scholarly journals Transient Evolution of Inland Freshwater Lenses: Comparison of Numerical and Physical Experiments

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1154
Author(s):  
Rachel Rotz ◽  
Adam Milewski ◽  
Todd C Rasmussen
Keyword(s):  
Numerical Model ◽  
Arabian Peninsula ◽  
Transport Model ◽  
Numerical Models ◽  
Water Levels ◽  
Physical Models ◽  
Laboratory Model ◽  
Arid Environments ◽  
Model Simulations ◽  
Freshwater Lenses

Brackish to saline groundwater in arid environments encourages the development and sustainability of inland freshwater lenses (IFLs). While these freshwater resources supply much-needed drinking water throughout the Arabian Peninsula and other drylands, little is understood about their sustainability. This study presents a numerical model using the SEAWAT programming code (i.e., MODFLOW and the Modular Three-Dimensional Multispecies Transport Model (MT3DMS)) to simulate IFL transient evolution. The numerical model is based on a physical laboratory model and calibrated using results from simulations conducted in a previous study of the Raudhatain IFL in northern Kuwait. Data from three previously conducted physical model simulations were evaluated against the corresponding numerical model simulations. The hydraulic conductivities in the horizontal and vertical directions were successfully optimized to minimize the objective function of the numerical model simulations. The numerical model matched observed IFL water levels at four locations through time, as well as IFL thicknesses and lengths (R2 = 0.89, 0.94, 0.85). Predicted lens degradation times corresponded to the observed lenses, which demonstrated the utility of numerical models and physical models to assess IFL geometry and position. Improved understanding of IFL dynamics provides water-resource exploration and development opportunities in drylands throughout the Arabian Peninsula and elsewhere with similar environmental settings.

A RANS numerical model for cross-shore beach profile evolution

2020 ◽  
Author(s):  
Julio Garcia-Maribona ◽  
Javier L. Lara ◽  
Maria Maza ◽  
Iñigo J. Losada
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Transport Model ◽  
Numerical Models ◽  
Computational Cost ◽  
Physical Modelling ◽  
Computational Effort ◽  
Beach Profile ◽  
Time Step ◽  
Wave Conditions

<p>The evolution of the cross-shore beach profile is tightly related to the evolution of the coastline in both small and large time scales. Bathymetry changes in extreme maritime events can also have important effects on coastal infrastructures such as geotechnical failures of foundations or the modification of the incident wave conditions towards a more unfavourable situation.</p><p>The available strategies to study the evolution of beach profiles can be classified in analytical, physical and numerical modelling. Analytical solutions are fast, but too simplistic for many applications. Physical modelling provides trustworthy results and can be applied to a wide variety of configurations, however, they are costly and time-consuming compared to analytical strategies. Finally,  numerical approaches offer different balances between cost and precision depending on the particular model.</p><p>Some numerical models provide greater precision in the beach profile evolution, but incurring in a prohibitive computational cost for many applications. In contrast, the less expensive ones assume simplifications which do not allow to correctly reproduce significant phenomena of the near-shore hydrodynamics such as wave breaking or undertow currents, neither to predict important features of the beach profile like breaker bars.</p><p>In this work, a new numerical model is developed to reproduce the main features of the beach profile and hydrodynamics while maintaining an affordable computational cost. In addition, it is intended to reduce to the minimum the number of coefficients that the user has to provide to make the model more predictive.</p><p>The model consists of two main modules. Firstly, the already existing 2D RANS numerical model IH2VOF is used to compute the hydrodynamics. Secondly, the sediment transport model modifies the bathymetry according to the obtained hydrodynamics. The new bathymetry is then considered in the hydrodynamic model to account for it in the next time step.</p><p>The sediment transport module considers bedload and suspended transports separately. The former is obtained with empirical formulae. In the later,the distribution of sediment concentration in the domain is obtained by solving an advective-diffusive transport equation. Then, the sedimentation and erosion rates are obtained along the seabed.<br>Once these contributions are calculated, a sediment balance is performed in every seabed segment to determine the variation in its level.</p><p>With the previously described strategy, the resulting model is able to predict not only the seabed changes due to different wave conditions, but also the influence of this new bathymetry in the hydrodynamics, capturing features such as the generation of a breaker bar, displacement of the breaking point or variation of the run-up over the beach profile. To validate the model, the numerical results are compared to experimental data.</p><p>An important novelty of the present model is the computational effort required to perform the simulations, which is significantly smaller than the one associated to existing models able to reproduce the same phenomena.</p>

scholarly journals Numerical Modeling of Flow Field in Morning Glory Spillways and Determining Rating Curve at Different Flow Rates

2016 ◽  
Vol 2 (9) ◽  
pp. 448-457 ◽  
Author(s):  
Mohammad Reza Enjilzadeh ◽  
Ebrahim Nohani
Keyword(s):  
Numerical Model ◽  
Flow Field ◽  
Numerical Modelling ◽  
Relative Error ◽  
Numerical Models ◽  
Discharge Rate ◽  
Morning Glory ◽  
Physical Models ◽  
Rating Curve ◽  
Inlet Conditions

Morning glory spillways with drop inlets are normally employed in dams built on narrow valleys or placed on steep slopes. In Iran, morning glory spillways have been commonly used in large Dam projects such as Sefidrood dam, Alborz dam, and Haraz dam. Physical models should be built to accurately determine hydraulic parameters of the flow and flow field in spillways. Establishment of a physical model involves extravagant costs and conditions that cannot be justified in some cases. Therefore, suitable numerical models can be proposed for such circumstances. Using FLOW3D numerical models, 3-dimensional numerical modelling of the flow was calibrated and validated by experimental information associated with morning glory spillway of Alborz dam and accuracy of numerical modelling was determined by relative error of numerical model. So it was attempted to determine flow pattern and control conditions of morning glory spillways in different modes using boundary conditions, inlet conditions and grid spacing of flow field and project rating curve of morning glory spillways. According to the results of numerical model, relative error of numerical modelling equals 6.4% for calculating discharge rate of the spillways. Numerical modelling error is 7.6% for determining depth parameter of the flow in spillway crest in comparison with experimental results.

A Hybrid (Numerical-physical) Model of the Left Ventricle

2001 ◽  
Vol 24 (7) ◽  
pp. 456-462 ◽  
Author(s):  
G. Ferrari ◽  
M. Kozarski ◽  
C. De Lazzari ◽  
F. Clemente ◽  
M. Merolli ◽  
...  
Keyword(s):  
Numerical Model ◽  
Hybrid Model ◽  
Time Course ◽  
Numerical Models ◽  
Open Loop ◽  
Physical Models ◽  
Gear Pump ◽  
Arterial Tree ◽  
Pump System ◽  
Output Flow

Hydraulic models of the circulation are used to test mechanical devices and for training and research purposes; when compared to numerical models, however, they are not flexible enough and rather expensive. The solution proposed here is to merge the characteristics and the flexibility of numerical models with the functions of physical models. The result is a hybrid model with numerical and physical sections connected by an electro-hydraulic interface - which is to some extent the main problem since the numerical model can be easily changed or modified. The concept of hybrid model is applied to the representation of ventricular function by a variable elastance numerical model. This prototype is an open loop circuit and the physical section is built out of a reservoir (atrium) and a modified windkessel (arterial tree). The corresponding equations are solved numerically using the variables (atrial and arterial pressures) coming from the physical circuit. Ventricular output flow is the computed variable and is sent to a servo amplifier connected to a DC motor-gear pump system. The gear pump, behaving roughly as a flow source, is the interface to the physical circuit. Results obtained under different hemodynamic conditions demonstrate the behaviour of the ventricular model on the pressure-volume plane and the time course of output flow and arterial pressure.

scholarly journals Impact of Temperature on the Moisture Buffering Performance of Palm and Sunflower Concretes

2021 ◽  
Vol 11 (12) ◽  
pp. 5420
Author(s):  
Fathia Dahir Igue ◽  
Anh Dung Tran Le ◽  
Alexandra Bourdot ◽  
Geoffrey Promis ◽  
Sy Tuan Nguyen ◽  
...  
Keyword(s):  
Numerical Model ◽  
Building Materials ◽  
Numerical Models ◽  
Buffering Capacity ◽  
Physical Models ◽  
Embodied Energy ◽  
Problem Analysis ◽  
Simulation Problem ◽  
Interesting Solution ◽  
Moisture Buffering

The use of bio-based materials (BBM) in buildings is an interesting solution as they are eco-friendly materials and have low embodied energy. This article aims to investigate the hygric performance of two bio-based materials: palm and sunflower concretes. The moisture buffering value (MBV) characterizes the ability of a material or multilayer component to moderate the variation in the indoor relative humidity (RH). In the literature, the moisture buffer values of bio-based concretes were measured at a constant temperature of 23 °C. However, in reality, the indoor temperature of the buildings is variable. The originality of this article is found in studying the influence of the temperature on the moisture buffer performance of BBM. A study at wall scale on its impact on the indoor RH at room level will be carried out. First, the physical models are presented. Second, the numerical models are implemented in the Simulation Problem Analysis and Research Kernel (SPARK) suited to complex problems. Then, the numerical model validated with the experimental results found in the literature is used to investigate the moisture buffering capacity of BBM as a function of the temperature and its application in buildings. The results show that the temperature has a significant impact on the moisture buffering capacity of bio-based building materials and its capacity to dampen indoor RH variation. Using the numerical model presented in this paper can predict and optimize the hygric performance of BBM designed for building application.

scholarly journals MODELLING OF A NEARSHORE PLACED SAND MOUND

2012 ◽  
Vol 1 (33) ◽  
pp. 35
Author(s):  
Ernest R. Smith ◽  
Felice D'Alessandro ◽  
Giuseppe Roberto Tomasicchio ◽  
Joseph Z. Gailani
Keyword(s):  
Numerical Model ◽  
Numerical Solutions ◽  
Numerical Models ◽  
Open Water ◽  
Beach Nourishment ◽  
The United States ◽  
Water Levels ◽  
Beach Profile ◽  
Near Shore ◽  
Model C

Nearshore placement of sand is becoming a more popular option in two related types of coastal engineering projects: beach nourishment and inlet dredging. Placing the sand in the nearshore instead of directly on the beach can reduce the costs of a beach nourishment project (Douglass 1995); furthermore, the environmental impact to the beach and dune ecosystem may be perceived to be less for open-water disposal with subsequent migration than for direct placement on the beach. Nearshore placement of sand is also an option in navigation dredging projects for similar reasons. Several design and planning questions relate to the fate of dredged sand placed in the nearshore. Can we economically use profile nourishment, and what is the certainty that a constructed submerged feature will move onshore or remain in place? And if it will move, what is the rate of its movement? Another question concerns how deep material should be placed. In order to answer these questions, together with physical model experiments, several empirical/numerical models have been developed in the past in the United States as a part of the Corps of Engineers ‘Dredging Research Program’ (DRP) (Hands 1991, Larson and Kraus 1992). Hydrodynamic modelling of the nearshore environment has reached a verifiable level of maturity in the last decades as a result of well-defined equations, established numerical solutions and quality laboratory and field data. On the contrary, modelling of sediment transport and beach profile evolution has not yet approached a similar level of accuracy. Most commonly applied models to predict beach profile modifications and to estimate the migration rate of nearshore constructed sand mounds rely on empirical relationships (Douglass 1995). More recently, the numerical model C-SHORE (Kobayashi et al. 2007; Figlus et al. 2011) was developed resulting in simple, practical and accurate code that predicts beach–dune profile evolution over the near-shore region in response to waves, currents and water levels. In the present work, a calibration and verification procedure is considered for the numerical model C-SHORE (Kobayashi et al. 2007) and the empirical model (Douglass 1995).

scholarly journals Analysis of estuarine flood levels based on numerical modelling. The Douro river estuary case study

2019 ◽  
Vol 23 ◽  
pp. 14
Author(s):  
Stênio De Sousa Venâncio ◽  
José Luís Pinho ◽  
José Manuel Vieira ◽  
Paulo Avilez-Valente ◽  
Isabel Iglesias
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Numerical Models ◽  
River Estuary ◽  
Northern Region ◽  
Complete Characterization ◽  
Water Levels ◽  
Flood Events ◽  
Douro River

Estuarine hydrodynamics present intermittent and complex circulation patterns. In this context, from the point of view of the coastal management associated with flood risks in riverine areas, numerical models allow predicting scenarios under specific hypotheses. This work simulates flood events occurring in the Douro river estuary recurring to numerical modelling tools. This estuary, located in the northern region of Portugal, periodically suffered severe flooding, with the associated losses and damages for the local protected landscape areas and hydraulic structures. The occurrence of these events justify the importance of a complete characterization of the areas that present risk of inundation and how they can be affected. A 2D-horizontal numerical model implemented with the Delft3D software was developed for this estuarine region including also the adjacent coastal zone. Available in-situ data were used for model calibration and validation processes. The obtained results are consistent with the in-situ measured water levels, allowing to understand the dynamics of the estuary during flood events. The robustness of the implemented numerical model allows to anticipate flood scenarios effects and associated water levels. The simulations results can then be used for sustainable management of this estuarine zone that presents high social, economic and environmental values.

scholarly journals GRAVEL BEACH PROFILE EVOLUTION IN WAVE AND TIDAL ENVIRONMENTS

2012 ◽  
Vol 1 (33) ◽  
pp. 15
Author(s):  
Mohamad Hidayat Jamal ◽  
David J. Simmonds ◽  
Vanesa Magar
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Large Scale ◽  
Water Levels ◽  
Coarse Grained ◽  
Beach Profile ◽  
Model Simulations ◽  
Parameter Values ◽  
Future Work ◽  
Gravel Beach

This paper reports progress made in modifying and applying the X-Beach code to predict and explain the observed behaviour of coarse grained beaches. In a previous study a comparison of beach profile evolution measured during large scale experiments under constant water level with numerical model simulations was made. This placed particular emphasis on the tendency for onshore transport and profile steepening during calm conditions (Jamal et al., 2010). The present paper extends that investigation to study the influence of the advection of surf processes induced by tidal water level variations effects, on gravel beach profile evolution. The parameter values and numerical model used in the simulation is similar to that presented previously. It is assumed that, to good approximation, the groundwater interface inside the beach follows the tidally modulated water level. The results obtained from the model shows that the model provides reasonable simulations of beach profile change in a tidal environment. In comparison with simulations under stationary water levels, a larger berm is produced in agreement with literature. Finally, good agreement is obtained between the model simulations and an example of field observations from a beach at Milford on Sea, UK. Further developments are outlined for future work.

Solving a harbor accretion problem: the case of Miller and, Îles-de-la-Madeleine, Quebec

1989 ◽  
Vol 16 (6) ◽  
pp. 924-935 ◽  
Author(s):  
Yvon Ouellet ◽  
François Anctil ◽  
Louis Desjardins
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Wave Climate ◽  
Physical Models ◽  
Diffraction Reflection ◽  
East Side ◽  
Littoral Drift ◽  
Reflection Model ◽  
The Impact ◽  
La Madeleine

This paper summarizes a group of studies regarding Millerand harbor, located on the Îles-de-la-Madeleine coast, which blocks most of the local littoral drift. The understanding and quantification of this sedimentological problem was first carried out using numerical models. Various schemes were then tested in two mobile-bed physical models. Finally, the impact of these solutions on the wave climate in the harbor and in the entrance channel was compared using a diffraction–reflection numerical model. The results show that accretion in Millerand harbor will only be controlled by the construction of a breakwater. This breakwater must close the east side of the harbor and must reach at least 2 m depth at its toe. It is also strongly recommended that two groins be built on the east-side beach to control the erosion of the cliff. The results of the diffraction–reflection model finally give some latitude to the harbor planners, as several schemes present satisfactory wave agitation maps. Key words: erosion, accretion, breakwater, diffraction–reflection, harbor, littoral drift, numerical model, physical model, wave hindcasting.

Comparison Between Numerical Modeling and Experimental Testing of a Point Absorber WEC Using Linear Power Take-Off System

2012 ◽  
Author(s):  
Andrew S. Zurkinden ◽  
Morten Kramer ◽  
Mahdi Teimouri Teimouri ◽  
Marco Alves
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Numerical Models ◽  
Experimental Testing ◽  
Irregular Waves ◽  
Laboratory Model ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Wave Conditions ◽  
Energy Converters

Currently, a number of wave energy converters are being analyzed by means of numerical models in order to predict the electrical power generation under given wave conditions. A common characteristic of this procedure is to integrate the loadings from the hydrodynamics, power take-off and mooring systems into a central wave to wire model. The power production then depends on the control strategy which is applied to the device. The objective of this paper is to develop numerical methods for motion analysis of marine structures with a special emphasis on wave energy converters. Two different time domain models are applied to a point absorber system working in pitch mode only. The device is similar to the well-known Wavestar prototype located in the Danish North Sea. A laboratory model has been set up in order to validate the numerical simulations of the dynamics. Wave Excitation force and the response of the device for regular and irregular waves were measured. Good correspondence is found between the numerical and the physical model for relatively mild wave conditions. For higher waves the numerical model seems to underestimate the response of the device due to its linear fluid-structure interaction assumption and linearized equation of motion. The region over which the numerical model is valid will be presented in terms of non-dimensional parameters describing the different wave states.

Sign in / Sign up

Export Citation Format

Share Document