Three cases, including a two-dimensional, an axisymmetric, and a three-dimensional flowfield, were studied to demonstrate the effectiveness and reliability of a method proposed for validation of numerical solutions of complex flowfields. Images of these flowfields were first constructed from numerical solutions based on the principle of experimental flow visualization, and then compared directly with experimental interferograms. Because both experimental and numerical results are of identical physical representation, agreement between them can be evaluated effectively by examining characteristic flow structures of the flowfields as well as comparing differences in density. An efficient algorithm for three-dimensional density integration was also proposed to replace the conventional one that is computationally expensive. The study shows that reliable validation can be achieved in this way because it allows a direct comparison between numerical and experiment results without any loss of accuracy in either of them. The validation method is highly recommended for three-dimensional flowfields where quantification of images from experimental flow visualization is very difficult or impossible.