Thermal blooming in complicated pipe flow

Based on the computational fluid dynamics (CFD) software, an emluator for the optics and fluency coupling effects is established by means of the user defined function (UDF). Thermal blooming effects in a special tube with axial pipe flow are modeled. The simulated results indicate that the velocity distribution of the pipe flow is very asymmetric. However, the fluid density distribution is almost not changed without laser beam heating. As laser beam couples with the fluency, the fluid density distribution varies greatly. The heterogeneous fluid density distribution induces the optical path distinction of the double pearl eye form. This phenomenon is also observed in the previous experiments. (authors)