[Numerical simulation of a new nonlinear iteration tomography based on deflection spectra]

A new deflection tomography was suggested and verified with a simulated flow field. The deflection programs for projection and inverse-projection were produced based on optical principle of refraction and mathematical, physical significance of tomography. With the authors' home-made simple self-correlative algebraic reconstruction technique (SSART), the program system for the new deflection tomography was worked out and named Nonlinear Iteration Tomography Based on Deflection Spectra. A section of a complex flow field was simulated with Gauss function. The deflection spectra of a beam of parallel rays, as they passed through the field, were figured out according to the deflection program for projection, and the relative projections were acquired from the spectra. The section was reconstructed with the projections by SSART. The reconstructed result was compared with the model in order to test the deflection programs for validity. The reconstruction effect was scaled with mean-square error (MSE) and peak error (PE). As a result, with SSART, the deflection programs could be used to reconstruct the simulated field accurately. The MSE of reconstruction in this case was about 0.000 09 to 0.000 11 after 503 iterations, and PE was about 0.007 to 0.013. So, the program system, Nonlinear Iteration Tomography Based on Deflection Spectra, can accurately reconstruct complex flow fields based on deflection information.