The current research on 3-D disturbance flow analysis of particulate-induced transition is a follow-up study of prior work considering flow decomposition in 2-D only. In prior work , the 2-D disturbance flow field induced by a single particulate was analyzed for a M=5.35 boundary-layer flow by employing a biorthogonal eigenfunction system (BES). The disturbance flow field generated by particulate impingement is simulated utilizing an adaptive mesh refinement wavepacket tracking technique. The disturbance flow field is first analyzed in the frequency-wavenumber space employing fast Fourier transform to understand the spectral characteristics of different disturbance flow quantities. Next, the 2-D BES framework is extended to 3-D by considering non-zero spanwise wavenumbers. This approach allows the assessment of the contributions from the discrete and continuous modes to the disturbance flow field in 3-D which provides insight into the receptivity mechanisms for the particulate impingement.