Abed A.A.,Aalto University |
Laitinen M.,Numerola Oy |
Lamsa J.,University of Jyväskylä |
Harjupatana T.,University of Jyväskylä |
And 2 more authors.
E3S Web of Conferences | Year: 2016
As a first step towards modelling the coupled Thermo-Hydro-Mechanical-Chemical (THMC) behaviour of bentonite, the Barcelona Basic Model (BBM) has been implemented into Numerrinfinite element code. This model has beenfully coupled with the single phase flow equation for unsaturated soils which models liquid water transport. Suction obtained from solving the flow equation is used as an input for the BBM model and the volumetric deformations from the mechanical analysis are used to update the pore water pressure field. As an alternative, BBM is used alongside the Kröhn's model which assumes that bentonite re-saturation is mainly driven by water vapour diffusion. The paper simulates one dimensional infiltration test on MX-80bentonite with both implemented modelsfor water transport and compares the results withthose from a laboratory experiments based on X-ray tomography. The numerical results of the simulations are similar despite taking into account different physical phenomena. © 2016 The Authors.
Olin M.,VTT Technical Research Center of Finland |
Rasilainen K.,VTT Technical Research Center of Finland |
Itala A.,VTT Technical Research Center of Finland |
Pulkkanen V.-M.,VTT Technical Research Center of Finland |
And 9 more authors.
VTT Tiedotteita - Valtion Teknillinen Tutkimuskeskus | Year: 2011
In the report main results form a KYT2010 programme's project Coupled behaviour of bentonite buffer (PUSKURI) are presented. In THC modelling, Aku Itälä made and published his Master of Science Thesis. Itälä was able to successfully model the LOT-experiment. Additionally, he also listed problems and development proposals for THC-modelling of bentonite buffer. VTT and Numerola created in collaboration a model coupling saturation, diffusion and cation exchange; the model was implemented and tested in Numerrin, COMSOL and TOUGHREACT. Petri Jussila's PhD THM-model was implemented into COMSOL to facilitate further development. At GTK, the mineralogical characterisation of bentonite was planned. The previous THM model (Jussila's model) including only small deformations was successfully generalized to finite deformations in way at least formally preserving the original formalism. It appears that the theory allows also a possibility to include finite plastic deformations in the theory. In order to measure the relevant mechanical properties of compacted bentonite, two different experiments, namely hydrostatic compression experiment and one-dimensional compression experiment were designed. In the hydrostatic compression experiment, a cylindrical sample of compacted bentonite covered with liquid rubber coating is placed in the sample chamber equipped with a piston. The same device was also used in one-dimensional compression experiment. X-ray microtomographic techniques were used in order to study the basic mechanisms of water transport in bentonite. The preliminary results indicate that in the present experimental set-up, water transport is dominated by a dispersive mechanism such as diffusion of vapour in gas phase or diffusion of water in solid phase. Copyright © VTT 2011.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: NMP.2013.1.4-1 | Award Amount: 4.22M | Year: 2014
Accurate design and modeling of nano-enabled systems requires a multi-scale simulation approach that can link phenomena on the nano-, micro-, meso-, and macroscales. Numerous simulation methods and tools are available for describing a material accurately and efficiently on each of the scales separately. In addition, several approaches for linking and coupling various hierarchal scales are also available. However, an integrated multi-scale simulation framework that allows a seamless and efficient coupling of various scales and methods is still lacking. The main goal of the present consortium is to develop an integrated multi-scale modeling environment for nano-materials and system design. The tools will be formed mainly by augmenting existing open-source and commercial simulation tools and supplementing them with sophisticated interface libraries that allow flow of information from one component to the other and from one scale to another. The simulation environment will also act as a platform for harmonizing and accelerating the development of new simulation modules by providing interface libraries to powerful pre- and postprocessing tools and to computational modules, which can be integrated and readily reused in new applications. The efficiency of the new developed simulation environment specifically for shortening the development process and time to discover novel nano-enabled products will be demonstrated through a proof-of-concept design of novel simulation tools for micro- and nanofluidic devices.
Airaksinen T.,University of Jyväskylä |
Heikkola E.,Numerola Oy |
Toivanen J.,Stanford University
Journal of Computational Acoustics | Year: 2011
A numerical method for optimizing the local control of sound in a stochastic domain is developed. A three-dimensional enclosed acoustic space, for example, a cabin with acoustic actuators in given locations is modeled using the finite element method in the frequency domain. The optimal local noise control signals minimizing the least square of the pressure field in the silent region are given by the solution of a quadratic optimization problem. The developed method computes a robust local noise control in the presence of randomly varying parameters such as variations in the acoustic space. Numerical examples consider the noise experienced by a vehicle driver with a varying posture. In a model problem, a significant noise reduction is demonstrated at lower frequencies. © 2011 IMACS.
Madetoja E.,University of Eastern Finland |
Tarvainen P.,Numerola Oy
Structural and Multidisciplinary Optimization | Year: 2010
Simulation-based optimization for industrial process lines is discussed in this paper. Our approach combines multidisciplinary modeling, modern sensitivity analysis methodology as well as multiobjective optimization by means of object-oriented software design principles. As a result, a simulation and optimization approach that can be extended and modified due to users' needs can be developed. Our approach is illustrated by a real-world example from papermaking industry. © 2009 Springer-Verlag.
Itala A.,VTT Technical Research Center of Finland |
Laitinen M.,Numerola Oy |
Tanhua-TYRKKO M.,VTT Technical Research Center of Finland |
Olin M.,VTT Technical Research Center of Finland
Nuclear Technology | Year: 2014
The bentonite barrier is an essential part of a safe spent fuel repository in granitic bedrock. One of the most important safety functions of bentonite buffer is to limit groundwater flow so that all mass transport takes place by diffusion. In this work a new mathematical model was developed to define the transport of ions inside the bentonite, where there are bound interlayer water and free extra layer water and sorption capability. This model is tested in a specified geometry and calculated by two numerical platforms-Numerrin and COMSOL Multiphysics-and compared to the original TOUGHREACT model. The model comparison was not a straightforward task because of different approaches in the model setup. Therefore, all the equations are written down, and parameterization is done to create model descriptions near each other. The developed model adapts easily, and there are many new ideas to be tested in bridging the gap between performance assessment and real systems.