulence concentrates on the computational simulation of dilute particle suspensions. Experimental evidence shows that adding very small amounts of certain materials (1-30 wt ppm) to a Newtonian solvent, can cause significantly large reductions in turbulent drag (an effect first reported by B. A. Toms in 1949). In some cases, by using a combination of additives, it is possible to reduce this drag by up to 95%, compared with the original Newtonian solvent. Apart from the obvious industrial implications, this effect is also very important from a fundamental point of view. Since this drag reduction only occurs when the flow is turbulent, if we learn more about how these additives interact with the turbulence, we may find out more about the structure of the turbulence itself. Although drag reduction by additives has been extensively studied, the physical mechanism by which the additives actually produce this reduction has so-far remained elusive. We simulate our particle suspension via direct numerical simulation (DNS) whereby an initial velocity field is evolved in accordance with the momentum conservation equation (MCE). As with the Newtonian DNS we then perform "measurements" on this velocity field as it evolves. It is hoped that by implementing different MCE's corresponding to different particle models, a greater understanding of turbulent drag reduction and turbulence may result. Group contacts: |             
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