Abstract: Related studies about wall functions, which are approximate solutions to turbulent boundary layers, are surveyed to shed light on the development of a pragmatic simulation method for hypersonic turbulent boundary layers. This overview reveals the following understandings: 1) The consistency between wall functions and numerical solutions determines the mesh size of the wall-next cells. However, the consistency problem is not well solved by analytical wall functions, especially in separation and reattachment regions where the pressure gradient is strong. The sub-grid wall function, in contrast, theoretically solves this problem, which makes it to be a promising method when computational resources are abundant. 2) The effects of strong compressibility and significant heat transfer in hypersonic turbulent flows need to be adequately integrated into analytical wall functions. Finally, the development of a more universal wall function based on the data-driven methods and sub-grid wall functions is recommended.