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Voids or porosities have been one of the biggest headaches in composite fabricators and are still a challenging issue. In this study, void behavior in a low pressurized area of the laminate during cure is identified and analyzed. And, the influence of material’s cure rate difference on laminate inner quality is evaluated and verified through material evaluation and test article fabrication with subsequent non-destructive and destructive inspection. When there is a surface film on outer layer of the laminate, it is confirmed that surface film acts as barrier layer to prevent void evacuation and keep voids locked in laminate during cure. And, under the same fabrication condition and process variables, except for a layer of surface film, trapped void have been properly evacuated and test article exhibited good inner quality.

A computational simulation of magnetohydrodynamic laminar blood flow under pressure gradient through a curved bio-vessel, with circular cross-section is presented. Electrical conductivity and other properties of the biofluid (blood) are assumed to be invariant. A Newtonian viscous flow (Navier–Stokes magnetohydrodynamic) model is employed which is appropriate for large diameter blood vessels, as confirmed in a number of experimental studies. Rheological effects are therefore neglected as these are generally only significant in smaller diameter vessels. Employing a toroidal coordinate system, the steady-state, three-dimensional mass and momentum conservation equations are developed. With appropriate transformations, the transport model is non-dimensionalized and further simplified to a pair of axial and secondary flow momenta equations with the aid of a stream function. The resulting non-linear boundary value problem is solved with an efficient, spectral collocation algorithm, subject to physically appropriate boundary conditions. The influence of magnetic body force parameter, Dean number and vessel curvature on the flow characteristics is examined in detail. For high magnetic parameter and Dean number and low curvature, the axial flow is observed to be displaced toward the center of the vessel with corresponding low fluid particle vorticity strengths. Visualization is achieved with the MAPLE software. The simulations are relevant to cardiovascular biomagnetic flow control.

This paper reports the cross-shore variations of a pressure gradient observed on a fixed barred beach in a large-scale laboratory wave flume. The data sets include measurements of the free water surface elevation, the near-bottom velocity and the near bottom pressure and the pressure gradient for one irregular wave and three regular wave cases. The cross-shore variation of the pressure gradient showed that the maximum value of pressure gradient appeared in the area of wave breaking, and the pressure gradients were influenced by the fluctuation of water surface elevation. The exceedance probabilities of pressure gradient were analyzed using irregular wave case data. Comparison of the onshore and offshore directions of the exceedance probability showed that the onshore direction dominant in this experiment; its values were generally large over the bar. The distribution of the exceedance probability of pressure gradient could be evaluated by the Weibull distribution.

The wave-induced pressure gradient, ∂p/∂x, at the bottom is related to fluid acceleration and sediment movement in the surf zone. Following similar large-scale laboratory work by Suzuki et al. [2008a], this paper deals with the observations and analysis of bottom pressure gradients on a natural sandy beach. The cross-correlation coefficients between ∂p/∂x and the water surface elevation are high even in the surf zone, and the coefficients are higher than the coefficients between ∂p/∂x and the vertical velocity component or ∂p/∂x and du/dt. The observed nonlinear characteristics of ∂p/∂x are weaker than the laboratory experimental data but extreme values of ∂p/∂x are larger than the experiments. The distributions of exceedance probability of ∂p/∂x are evaluated using the two-parameter Weibull distribution. The modulus of the Weibull distribution is evaluated as a function of local significant wave height normalized by the offshore significant wave height. The exceedance probability distributions of ∂p/∂x show a broader distribution for the field data compared to the laboratory, but are, nevertheless, predicted reasonably well with the Weibull distribution.

This paper presents a discussion on the role of impulsive pressures induced by plunging breakers acting on gravel beaches. In previous works, this process has been hypothesized to play a major role in the observed sediment transport on these beaches. Thus, a diagnostic investigation is carried out here in order to elucidate, in more detail, the anatomy of the impulsive signature in the pressure signal. For this purpose, we employ an integrated approach, which comprises full scale laboratory measurements and their comparison against model results from a well-validated phase/depth resolving numerical model based on the Reynolds-Averaged Navier-Stokes (RANS) equations. Agreement between observations and model predictions allows us to investigate the contribution of each of the acceleration terms in the momentum balance under the wave-impact event by means of the numerical model. The discussion is presented in order to understand how impulsive pressures are generated under plunging waves and their role in sediment mobilisation. Consistent with prior studies, numerical results show that under plunging breakers the local acceleration (du/dt) alone cannot be used as a proxy for pressure gradients. In addition, the importance of the term wdu/dz of total acceleration is recognised for first time. Results from this study suggest that for different types of breaking a different characterisation of the pressure gradient may be sought.