# gst: diffusivity of ordered and freely evolving bubbly suspensions.

AA << investigate the dispersion of a passive scalar such as the concentration of a chemical species, or temperature, in homogeneous bubbly suspensions, by determining an effective diffusivity tensor. Defining the longitudinal and transverse components of this tensor with respect to the direction of averaged bubble rise velocity in a zero mixture velocity frame of reference, (AA) focus on the convective contribution thereof, this being expected to be dominant in commonly encountered bubbly flows. >>

<< In the limits of low and of high Péclet number, including inertial effect of the flow does not affect the scaling of the effective diffusivity with respect to the Péclet number. These results are confirmed by direct numerical simulations performed in different flow regimes, for spherical or very deformed bubbles and from vanishingly small to moderate values of the Reynolds number. Scalar transport in arrays of freely rising bubbles is considered by us subsequently, using numerical simulations. In this case, the dispersion is found to be convectively enhanced at low Péclet number, like in ordered arrays. At high Péclet number, the Taylor dispersion scaling obtained for ordered configurations is replaced by the one characterizing a purely mechanical dispersion, like in random media, even if the level of disorder is very low. >>️

Aurore Loisy, Aurore Naso, Peter D. M. Spelt. The effective diffusivity of ordered and freely evolving bubbly suspensions. arXiv:2301.00028v1 [physics.flu-dyn]. Dec 30, 2022. 

https://arxiv.org/abs/2301.00028

Also

keyword "bubble" in FonT

https://flashontrack.blogspot.com/search?q=bubble

keyword "bolla" | "bolle" in Notes (quasistochastic-poetry): 

https://inkpi.blogspot.com/search?q=bolla

https://inkpi.blogspot.com/search?q=bolle

Keywords: gst, bubble, bubbly suspensions, diffusion, fluctuation

# behav: a viral marketing generated by low levels of advertising

<< What they discovered refutes Gladwell's (Malcolm Gladwell) concept that network position is always paramount. They found that in instances where there is even a small amount of advertising—even when it is just a quarter of a percent as strong as word-of-mouth—there's virtually no difference between the influence of the person at the center of a network and those further out on the string. >> 

 << It's not that word-of-mouth doesn't matter—it's that nobody is particularly important for the word-of-mouth process, (..) What we saw is that when advertising doesn't exist, when advertising is exactly zero, it looks like whoever is Mr. Popular, whoever has the most central connections, really matters. And in that scenario, if you start with that person at the center of the network, like the leader of an organization or company, rather than the intern, then whatever you're selling gets an uptick. >> Gabriel Rossman. 

Jessica Wolf. Forget what you think you know about viral marketing, study suggests. University of California, Los Angeles. Feb 25, 2021.

https://phys.org/news/2021-02-viral.html  

Gabriel Rossman,  Jacob C. Fisher. Network hubs cease to be influential in the presence of low levels of advertising. PNAS. 118 (7) e2013391118. doi: 10.1073/ pnas.2013391118. Feb 16, 2021. 

https://www.pnas.org/content/118/7/e2013391118

FonT

this could also occur in the generation of fake news ...

keyword "fake" in FonT

https://flashontrack.blogspot.com/search?q=fake