Experimental investigation of a mechanically generated regular surface wave over turbulent current is carried out to understand the role of surface wave in combined flow. The recorded data sets enable obtaining reliable statistical parameters characterizing wavefield with depth. Variation in velocity power spectra along the flow depth in the mixed flow case is discussed. As seen from the velocity power spectra, the mechanically generated wave over turbulent current changes the spectral shape significantly. The dominant peak is observed in the power spectra at the wave-maker forcing frequency. The inter-relation between current only and the resulting flow field is examined by auto- and cross-correlation techniques. Also, the coherence of the resulting flow field is determined as a function of frequency using a cross-spectral of records. Additional problem considered in this study is closely related to the decomposition of the resulting recorded signal using the Hilbert-Huang transform (HHT) to determine the frequency of occurrence of the maximum energy carrying by the movement of a superimposed wave on turbulent current.
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