An analysis of hydraulic conductivity scale effects in granite (Full-scale Engineered Barrier Experiment (FEBEX), Grimsel, Switzerland)

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

Download Full-text

A Comparison of Several Strategies to Optimize a Ship’s Aft Body

Journal of Ship Production and Design ◽

10.5957/jspd.2011.27.4.202 ◽

2011 ◽

Vol 27 (04) ◽

pp. 202-211

Author(s):

Auke van der Ploeg

Keyword(s):

Viscous Flow ◽

Scale Effects ◽

Full Scale ◽

Ship Hull ◽

Hull Form ◽

Wake Field ◽

Hull Forms ◽

Definition Of

This paper describes a procedure to optimize ship hull forms, based on double body viscous flow computations with PARNASSOS. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. One of the object functions is an estimate of the required power. In this paper we will focus on how to improve this estimate, by using the B-series of propellers. Results of systematic variations applied to the VIRTUE tanker together with scale effects in the computed trends will be discussed. In addition, we will demonstrate how the techniques discussed in this paper can be used to design a model that has a wake field that strongly resembles the wake of a given containership ship at full scale.

Download Full-text

Scale effects and full-scale ship hydrodynamics: A review

Ocean Engineering ◽

10.1016/j.oceaneng.2021.110496 ◽

2022 ◽

Vol 245 ◽

pp. 110496

Author(s):

Momchil Terziev ◽

Tahsin Tezdogan ◽

Atilla Incecik

Keyword(s):

Scale Effects ◽

Full Scale ◽

Ship Hydrodynamics

Download Full-text

Hydraulic Conductivity and Scale Effects Investigation in Basalt in the Dam Area of Xiluodu Hydroelectric Station, Jinshajiang River, China

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.2123 ◽

2013 ◽

Vol 405-408 ◽

pp. 2123-2129

Author(s):

Yuan Yao Li ◽

Rong Lin Sun ◽

Ren Quan Chen

Keyword(s):

Hydraulic Conductivity ◽

Scale Effects ◽

Fractured Rock ◽

Water Pressure ◽

Hydroelectric Station ◽

Tracer Test ◽

Test Results ◽

Hydraulic Test ◽

Water Seepage ◽

Pressure Tests

Hydraulic conductivity (K) and scale effects in basalt in the dam area of Xiluodu hydroelectric station were investigated by three kinds of field hydraulic tests with different test scale, 2608 water pressure tests in single borehole, 54 water seepage tests in adit and groundwater tracer test. Statistical results show the high heterogeneity of fractured rock and K difference between two neighboring test intervals are often more than two orders of magnitude. However, there is a strong decreasing trend of hydraulic conductivity with the increase of vertical depth. Moreover, these three kinds of hydraulic test results demonstrate that hydraulic conductivity increases with the increase of test scale in heterogeneous basalt and the heterogeneous degree of K decreases with the increase of test scale. K from water seepage test in adit, with the test scale of 1-2 m, is dispersed from 0.00024 m/d to 3.46 m/d. K from water pressure test in single borehole, with the test scale of 4-7 m, is 0.0002-1.04 m/d. K from groundwater tracer test, with the test scale of 70-145 m, is concentrated between 0.46 m/d and 2.1 m/d. High heterogeneity of fractured rock and multi-level of fractures are thought as the major reason resulted in scale effects of hydraulic conductivity.

Download Full-text

A discussion of scale effects on hydraulic conductivity at a granitic site (El Berrocal, Spain)

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts ◽

10.1016/0148-9062(96)86929-4 ◽

1996 ◽

Vol 33 (3) ◽

pp. A110

Keyword(s):

Hydraulic Conductivity ◽

Scale Effects

Download Full-text

Model-Scale and Full-Scale CFD Calculations for Current Loads on Semi-Submersible

Volume 7: CFD and VIV; Offshore Geotechnics ◽

10.1115/omae2011-49204 ◽

2011 ◽

Cited By ~ 2

Author(s):

Arjen Koop ◽

Alexei Bereznitski

Keyword(s):

Wind Tunnel ◽

Scale Effects ◽

Full Scale ◽

Grid Resolution ◽

Wind Tunnel Experiments ◽

Force Coefficients ◽

Model Scale ◽

Coarse Grids

In this paper results of CFD calculations with the MARIN in-house code ReFRESCO are presented for the JBF-14000 Semi-Submersible designed by Huisman Equipment BV. The objective of the CFD calculations is to investigate the applicability, the costs and the accuracy of CFD to obtain the current coefficients of a semi-submersible for all headings. Furthermore, full scale CFD calculations are carried out to investigate possible scale effects on the current coefficients. An extensive verification study has been carried for the model-scale current loads on a semi-submersible using 10 different grids of different grid type for 3 different headings, i.e. 180, 150 and 90 degrees. These headings represent the main different flow regions around the semi-submersible. The CFD results are compared with the results from wind tunnel experiments and tests in the Offshore Basin for a range of current headings. The results for the force coefficients are not very dependent on grid resolution and grid type. The largest differences found are less than 10% and these are obtained for CX results for 180 degrees. For the results obtained on the same grid type the results change less than 4% when the grid is refined. These verification results give good confidence in the CFD results. For the angles with larger forces, i.e. the range [180:130] for CX and the range [150:90] for CY the CFD results are within 12% or better from the experiments. Full-scale force coefficients are calculated using 5 subsequently refined grids for three different headings, i.e. 180, 150 and 90 degrees. Scale effects should only be determined when the effect of grid refining is investigated. The trend of the force coefficients when refining the grid, can be different for model-scale and full-scale. The use of coarse grids can lead to misleading conclusions. On average the full-scale values are approximately 15–20% lower than for model-scale. However, larger differences for a number of angles do exist.

Download Full-text

Experimental Study of Containment Boom Behavior in Waves

Marine Technology and SNAME News ◽

10.5957/mt1.1997.34.1.24 ◽

1997 ◽

Vol 34 (01) ◽

pp. 24-30

Author(s):

Michael S. Bruno ◽

Robert L. Van Dyck

Keyword(s):

Scale Effects ◽

Weight Ratio ◽

Breaking Waves ◽

Full Scale ◽

Irregular Waves ◽

Generic Model ◽

Open Sea ◽

Scale Breaking ◽

Heave Motion ◽

Testing Instruments

An effort to assess containment boom performance in waves is described. New model testing instruments and procedures have been developed to provide a direct measure of boom heave response to wave excitation at several points along the boom. Measurements have been made in reproducible regular, irregular and breaking waves for various generic model boom configurations over a range of wave characteristics, boom buoyancy/weight ratios, and towing speeds. A model scale of 1/8 allows for tests in regular waves up to 12 ft high full scale at 12:1 length/height ratio and irregular waves with significant heights of up to 8 ft full scale. Breaking waves equivalent to over 6 ft height above mean water level are also generated. Measurements include total towing force and heave motion at four locations along each boom. The results of tests of three different size models all scaled to the same 4 ft high prototype boom show no significant scale effects on heave response to the various types of waves. Drag differences found among the models are attributable to differences in full scale lengths, as well as buoyancy/weight ratios. A buoyancy/weight ratio of 10 or greater was found to improve heave conformance with waves at optimum towing speeds of about 0.5 knot. Short wavelength waves, requiring the highest frequency response, are shown to be the most difficult conformance problem. Of particular concern is the fact that a catenary tow shape focuses waves near the vertex, thereby amplifying the wave height and causing excessive motions near the center of the boom. For this reason, light weight, highly flexible booms with maximum buoyancy/weight ratio and sufficient freeboard are recommended for open sea operations.

Download Full-text

A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System

Journal of Ship Research ◽

10.5957/jsr.2016.60.1.14 ◽

2016 ◽

Vol 60 (01) ◽

pp. 14-29 ◽

Cited By ~ 1

Author(s):

Leixin Ma ◽

Ke Hu ◽

Shixiao Fu ◽

Torgeir Moan ◽

Runpei Li

Keyword(s):

Hybrid Method ◽

Hydrodynamic Force ◽

Scale Effects ◽

Fish Farming ◽

Full Scale ◽

Hydrodynamic Models ◽

Load Models ◽

Hydroelastic Analysis ◽

Net Cages ◽

Hydroelastic Response

Because of scale effects and inappropriate hydrodynamic models, the nonlinear hydroelastic response of net cages used for fish-farming cannot be analyzed precisely with traditional model testing or combinations of finite element methods (FEMs) and load models. In this study, an innovative hybrid method is proposed to determine the hydroelastic response of full-scale floater-and-net systems more accurately. In this method, the net for the fish cage was vertically and peripherally divided into similar interconnected sections with different hydrodynamic parameters, which were assumed to be uniformly distributed over each section. A model of a typical section was subjected to various towing velocities, oscillation periods, and amplitudes in a towing tank to simulate the potential motions of all sections in the net under various currents, waves, and floater movements. By analyzing the measured hydrodynamic force from this test section, a hydrodynamic force database for a typical net section under various currents, waves, and floater motions was built. Finally, based on an FEM, the modified Morison equation and the hydrodynamic force database, the hydroelastic behavior of the full-scale fish cage was calculated with an iterative scheme. It is demonstrated that this hybrid method is able to produce correct hydroelastic response for both steady and oscillatory flows. The hydroelastic response of a two-dimensional example of a full-length net panel with steady currents and floater oscillations was studied in detail.

Download Full-text