Universal benchmark data of the three-dimensional boundary layer blockage and average friction coefficient for in silico code verification
Authors: Sanal Kumar V. R. , Sankar Vigneshwaran , Chandrasekaran Nichith , Saravanan Vignesh , Sukumaran Ajith , Rajendran Vigneshwaran , Choudhary Shiv Kumar , Radhakrishnan Pradeep Kumar , Oommen Charlie , Panchal Dhruv , Rafic Sulthan Ariff Rahman Mohamed , Bharath Rajaghatta Sundararam , Raj Yash , Shrivastava Srajan 
Published: April 2022

The first law of thermodynamics reveals that all fluids are compressible, and the second law of thermodynamics entails all fluids to have positive viscosity. These established laws reaffirm the possibilities of the occurrence of Sanal flow choking in yocto to yotta scale systems and beyond [Kumar et al., “Discovery of nanoscale Sanal flow choking in cardiovascular system: Exact prediction of the 3D boundary-layer-blockage factor in nanotubes,” Sci. Rep. 11, 15429 (2021); “Sanal flow choking: A paradigm shift in computational fluid dynamics code verification and diagnosing detonation and hemorrhage in real-world fluid-flow systems,” Global Challenges 4, 2000012 (2020)]. The Sanal flow choking occurs in the real-world flows at a critical total-to-static pressure ratio [Kumar et al., “Abstract P422: Sanal flow choking leads to hemorrhagic stroke and other neurological disorders in earth and human spaceflight,” Circul. Res. 129(1), AP422 (2021)]. At the Sanal flow choking condition, the Rayleigh-flow-effect (thermal choking) and the Fanno-flow-effect (choking due to frictional effects) unite at a unique site of the sonic-fluid-throat. In this article, the two-dimensional (2D) and the three-dimensional (3D) boundary-layer-blockage factors and average friction coefficient are generated for different working fluids passing through a cylindrical port, at the Sanal flow choking condition, as universal benchmark data for a credible verification of in silico codes for both adiabatic and diabatic flows. The outlook, advancement, and significance of the analytical methodology, invoked for developing Sanal flow choking model using well-posed initial conditions, for generating the universal benchmark data for computational fluid dynamics code verification are critically reviewed herein. The closed-form analytical models presented herein for predicting the 2D and the 3D boundary-layer-blockage factors at the sonic-fluid-throat of adiabatic and diabatic flows and average friction coefficient in a circular duct at the Sanal flow choking condition are fabulously unaffected with any errors due to discretization and fully freed from empiricism for a credible decision making on various high fidelity numerical simulations. The Sanal flow choking model offers the luxury to the scientific community for solving numerous unresolved problems in boundary layer theory. It provides universal benchmark data for various applications irrespective of the laminar/turbulence flow features in wall-bounded compressible viscous flow systems. The 2D and 3D in silico simulation results are presented for demonstrating conclusively the possibilities of the occurrence of the Sanal flow choking and streamtube flow choking [Kumar et al., “The theoretical prediction of the boundary layer blockage and external flow choking at moving aircraft in ground effects,” Phys. Fluids 33(3), 036108 (2021).] in internal and external flows. The phenomenological manifestation of the flow choking phenomenon reported herein extends disruptive technologies at the cutting-edge to solve century-long unresolved scientific problems in physics of fluids with credibility.