Abstract:An analytical solutiongiven by Y.H. Kuo in 1953 for the incompressible flow past a flatplate at moderate Reynolds numbers was a classical work ofboundary layer theory. Many researchers, based on experimentaldata given respectively by Janour and Schaaf and Sherman, made anassessment of Kuo's formula and carried out follow-up studies fordetermining the drag coefficient around a flat plate. Kineticanalyses in the present paper show that the experimental data ofSchaaf {\&} Sherman in low subsonic situations ($0.16 < M < 0.21)$is not suitable to serve as a standard to assess an incompressibletheory when the Reynolds number ($Re$) ranges from 1 to 10,because the corresponding Knudsen numbers under the experimentalconditions are about between 0.03 and 0.3, indicating significantrarefied gas effects, while other experimental data satisfying theincompressible assumption support Kuo's formula. When rarefied gaseffects are taken into account, the drag coefficient around a flatplate in low-speed or subsonic situations may be expressed as $C_D= C_{D,c} \times C_{D,FM} /(C_{D,c} + C_{D,FM} )$, where $C_{D,c}$and $C_{D,FM} $ are the theoretical solutions at continuum andfree molecular limits, respectively. Kuo's solution for thevelocity distribution past a flat plate is in qualitativeagreement with the numerical results given by the informationpreservation (IP) method based on kinetic theory, with somedifference occurring at the leading edge where rarefied gaseffects become significant. Compared with Blasius solution to thevelocity distribution, Kuo's correction becomes important when$Re< 100$.