A Multiphase Compressible-Incompressible Particle Method for Water Slamming
- Abbas Khayyer (Kyoto University) | Hitoshi Gotoh (Kyoto University)
- Document ID
- International Society of Offshore and Polar Engineers
- International Journal of Offshore and Polar Engineering
- Publication Date
- March 2016
- Document Type
- Journal Paper
- 20 - 25
- 2016. The International Society of Offshore and Polar Engineers
- MPS method, Slamming, particle method, compressibility effect, multiphase flow
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- 60 since 2007
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The high-speed impacts between water and structures, often referred to as “slamming,” are of crucial importance in the design of coastal/offshore structures. Several theoretical studies have been devoted to the prediction of slam loads (e.g., von Kármán, 1929; Wagner, 1932). However, in most classical theoretical studies, the air phase and its cushioning effect have been ignored. Several experimental works, on the other hand, highlighted the importance of the air phase during the impact. In particular, a pioneering experimental study by Chuang (1966) demonstrated considerably reduced impact pressures compared with the Wagner theoretical solution. Hence, numerical predictions of slam loads should be conducted by robust multiphase numerical methods that can appropriately model the dynamics of air and its cushioning (compressibility) effect.
A number of interesting numerical works have been devoted to the simulation of wave slamming with consideration of air entrapment and its cushioning effect. In particular, Ma et al. (2014) developed an advanced finite volume method (FVM)-based compressible multiphase method for violent aerated wave impact problems. Lind et al. (2015) proposed a compressible–incompressible smoothed particle hydrodynamics (SPH)-based method for wave slamming by solving the air phase via an explicit weakly compressible SPH (WCSPH) method and calculating the fluid phase via a semi-implicit incompressible SPH (ISPH).
This paper presents a novel compressible–incompressible multiphase projection-based particle method for the prediction of wave slamming loads. The considered particle method is an extended version of an enhanced multiphase moving particle semi-implicit (MPS) method (Khayyer and Gotoh, 2013). The proposed method solves an integrated form of Poisson pressure equations (PPEs) for the liquid phase and the gas phase. To further enhance accuracy, a modified version of the previously developed ECS scheme (Khayyer and Gotoh, 2013) is devised through calculations of minimum and maximum theoretical base values for activation of the ECS scheme, thus imposing allowable ranges of density variations for the phases.Verifications are conducted by considering a set of liquid impact and slamming problems, including a 2D liquid impact (Braeunig et al., 2009) and impacts of rigid plates on flat water surfaces corresponding to the experiments by Lin and Shieh (1997) and Verhagen (1967).
|File Size||4 MB||Number of Pages||6|