| 1. |
- Andersson, Anders G., et al.
(författare)
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A study of the location of the entrance of a fishway in a regulated river with CFD and ADCP
- 2012
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Ingår i: Modelling and Simulation in Engineering. - : Hindawi Limited. - 1687-5591 .- 1687-5605. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- Simulation-driven design with computational fluid dynamics has been used to evaluate the flow downstream of a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed, and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations, and the tailrace jet from the turbines is stronger in the simulations. A fishway entrance was included in the simulations, and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed for further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.
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| 2. |
- Kroon, Martin, 1974-
(författare)
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Simulation of cerebral aneurysm growth and prediction of evolving rupture risk
- 2011
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Ingår i: Modelling and Simulation in Engineering. - : Hindawi Limited. - 1687-5591 .- 1687-5605.
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral aneurysms are local expansions of blood vessel walls in the brain blood system. The rupture of an aneurysm is a very severe event associated with a high rate of mortality. When cerebral aneurysms are detected, clinicians need to decide if operation is required. The risk of aneurysm rupture is then compared to the risks associated with the medical intervention. In the present paper, a probabilistic framework for a mechanically based rupture risk assessment of cerebral aneurysms is proposed. The method is based on the assumption that the strength of aneurysmal tissues can be described by a statistical distribution. A structural analysis of the aneurysm in question is performed, and the maximum stress experienced by the aneurysm is compared to the strength distribution. The proposed model was compared with clinical results for ruptured aneurysms in terms of rupture density and accumulated rupture risk as a function of aneurysm size. The model was able to reproduce the clinical results well. The proposed framework may potentially be used under in vivo conditions to predict the risk of rupture for diagnosed aneurysms.
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| 3. |
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| 4. |
- Liu, Qingwei, 1970, et al.
(författare)
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Estimation of Grain Orientation in an Anisotropic Weld by Using a Model of Ultrasonic Propagation in an Inverse Scheme
- 2014
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Ingår i: Modelling and Simulation in Engineering. - : Hindawi Limited. - 1687-5591 .- 1687-5605. ; 2014, s. 11-
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Tidskriftsartikel (refereegranskat)abstract
- The initial step towards a nondestructive technique that estimates grain orientation in an anisotropic weld is presented in this paper. The purpose is to aid future forward simulations of ultrasonic NDT of this kind of weld to achieve a better result. A forward model that consists of a weld model, a transmitter model, a receiver model, and a 2D ray tracing algorithm is introduced. An inversion based on a multiobjective genetic algorithm is also presented. Experiments are conducted for both P and SV waves in order to collect enough data used in the inversion. Calculation is conducted to fulfill the estimation with both the synthetic data and the experimental data. Concluding remarks are presented at the end of the paper.
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| 5. |
- Teng, Penghua, et al.
(författare)
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Studies of Two-Phase Flow at a Chute Aerator with Experiments and CFD Modelling
- 2016
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Ingår i: Modelling and Simulation in Engineering. - : Hindawi Publishing Corporation. - 1687-5591 .- 1687-5605.
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Tidskriftsartikel (refereegranskat)abstract
- The chute aerator of a spillway is a structure in such a sense that air is, in the intense emulsification, entrained into the high-velocity water flow. Correctly predicting the air entrainment and two-phase flow pattern at the aerator would contribute to reliable spillway operation. Based on experimental data, 2D numerical simulations are preformed to predict streamwise air concentrations in the aerated flow, in which a two-fluid model is used. Depending on the air bubble size, relatively good agreement is seen with the experiments in the air cavity zone. The simulations give rise to higher air concentration downstream of the cavity, which is presumably due to underestimation of the interfacial forces in the two-fluid model.
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| 6. |
- Yang, James, et al.
(författare)
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Transient Air-Water Flow and Air Demand following an Opening Outlet Gate
- 2018
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Ingår i: Modelling and Simulation in Engineering. - : HINDAWI LTD. - 1687-5591 .- 1687-5605.
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, the dam-safety guidelines call for an overhaul of many existing bottom outlets. During the opening of an outlet gate, understanding the transient air-water flowis essential for its safe operation, especially under submerged tailwater conditions. Three-dimensional CFD simulations are undertaken to examine air-water flow behaviors at both free and submerged outflows. The gate, hoisted by wire ropes and powered by AC, opens at a constant speed. A mesh is adapted to follow the gate movement. At the free outflow, the CFD simulations and model tests agree well in terms of outlet discharge capacity. Larger air vents lead to more air supply; the increment becomes, however, limited if the vent area is larger than 10 m(2). At the submerged outflow, a hydraulic jump builds up in the conduit when the gate reaches approximately 45% of its full opening. The discharge is affected by the tailwater and slightly by the flow with the hydraulic jump. The flow features strong turbulent mixing of air and water, with build-up and break-up of air pockets and collisions of defragmented water bodies. The air demand rate is several times as much as required by steady-state hydraulic jump with free surface.
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| 7. |
- Zadeh, Navid Shariat, et al.
(författare)
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Service Oriented Integration of Distributed Heterogeneous IT Systems in Production Engineering Using Information Standards and Linked Data
- 2017
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Ingår i: Modelling and Simulation in Engineering. - : Hindawi Publishing Corporation. - 1687-5591 .- 1687-5605.
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Tidskriftsartikel (refereegranskat)abstract
- While design of production systems based on digital models brings benefits, the communication of models comes with challenges since models typically reside in a heterogeneous IT environment using different syntax and semantics. Coping with heterogeneity requires a smart integration strategy. One main paradigm to integrate data and IT systems is to deploy information standards. In particular, ISO 10303 STEP has been endorsed as a suitable standard to exchange a wide variety of product manufacturing data. One the other hand, service-oriented tool integration solutions are progressively adopted for the integration of data and IT-tools, especially with the emergence of Open Services for Lifecycle Collaboration whose focus is on the linking of data from heterogeneous software tools. In practice, there should be a combination of these approaches to facilitate the integration process. Hence, the aim of this paper is to investigate the applications of the approaches and the principles behind them and try to find criteria for where to use which approach. In addition, we explore the synergy between them and consequently suggest an approach based on combination of them. In addition, a systematic approach is suggested to identify required level of integrations and their corresponding approaches exemplified in a typical IT system architecture in Production Engineering.
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