Shear Rate for Utter Dummies

Shear rate and viscosity

If we had to pick a college major whose graduates are responsible for some of the worst offenses against scientific literacy at content farms, it would be difficult choosing between communications / journalism and English. Only a few of these self-appointed "experts on everything" have the background to write about anything more complicated than a lever -- and eHow.com's Soren Bagley is definitely not one of them. The English Lit major proved our point with his uninformed answer for "How to Calculate Shear Rate,"¹ which Leaf Group has moved from eHow to Sciencing.com.

We won't claim to be experts on fluid dynamics, but we're pretty sure we have people on staff who are far more conversant with the topic than Bagley, a five-time DotD winner with a BA degree. Soren's research, such as it is, consisted merely of attempting to reword the first non-wikipedia entry he found with a Google search. That one just happens to be from Schlumberger's oilfield glossary, and we do have oilfield experts on staff. They're smart enough to know that Bagley's introduction, which begins with

"Shear rate is a measurement used to describe the movement of fluid through a channel. Specifically, it expresses the fluid's change in speed, known as its velocity gradient...." ...could best be described as "woefully insufficient." Soren neglected to mention that shear rate measures the cross-sectional change in velocity at a point in a channel, pipe annulus, etc.; perhaps because he didn't understand "science-y" words like cross-section and annulus.

Because of his unfamiliarity with the topic, Bagley merely rewords an example calculation from the Schlumberger glossary:

• "Determine the velocity of the fluid. This is the speed at which the fluid is flowing through the channel. The measurement should be taken in meters per second.
• Determine the height of the channel. This is the distance between the two interior sides of the channel's top and bottom plate."

"Top and bottom plate"? Ummm, no, Soren, besides making a complete mess of geometry, that's not what the definition you tried to use says: Schlumberger says.

"Shear rate is the rate of change of velocity at which one layer of fluid passes over an adjacent layer."

Bagley's half-baked copy-reword-paste job on the Schlumberger definition is proof positive that he knew nothing about the topic, yet got paid to pretend expertise – or at least enough knowledge to reword something written by an expert. He had neither, hence his repeat appearance on the podium as the Antisocial Network's Dumbass of the Day.

¹ Bagley's attempt to describe this calculation apparently tripped the bullshit detector at Leaf Group, so they assigned a rewrite specialist to clean it up. Wonder of wonders, this one sort of knew what he was talking about (but not quite...). You can still, however, see Soren's version using the Wayback Machine at archive.org. Its URL was   sciencing.com/calculate-shear-rate-6527048.html

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