scholarly journals Numerical Study of Landslide-Generated Waves

2004 ◽  
Author(s):  
Gang Yang ◽  
Michael Isaacson
Keyword(s):  
Numerical Study ◽  
Numerical Models ◽  
Domain Boundary ◽  
Time Integration ◽  
Integral Equation Method ◽  
Three Dimensions ◽  
Time Step ◽  
Engineering Applications ◽  
Linear Waves ◽  
Quick Estimate

A time-domain boundary element method is developed to simulate linear waves generated by a wave paddle or a horizontal-moving landslide of an arbitrary profile. In this approach, a time-integration procedure is used to apply the boundary conditions, and the wave field at each time step is solved by an integral equation method based on Green’s theorem. Numerical models in three dimensions are developed to simulate waves generated by landslides. The models were validated against theoretical and experimental results on comparative wavemaker problems. Numerical simulation results on landslide-generated waves demonstrate a number of features of interest. Design curves for engineering applications are also developed for quick estimate of magnitudes of landslide-generated waves in engineering applications.

A Two-Region Model for Gradient Modification of Salt-Gradient Solar Ponds by Radial Injection

1996 ◽  
Vol 118 (1) ◽  
pp. 37-44 ◽  
Author(s):  
G. A. Eghneim ◽  
S. J. Kleis
Keyword(s):  
Turbulence Model ◽  
Field Model ◽  
Numerical Study ◽  
Numerical Models ◽  
Domain Boundary ◽  
Near Field ◽  
Solar Ponds ◽  
Numerical Predictions ◽  
Region Model ◽  
Salt Gradient

A combined experimental and numerical study was conducted to support the development of a new gradient maintenance technique for salt-gradient solar ponds. Two numerical models were developed and verified by laboratory experiments. The first is an axisymmetric (near-field) model which determines mixing and entrainment in the near-field of the injecting diffuser by solving the conservation equations of mass, momentum, energy, and salt. The model assumes variable properties and uses a simple turbulence model based on the mixing length hypothesis to account for the turbulence effects. A series of experimental measurements were conducted in the laboratory for the initial adjustment of the turbulence model and verification of the code. The second model is a one-dimensional far-field model which determines the change of the salt distribution in the pond gradient zone as a result of injection by coupling the near-field injection conditions to the pond geometry. This is implemented by distributing the volume fluxes obtained at the domain boundary of the near-field model, to the gradient layers of the same densities. The numerical predictions obtained by the two-region model was found to be in reasonable agreement with the experimental data.

scholarly journals Modelling thermomechanical ice deformation using a GPU-based implicit pseudo-transient method (FastICE v1.0)

2019 ◽  
Author(s):  
Ludovic Räss ◽  
Aleksandar Licul ◽  
Frédéric Herman ◽  
Yury Y. Podladchikov ◽  
Jenny Suckale
Keyword(s):  
Numerical Models ◽  
Time Integration ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Thermomechanical Coupling ◽  
Transition Zones ◽  
Distributed Memory Machines ◽  
Basal Sliding ◽  
Shear Heating ◽  
Matrix Free

Abstract. Accurate predictions of future sea level rise require numerical models that capture the complex thermomechanical feedbacks in rapidly deforming ice. Shear margins, grounding zones and the basal sliding interface are locations of particular interest where the stress-field is complex and fundamentally three-dimensional. These transition zones are prone to thermomechanical localisation, which can be captured numerically only with high temporal and spatial resolution. Thus, better understanding the coupled physical processes that govern these boundaries of localised strain necessitates a non-linear, full Stokes model that affords high resolution and scales well in three dimensions. This paper’s goal is to contribute to the growing toolbox for modelling thermomechanical deformation in ice by levering GPU accelerators’ parallel scalability. We propose a numerical model that relies on pseudo-transient iterations to solve the implicit thermomechanical coupling between ice motion and temperature involving shear-heating and a temperature-dependant ice viscosity. Our method is based on the finite-difference discretisation, and we implement the pseudo-time integration in a matrix-free way. We benchmark the mechanical Stokes solver against the finite-element code Elmer/Ice and report good agreement among the results. We showcase a parallel version of the solver to run on GPU-accelerated distributed memory machines, reaching a parallel efficiency of 93 %. We show that our model is particularly useful for improving our process-based understanding of flow localisation in the complex transition zones bounding rapidly moving ice.

scholarly journals A Fully Implicit Finite Volume Scheme for a Seawater Intrusion Problem in Coastal Aquifers

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1639
Author(s):  
Abdelkrim Aharmouch ◽  
Brahim Amaziane ◽  
Mustapha El Ossmani ◽  
Khadija Talali
Keyword(s):  
Finite Volume ◽  
Coastal Aquifers ◽  
Nonlinear Partial Differential Equations ◽  
Time Integration ◽  
Mass Conservation ◽  
Coupled System ◽  
Finite Volume Scheme ◽  
Time Step ◽  
Volume Scheme ◽  
Fully Implicit

We present a numerical framework for efficiently simulating seawater flow in coastal aquifers using a finite volume method. The mathematical model consists of coupled and nonlinear partial differential equations. Difficulties arise from the nonlinear structure of the system and the complexity of natural fields, which results in complex aquifer geometries and heterogeneity in the hydraulic parameters. When numerically solving such a model, due to the mentioned feature, attempts to explicitly perform the time integration result in an excessively restricted stability condition on time step. An implicit method, which calculates the flow dynamics at each time step, is needed to overcome the stability problem of the time integration and mass conservation. A fully implicit finite volume scheme is developed to discretize the coupled system that allows the use of much longer time steps than explicit schemes. We have developed and implemented this scheme in a new module in the context of the open source platform DuMu X . The accuracy and effectiveness of this new module are demonstrated through numerical investigation for simulating the displacement of the sharp interface between saltwater and freshwater in groundwater flow. Lastly, numerical results of a realistic test case are presented to prove the efficiency and the performance of the method.

scholarly journals Three-Dimensional Elastodynamic Analysis Employing Partially Discontinuous Boundary Elements

Algorithms ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 129
Author(s):  
Yuan Li ◽  
Ni Zhang ◽  
Yuejiao Gong ◽  
Wentao Mao ◽  
Shiguang Zhang
Keyword(s):  
Side Effect ◽  
Domain Boundary ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Integration Scheme ◽  
Computational Accuracy ◽  
Time Step ◽  
Corner Points ◽  
Discontinuous Elements ◽  
The Time Domain

Compared with continuous elements, discontinuous elements advance in processing the discontinuity of physical variables at corner points and discretized models with complex boundaries. However, the computational accuracy of discontinuous elements is sensitive to the positions of element nodes. To reduce the side effect of the node position on the results, this paper proposes employing partially discontinuous elements to compute the time-domain boundary integral equation of 3D elastodynamics. Using the partially discontinuous element, the nodes located at the corner points will be shrunk into the element, whereas the nodes at the non-corner points remain unchanged. As such, a discrete model that is continuous on surfaces and discontinuous between adjacent surfaces can be generated. First, we present a numerical integration scheme of the partially discontinuous element. For the singular integral, an improved element subdivision method is proposed to reduce the side effect of the time step on the integral accuracy. Then, the effectiveness of the proposed method is verified by two numerical examples. Meanwhile, we study the influence of the positions of the nodes on the stability and accuracy of the computation results by cases. Finally, the recommended value range of the inward shrink ratio of the element nodes is provided.

scholarly journals Statistical Uncertainty of DNS in Geometries without Homogeneous Directions

2021 ◽  
Vol 11 (4) ◽  
pp. 1399
Author(s):  
Jure Oder ◽  
Cédric Flageul ◽  
Iztok Tiselj
Keyword(s):  
Channel Flow ◽  
A Priori ◽  
Time Integration ◽  
Navier Stokes ◽  
Statistical Uncertainty ◽  
Time Step ◽  
Order Of Magnitude ◽  
Averaging Time ◽  
The Individual ◽  
Time Required

In this paper, we present uncertainties of statistical quantities of direct numerical simulations (DNS) with small numerical errors. The uncertainties are analysed for channel flow and a flow separation case in a confined backward facing step (BFS) geometry. The infinite channel flow case has two homogeneous directions and this is usually exploited to speed-up the convergence of the results. As we show, such a procedure reduces statistical uncertainties of the results by up to an order of magnitude. This effect is strongest in the near wall regions. In the case of flow over a confined BFS, there are no such directions and thus very long integration times are required. The individual statistical quantities converge with the square root of time integration so, in order to improve the uncertainty by a factor of two, the simulation has to be prolonged by a factor of four. We provide an estimator that can be used to evaluate a priori the DNS relative statistical uncertainties from results obtained with a Reynolds Averaged Navier Stokes simulation. In the DNS, the estimator can be used to predict the averaging time and with it the simulation time required to achieve a certain relative statistical uncertainty of results. For accurate evaluation of averages and their uncertainties, it is not required to use every time step of the DNS. We observe that statistical uncertainty of the results is uninfluenced by reducing the number of samples to the point where the period between two consecutive samples measured in Courant–Friedrichss–Levy (CFL) condition units is below one. Nevertheless, crossing this limit, the estimates of uncertainties start to exhibit significant growth.

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

Numerical study of multi-dimensional hyperbolic telegraph equations arising in nuclear material science via an efficient local meshless method

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Imtiaz Ahmad ◽  
Aly R. Seadawy ◽  
Hijaz Ahmad ◽  
Phatiphat Thounthong ◽  
Fuzhang Wang
Keyword(s):  
Meshless Method ◽  
Material Science ◽  
Numerical Study ◽  
Research Work ◽  
Time Integration ◽  
Three Dimensional ◽  
Nuclear Material ◽  
Telegraph Equations ◽  
Model Equations ◽  
Derivatives Of

Abstract This research work is to study the numerical solution of three-dimensional second-order hyperbolic telegraph equations using an efficient local meshless method based on radial basis function (RBF). The model equations are used in nuclear material science and in the modeling of vibrations of structures. The explicit time integration technique is utilized to semi-discretize the model in the time direction whereas the space derivatives of the model are discretized by the proposed local meshless procedure based on multiquadric RBF. Numerical experiments are performed with the proposed numerical scheme for rectangular and non-rectangular computational domains. The proposed method solutions are converging quickly in comparison with the different existing numerical methods in the recent literature.

scholarly journals Numerical Modeling of the Interaction of Solitary Waves and Submerged Breakwaters with Sharp Vertical Edges Using One-Dimensional Beji & Nadaoka Extended Boussinesq Equations

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Mohammad H. Jabbari ◽  
Parviz Ghadimi ◽  
Ali Masoudi ◽  
Mohammad R. Baradaran
Keyword(s):  
Solitary Waves ◽  
Numerical Study ◽  
Time Integration ◽  
Boussinesq Equations ◽  
Linear Interpolation ◽  
Reflected Waves ◽  
One Dimensional ◽  
Propagating Waves ◽  
Linear Elements ◽  
Predictor Corrector

Using one-dimensional Beji & Nadaoka extended Boussinesq equation, a numerical study of solitary waves over submerged breakwaters has been conducted. Two different obstacles of rectangular as well as circular geometries over the seabed inside a channel have been considered in view of solitary waves passing by. Since these bars possess sharp vertical edges, they cannot directly be modeled by Boussinesq equations. Thus, sharply sloped lines over a short span have replaced the vertical sides, and the interactions of waves including reflection, transmission, and dispersion over the seabed with circular and rectangular shapes during the propagation have been investigated. In this numerical simulation, finite element scheme has been used for spatial discretization. Linear elements along with linear interpolation functions have been utilized for velocity components and the water surface elevation. For time integration, a fourth-order Adams-Bashforth-Moulton predictor-corrector method has been applied. Results indicate that neglecting the vertical edges and ignoring the vortex shedding would have minimal effect on the propagating waves and reflected waves with weak nonlinearity.

Numerical Study on the Growth and Collapse of a Cavitation Bubble inside a Rigid Cylinder with a Compliant Coating

2014 ◽  
Vol 875-877 ◽  
pp. 1194-1198
Author(s):  
Fardin Rouzbahani ◽  
M.T. Shervani-Tabar
Keyword(s):  
Integral Equation ◽  
Boundary Integral Equation ◽  
Cavitation Bubble ◽  
Numerical Study ◽  
Finite Difference Methods ◽  
Life Time ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Compliant Coating ◽  
Rigid Cylinder

In this paper, growth and collapse of a cavitation bubble inside a rigid cylinder with a compliant coating (a model of humans vessels) is studied using Boundary Integral Equation and Finite Difference Methods. The fluid flow is treated as a potential flow and Boundary Integral Equation Method is used to solve Laplaces equation for velocity potential. The compliant coating is modeled as a membrane with a spring foundation. The effects of the parameters describing the flow and the parameters describing the compliant coating on the interaction between the fluid and the cylindrical compliant coating are shown throughout the numerical results. It is shown that by increasing the compliancy of the coating, the bubble life time is decreased and the mass per unit area has an important role in bubble behavior.

Numerical Study of Corrugated Metal Panels Subjected to Windborne Debris Impacts

2014 ◽  
Vol 626 ◽  
pp. 109-114
Author(s):  
Wen Su Chen ◽  
Hong Hao ◽  
Hao Du
Keyword(s):  
Extreme Event ◽  
Numerical Study ◽  
Numerical Models ◽  
Economic Loss ◽  
Wind Loading ◽  
Windborne Debris ◽  
Study Laboratory ◽  
The Impact ◽  
Metal Panels ◽  
Corrugated Metal

Hurricane, typhoon and cyclone take place more and more often around the world with changing climate. Such nature disasters cause tremendous economic loss and casualty. Various kinds of windborne debris such as compact-like, plate-like and rod-like objects driven by hurricane usually imposes localized impact loading on the structure envelopes such as cladding, wall or roof, etc. The dominant opening in the envelope might cause serious damage to the structures, even collapse. To withstand the impact of such extreme event, the requirements on panel capacity to resist windborne debris impact has been presented in the Australian Wind Loading Code (2011) [1]. Corrugated metal panels are widely used as building envelop. In a previous study, laboratory tests have been carried out to investigate the performance of corrugated metal panels subjected to a 4kg wooden projectile by considering various impact locations, impact velocities and boundary conditions. In this study, numerical models were developed to simulate the responses of the corrugated metal panels subjected to wooden debris impacts by using commercial software LS-DYNA. The predicted data from the numerical simulations were compared with the experimental results. The validated numerical model can be used to conduct intensive numerical simulation to study the failure probabilities of corrugated structural panels subjected to windborne debris impacts.

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