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Wave-induced instability of seabed may cause damage to coastal and offshore structures. This issue has been investigated mostly for mildly sloping (< 5 °) seabed considering uncoupled or one-way coupled response of wave and seabed interaction. However, some of the marine structures are founded on seabed with steeper slopes. In this study, the wave-induced response and instability of sloping seabed are evaluated using a coupled finite element model. The interaction between fluid and porous seabed accounting for the effect of fluid motion on the seabed response, and conversely the effect of seabed response on the fluid motion (but not on the surface wave profile) is considered. The results indicate that the system response (fluid pressure, stresses, etc.) and the extent of instantaneously liquefied zone within the sloping seabed with significant steepness are lesser than those for horizontal seabed. Moreover, for typical sediment and wave characteristics, for the flat seabed, the response obtained from fully coupled analysis is not significantly different from those obtained by uncoupled analysis. For the sloping bed, such difference is slightly greater as compared to that for the flat bed. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we present a block format of left-looking AINV preconditioner for a nonsymmetric matrix. This preconditioner has block 1 × 1 or 2 × 2 pivot entries. It is introduced based on a block format of Gaussian Elimination process which has been studied in [14]. We have applied the multilevel nested dissection reordering as the preprocessing and have compared this block preconditioner by the plain left-looking AINV preconditioner. If we mix the multilevel nested dissection by the maximum weighted matching process, then the numerical experiments indicate that the number of 2 × 2 pivot entries in the block preconditioner will grow up. In this case, the block preconditioner makes GMRES method convergent in a smaller number of iterations. In the numerical section, we have also compared the ILUT and block left-looking AINV preconditioners. [ABSTRACT FROM AUTHOR]

A significant amount of Methane gas in soil deposits at Fraser River Delta (FRD), Canada, was identified as it adversely impacted the stability of the sloping seabed in the area under waves and tides. In this study, an integrated FEM model is utilized to investigate the instability of FRD front due to 1985 storm waves. Despite earlier studies that focused only on the role of residual pore pressure reached at late wave cycles in inducing the slide of FRD front (using empirical correlations), the transient response of sediments at early wave cycles is considered herein. The effect of coupled-flow-and-deformation processes within the sediments on the extent of the sliding plane is considered. For wave-seabed interaction modeling, Biot's poroelasticity and linear wave theory are employed to represent the fluid and seabed domains, respectively. The slide evaluation of the sloping seabed is conducted using Strength Reduction Technique with Mohr-Coulomb failure criterion. The results indicate that the storm waves cause a shallow slide within the slope, and the proximity of the unsaturated layer to mudline exacerbated the instability condition. Moreover, instantaneous liquefaction zones are found to emerge away from the slope; thus, they may not lead to an exacerbated sliding of the slope. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we have used a complete pivoting strategy to compute the left-looking version of preconditioner. This pivoting is based on the complete pivoting strategy of the version of Gaussian Elimination process. There is a parameter to control the pivoting process. To study the effect of on the quality of the left-looking version of preconditioner with complete pivoting strategy, we have used ten different values of this parameter. In the numerical experiments section, the quality of the left-looking version of preconditioner with complete pivoting strategy has been compared to the quality of the right-looking version of this preconditioner. [Copyright &y& Elsevier]

Abstract: Flash point of six flammable binary mixtures, acetic acid+Pentan-1-ol, Pentan-1-ol+n-hexanol, acetic acid+n-hexanol, acetic acid+cyclohexanon, Pentan-1-ol+cyclohexanon, n-hexanol+cyclohexanon and ternary mixture of acetic acid+n-hexanol+cyclohexanon were measured using the tag close cup apparatus by equilibrium test method. In this study attempt has been made to assess prediction models including Liaw model, Wickey model and Catoire model to calculate the flash point of these mixtures. UNIFAC model is employed in the mixture flash point predictions, in non ideal assumption. The results revealed that the Liaw et al. model can predict the flash point of studied mixtures with good accuracy. Also UNIFAC model when no experimental vapor–liquid equilibrium data are available is applicable for taking account non ideal assumptions in flash point calculations. [Copyright &y& Elsevier]