The Sanal flow choking (PMCID: PMC7267099) and the streamtube flow choking are new theoretical concepts applicable to both the continuum and non-continuum fluid flows. Once the streamlines compacted, the considerable pressure difference attains within the streamtube and the flow within the streamtube gets accelerated to the constricted section for satisfying the continuity condition set up the conservation law of nature, which leads to the Sanal flow choking and supersonic flow development at a critical-total-to-static pressure ratio (CPR) due to the convergent-divergent (CD) shape of the streamtube. As the pressure of the nanofluid/non-continuum-flows rises, average-mean-free-path diminishes and thus, the Knudsen number lowers heading to a zero-slip wall-boundary condition with compressible viscous (CV) flow regime. Sanal flow choking is a CV flow phenomenon creating a physical situation of the sonic-fluid-throat in a duct at a CPR. Herein, we presented a closed-form-analytical-model, which is capable to predict exactly the three-dimensional boundary-layer-displacement-thickness of nanoscale diabatic fluid flow (flow involves transfer of heat) systems at the zero-slip-length. The innovation of Sanal flow choking model is established herein through the entropy relation, as it satisfies all the conservation laws of nature. The exact value of the 3D boundary-layer-displacement-thickness in the sonic-fluid-throat region presented herein for each gas is a universal benchmark data for performing high-fidelity in vitro and in silico experiments for the lucrative design optimization of nanoscale systems. The physical insight of the Sanal flow choking and streamtube flow choking presented in this letter sheds light on finding solutions for numerous unresolved scientific problems.