Extensive areas of the earth are covered by unsaturated soils. Besides, construction of fills, embankments and earth dams are related to compacted soils, which are a very widespread class of unsaturated soils, and there are many geotechnical problems with these soils. The unsaturated soil is assumed to be a three-phase porous media with a solid phase and two fluid phases, water and air. Therefore, considerable attempts have been made to explain or to predict shear strength and volume change behaviour of unsaturated soils in terms of effective stress...

The partitioned approach for solving fluid-structure interaction problems is prone to numerical instabilities, often leading to a lack of convergence. Overcoming these challenges requires stabilization techniques and reduced time steps, significantly increasing computational costs. In this study, a monolithic formulation within the Arbitrary Lagrangian-Eulerian (ALE) framework is proposed for analyzing fluid-structure interaction problems, enabling efficient tracking of moving boundaries. The Navier-Stokes equations for unsteady fluid flow and the linear elasticity equations for the structure are solved in a strongly coupled manner. Comparison with the partitioned approach revealed that the average computational time per step in the partitioned method was 51 seconds, while the proposed approach required only 7 seconds, demonstrating its computational efficiency. Furthermore, the proposed method eliminates the added mass effect, enhances solution accuracy, and prevents sudden oscillations observed in the partitioned approach.Additionally, mesh dependency analysis showed that increasing the degrees of freedom from 85,452 to 1,141,027 resulted in only a 2% increase in pressure and displacement, indicating minimal sensitivity to mesh size. This highlights the robustness and efficiency of the proposed method in solving fluid-structure interaction problems.

In this paper a meshless method using exponential basis functions is developed for fluid-structure interaction in liquid tanks undergoing non-linear sloshing. The formulation in the fluid part is based on the use of Navier-Stokes equations, presented in Lagrangian description as Laplacian of the pressure, for inviscid incompressible fluids. The use of exponential basis functions satisfying the Laplace equation leads to a strong form of volume preservation which has a direct effect on the accuracy of the pressure field. In a boundary node style, the bases are used to incrementally solve the fluid part in space and time. The elastic structure is discretized by the finite elements and analyzed by the Newmark method. The direct use of the pressure, as the 䐀 䐀 ential of the acceleration, helps to find the loads acting on the structure in a straight-forward manner. The interaction equations are derived and used in the analysis of a tank with elastic walls. The overall formulation may be implemented simply. To demonstrate the efficiency of the solution, the obtained results are compared with those obtained from a finite elements solution using Lagrangian description. The results show that while the wave height and the oscillations of elastic walls of the two analyses are in good agreement with each other; the use of the proposed meshless analysis not only leads to accurate hydrodynamic pressure but also reduces the computational time to one-eighth of the time needed for the finite e☮ leKmeeynwtso radnsa

We show that many independent scenarios as the ‘accelerated expansion of the universe’, ‘eternal inflation’, ‘eternally oscillating universe’, ‘nonsingular oscillating universe’, and ‘collapse of an oscillating universe’ may occur without modifying the gravity theory or introducing scalar fields of any type. This is achieved by replacing the standard Lagrangian in the Friedmann-Robertson-Walker spacetime model by an exponentially nonstandard Lagrangian which modify the Euler-Lagrange equation although the standard variational approach is used.

Bed-load transport is effective on river bed stability and Morphology. Therefore, modeling this phenomenon is very important in the field of hydraulics engineering. Bed-load transport occurs by saltation at low to medium shear stress and by sheet-flow at high shear stress. In the present paper, the hydrodynamics of transport in thesaltationand sheet-flow regimes under unidirectional flow is studied using a Lagrangian model based on I-SPH method. The fluid and sediment phases are modeled separately as Newtonian and non-Newtonian fluids respectively.Fluid-sediment interaction is modeled using drag force to define interaction mechanism. To calibrate and validate the numerical model, the result is compared with experiments. There is a good agreement between them that illustrates the applicability of the present model in the simulation of both saltation and sheet-flow regimes hydrodynamics.

Overally location problem could be classified as desirable facility location and undesirable facility location. In the undesirable facility location problem contrary to desirable location, facilities are located far from service receiver facilities as much as possible. The problem of locating such facilities is discussed in this paper. This research is focused on the “ not in my backyard” (NIMBY) which refers to the social phenomena in which residents are opposed to locate undesirable facilities around their houses. Examples of such facilities include electric transmission lines and recycling centers. Due to the opposition typically encountered in constructing an undesirable facility, the facility planner should understand the nature of the NIMBY phenomena and consider it as a key factor in the determining facility location. A integer linear model of this problem and a Lagrange relaxation method are proposed in this research. This method relaxes up the hard constraints and adds the constraints to the objective function with a Lagrangian multiplier. To show that the Lagrangian relaxation method is computationally powerful exact solution algorithm and is capable to solve the medium-size problems, the performance of the proposed algorithm is examined by applying it to several test problems.