Similarity law of fluctuating pressure spectrum beneath hydraulic jump

Similarity law is the conversion rule between model and prototype, on which a lot of research works have been done, with no agreement reached referring to the similarity law of fluctuating pressure frequency spectrum. Experimental data of peak frequency and dominant frequency range of fluctuating pressure spectrum beneath hydraulic jump obtained from serial models of scales 1:1, 1:2 and 1:5 are compared. As a result, similarity law of fluctuating pressure spectrum in the strongly rolling area agrees with the gravity law. As peak frequency and dominant frequencies of fluctuating pressures in hydraulic jump, toe and tail are rather low, and the similarity is often misunderstood to be λ _f = 1. However, the normalized spectrums of fluctuating pressures show that the similarity nearly agrees with the gravity law. Supported by the National Natural Science Foundation of China (Grant Nos. 50725929, 50538060 & 50679052), and the Program for New Century Excellent Talents in University of the Ministry of Education