It is hard to say what the best approch is without knowing anything about your code, but assuming you have access to the data why not just use the standard save command? Something like
filename = sprintf('cfd_data_at_time_%g.dat',t);
save( filename, cfd_data_at_time_step )
where t is the simulation time, and cfd_data_at_time_step a variable containing you data to save. This will save it in binary format, you can add the "-ascii" flag to save it as a text file.