Numerical investigation of viscous effects on the gap resonance between side-by-side barges. (15th November 2017)

• Record Type: Journal Article
• Authors: Feng, X.; Bai, W.; Chen, X.B.; Qian, L.; Ma, Z.H.
• Is Part Of: Ocean engineering. Volume 145(2017)
• Page Start: 44
• Page End: 58
• Publication Date: 2017-11-15
• Subjects: Computational fluid dynamics -- Side-by-side -- Gap resonance -- Viscous damping -- Wave tank; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2017.08.060
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: This paper presents a numerical study of the gap resonance between two side-by-side barges by using a multiphase Navier-Stokes equations model. In order to verify the multiphase flow model, it is firstly applied to simulate a two-dimensional gap resonance problem for two fixed boxes under various wave conditions. A comparison of the free surface elevations obtained on successively refined grids confirms the mesh convergence of numerical solutions. The calculated wave elevation response amplitude operators (RAOs) in the gap compare well with the experimental measurements. The multiphase flow model is further extended to calculate a three-dimensional gap resonance problem for two adjacent rectangular barges. The computed free surface RAOs in the gap also agree well with the experimental results. A close examination of the flow velocity and vorticity in the gap region at the piston resonant mode reveals that large amount of vortices are generated by the sharp corners of the two barges and shed downwards, which provide an effective mechanism to dissipate the flow kinematic energy and to reduce the wave elevation in the gap. On the contrary, rounded corners are not able to induce the same level amount of vortices to dampen the gap resonance. The effects of incident wave steepness on the viscous damping associated with the twin-barge system are highlighted. Highlights: A CFD model based on the open source OpenFOAM platform is adopted for gap resonant problems. CFD simulation generates much improved predictions than the potential flow model for 2D side-by-side boxes. Flow separation and vortex shedding mainly account for the discrepancy between potential flow prediction and model test. In 3D simulation of side-by-side barges with sharp bilge the gap elevation RAO is dependent on the incident wave height. Side-by-side barges with rounded bilge show low viscous damping for the gap resonance.