  The fastest supercomputer in 2020, Fugaku, has not only achieved digital
transformation of epidemiology in allowing end-to-end, detailed quantitative
modeling of COVID-19 transmissions for the first time, but also transformed the
behavior of the entire Japanese public through its detailed analysis of
transmission risks in multitudes of societal situations entailing heavy risks.
A novel aerosol simulation methodology was synthesized out of a combination of
a new CFD methods meeting industrial demands, CUBE, which not only allowed the
simulations to scale massively with high resolution required for micrometer
virus-containing aerosol particles, but also extremely rapid time-to-solution
due to its ability to generate the digital twins representing multitudes of
societal situations in minutes not week, attaining true overall application
high performance; such simulations have been running for the past 1.5 years on
Fugaku, cumulatively consuming top supercomputer-class resources and the result
communicated by the media as well as becoming official public policies.
