Abstract <p>Adiabatic and isothermal wall boundary conditions with slip and temperature jump are implemented and applied using the HyCFS-R code for simulating near-continuum flows. Validation is performed on external and internal flow problems. The flow around a T2-97 hollow cylinder flare is chosen as the external flow, and shock wave propagation in a long tube and low Reynolds number nozzle flow as the internal flow. It is found that for flow around a hollow cylinder flare, the implementation of slip boundary conditions leads to better agreement with experimental data on the positions of the flow separation and reattachment points than no-slip conditions. In the calculation using slip boundary conditions, the shock wave is found to propagate along the long tube faster than in the calculation using no-slip boundary conditions. The calculated shock wave propagation velocities are in satisfactory agreement with the experimental data. In the case of nozzle gas flow, the use of slip boundary conditions leads to better agreement between the calculated and experimental surface temperature distributions.</p>