Stereo reconstruction of the free surface of breaking bow waves in a towing tank for DTMB 5415 model

Abstract

This study utilizes a binocular reconstruction system in a towing tank to conduct stereoscopic measurements of the breaking free surface of the quasi-steady bow wave of the DTMB 5415 model. It presents a detailed description of the application of binocular stereo technology in towing tank experiments, specifically focusing on how to enhance image features of the water surface texture, mitigate the impact of towing carriage vibrations, and achieve high-resolution reconstruction of the breaking wave surface. Experimental data show excellent agreement with standard reference results obtained from point measurements using a wave height sensor. An uncertainty analysis method for the binocular system measurements is proposed, addressing the issue of quantitatively evaluating errors in breaking wave surface measurements. The results present contour plots of wave elevation, velocity, and energy fields for the bow wave under different Froude numbers. Comparison with classical bow wave phenomena confirms that the wave surface elevation fields in both the disturbed and breaking regions can be reconstructed using the binocular system. At high speeds, the strong nonlinearity and breaking of the bow wave cause the magnitude of the velocity vector in the breaking region to exceed the forward speed of the ship model. The energy attenuation patterns along the wave crest differ for bow waves with varying degrees of breaking. This study provides reliable measurement techniques and direct data references for research on bow wave breaking.