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This paper incorporates the Bingham rheology model with the Navier&ndash, Stokes solver to simulate the tsunamis excited by a slump-type landslide. The slump is modeled as the Bingham material, in which the rheological properties changing from the un-yield phase to yield phase is taken into account. The volume of fluid method is used to track the interfaces between three materials: air, water, and slump. The developed model is validated by the laboratory data of the benchmark landslide tsunami problem. A series of rheological properties analyses is performed to identify the parameter sensitivity to the tsunami generation. The results show that the yield stress plays a more important role than the yield viscosity in terms of the slump kinematics and tsunami generation. Moreover, the scale effect is investigated under the criterion of Froude number similarity and Bingham number similarity. With the same Froude number and Bingham number, the result from the laboratory scale can be applied to the field scale. If the slump material collected in the field is used in the laboratory experiments, only the result of the maximum wave height can be used, and significant errors in slump shape and moving speed are expected.

During operation, exhaust manifolds must bear the corrosion of high temperatures and repeated stress, which can easily lead to cavitation, corrosion, and creeping damage in the casting structure and affect product safety. To improve the structure of exhaust manifolds and increase their service life, we employed AnyCasting mold flow analysis to SUS304 stainless steel exhaust manifolds. We examined the influence of casting system design and process parameters such as ceramic shell temperature, casting temperature, and pouring speed on the filling and solidification processes of the liquid metal. Finally, we used the Niyama criterion to predict the probability and distribution of shrinkage porosity defects in the exhaust manifold and made improvements to enhance the quality of exhaust manifold castings. Keywords: exhaust manifold, mold flow analysis, casting system.

The shedding and evolution of the vortical structures generated by a solitary wave propagating over a submerged cylindrical structure are investigated experimentally and numerically. The cylindrical structure consists of two concentric cylinders and represents a simplified model for an offshore submerged intake structure typically used in coastal power plants. Flow visualization by dye injection is used to identify the dominant vortical structures near the structure. The flow visualization results show an unexpected flow reversal that causes shedding of secondary vortical structures. The experimental results are used to check a three-dimensional volume of fluid-large eddy simulation (VOF-LES) numerical model. The VOF-LES model is then used to further study the flow structure. A total of six dominant vortical structures generated by the wave motion are identified, followed by two more generated by the flow reversal. In summary, this paper provides the vorticity evolution for a complex fluid–structure interaction problem and a three-dimensional numerical simulation tool has also been validated, which can be extended to study more complex geometries and wave conditions.

This study uses a three-dimensional, compressible, turbulence model to investigate the pressure waves generated by two trains passing each other in a tunnel. The turbulent flow around the train bodies is computed by the RNG k–ɛ turbulence model; a sliding mesh method is utilized to treat the moving boundary problem. The numerical results are verified through the results of laboratory experiment and field observation. Then, a series of numerical simulations are carried out to examine the influences of the tunnel length, the blockage ratio, the train speed and the intersecting location on the interactions of aerodynamic waves generated by the trains. The simulation results reveal that the pressure and drag coefficients of the trains reach a maximum when the two trains intersect at the mid-point of the tunnel and the values of pressure and drag coefficients increase as the train speed and the blockage ratio increase due to the train/tunnel interaction. However, the side force coefficient is dominated by the train/train interaction and its maximum value occurs when the two trains are aligned side by side.

The effect of waving bottom on the fluid surface wave was investigated. Starting from the basic equations of potential flow theory and boundary conditions, we used the multiple scales perturbation method to deduce fluid surface waves satisfy the first-order approximate equation and second-order approximate equation. Under the second-order approximation, the fluid surface waveform was simulated with the Matlab in the presence of different waving bottom form. The results show that there are three solitary waves on the surface of the fluid. With the development of time, the amplitude of each solitary wave has not changed. It seems that they are not affected each other and propagate independently. So it suggests that the waving bottom is effective for maintaining surface wave energy balance income and expenditure in spreading process.

For the large centrifugal fan impeller, its working condition generally is bad, and its geometry generally is complex. So its displacements and stresses distribution are also complex. In this paper, we can obtain the fan impeller’s displacements and stresses distribution accurately through numerical simulation in G4-73 type centrifugal fan impeller using the finite element method software ANSYS. The calculation result shows that the maximum total displacement of the impeller is m, it occurs on the position of the half of the blade near the outlet of the impeller; and the maximum equivalent stress of the impeller is 193 MPa, it occurs on the contacted position of the blade and the shroud near inlet of the impeller. Furthermore, check the impeller strength, the result shows that the strength of the impeller can meet the requirement.

In this paper we contrast the velocity fields of uniform and non-uniform porous filter media in folding-type air filters under different porosity conditions by numerical simulation. In addition, the non-uniformity of those velocity fields are measured and calculated. The results show that the non-uniformity of air flow velocity is related to pressure drop, and regarding the media whose porosity is above 95% (Δ＞95%), an effective way to improve the velocity uniformity and reduce the pressure drop is to increase the porosity of filter media and make the media capture particles evenly.

Summarization: To study the waves and runup/rundown generated by a sliding mass, a numerical simulation model, based on the large-eddy-simulation (LES) approach, was developed. The Smagorinsky subgrid scale model was employed to provide turbulence dissipation and the volume of fluid (VOF) method was used to track the free surface and shoreline movements. A numerical algorithm for describing the motion of the sliding mass was also implemented. To validate the numerical model, we conducted a set of large-scale experiments in a wave tank of 104m long, 3.7m wide and 4.6m deep with a plane slope (1:2) located at one end of the tank. A freely sliding wedge with two orientations and a hemisphere were used to represent landslides. Their initial positions ranged from totally aerial to fully submerged, and the slide mass was also varied over a wide range. The slides were instrumented to provide position and velocity time histories. The time-histories of water surface and the runup at a number of locations were measured. Comparisons between the numerical results and experimental data are presented only for wedge shape slides. Very good agreement is shown for the time histories of runup and generated waves. The detailed three-dimensional complex flow patterns, free surface and shoreline deformations are further illustrated by the numerical results. The maximum runup heights are presented as a function of the initial elevation and the specific weight of the slide. The effects of the wave tank width on the maximum runup are also discussed. Παρουσιάστηκε στο: Journal of Fluid Mechanics

The surface wave of the film with uneven boundary, under supercritical flowage, was analyzed. The control equation for the nonlinear surface wave was obtained by perturbation technique from the potential flow theory; the simulation has been made by pseudo-spectral method. The flow is an incompressible, inviscid fluid with surface tension and different boundary; the results show that the different supercritical flowage has different great effect on the film surface wave, and the simulations results was obviously different from the ones under the resonant case.

The paper presents new numerical simulations of water waves generated by landslides carried out using two numerical models based respectively on the Volumes of Fluids method and on the Smoothed Particle Hydrodynamics. Computations are compared with measurements obtained during a 3D experimental study, used here as benchmark for validating the numerical results. © 2007 World Scientific Publishing Co. Pte. Ltd.

There are six possible types of gene interaction in qualitative traits, namely, complementary, duplicate, cumulative, dominant epistasis, recessive epistasis and inhibiting. In genetic studies, the problem of mapping interactive genes may be met sometimes, but no systematic researches on the methodology and computer software for the mapping of interactive genes have been reported up to date. In this paper, methods for the mapping of interactive genes based on maximum-likelihood estimation and corresponding computer software (IGMapping 1.0) are presented. Computer simulations have shown that the methods proposed can unbiasedly estimate the recombination frequency or linkage distance between a codominant marker and an interactive gene.