Hi Gianmarco, As per your suggestion, I went through the CompressibleBL.cpp as well as the FalknerSkanBL.cpp routines in order to initialize my case with a specific boundary layer solution. But, I am not clear how to implement it on the Nektar case file. Do I need to compile the BL code (CompressibleBL.cpp/FalknerSkanBL.cpp) separately and insert the output into the .xml file or is there a way to directly define the BL generator as a function of the initial condition section of the .xml file? I couldn't find any example using similar sort of case. Please suggest. Thanking you. Regards, Dev