scholarly journals Comparison of Hydrodynamics Simulated by 1D, 2D and 3D Models Focusing on Bed Shear Stresses

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 226 ◽  
Author(s):  
Kurt Glock ◽  
Michael Tritthart ◽  
Helmut Habersack ◽  
Christoph Hauer
Keyword(s):  
Flow Resistance ◽  
Numerical Models ◽  
3D Models ◽  
Water Levels ◽  
Shear Stresses ◽  
Flow Conditions ◽  
Empirical Formulas ◽  
2D And 3D ◽  
Bed Shear Stresses ◽  
Measured Water

For centuries, scientists have been attempting to map complex hydraulic processes to empirical formulas using different flow resistance definitions, which are further applied in numerical models. Now questions arise as to how consistent the simulated results are between the model dimensions and what influence different morphologies and flow conditions have. For this reason, 1D, 2D and 3D simulations were performed and compared with each other in three study areas with up to three different discharges. A standardized, relative comparison of the models shows that after successful calibration at measured water levels, the associated 2D/1D and 3D/1D ratios are almost unity, while bed shear stresses in the 3D models are only about 62–86% of the simulated 1D values and 90–100% in the case of 2D/1D. Reasons for this can be found in different roughness definitions, in simplified geometries, in different calculation approaches, as well as in influences of the turbulence closure. Moreover, decreasing 3D/1D ratios of shear stresses were found with increasing discharges and with increasing slopes, while the equivalent 2D/1D ratios remain almost unchanged. The findings of this study should be taken into account, particularly in subsequent sediment transport simulations, as these calculations are often based on shear stresses.

scholarly journals The geometric parameters of plants on the spur dykes in a selected section of the Odra River

2018 ◽  
Vol 45 ◽  
pp. 00110
Author(s):  
Magda Hudak
Keyword(s):  
Water Surface ◽  
Flow Resistance ◽  
Water Levels ◽  
Flow Conditions ◽  
Plant Structure ◽  
Central Section ◽  
Quantitative Characteristics ◽  
Odra River ◽  
The Impact ◽  
Resistance Coefficients

Spur dykes are structures for regulating rivers. They are designed for medium water levels, when spur dyke tops are above the water surface. In the central section of the Odra River the water level is changeable, and the spur dykes work in different hydrological conditions: as non-submerged and submerged. Correct recognition of the plant structure growing on the spur dykes is of great importance in the context of the subsequent allocation of its measure related to the hydraulic action, among others coefficients of resistance of plant zones and refers mainly to grasses. In hydraulic calculations, it is required to determine the value of flow resistance coefficients. In such a departure, the flow is omitted in the area occupied by vegetation. Therefore, it is necessary to know the quantitative characteristics of overgrowth. Vegetation should be presented in the form of a model reflecting the impact of plants growing on the spur dykes and their impact on the water flow conditions in the river. Literature data are not very numerous and are still awake unsatisfied. The paper presents the results of research on the density of vegetation on the Odra River in the Nowa Sól region.

Advances in understanding localised variations in deformation experiments using numerical models

2020 ◽  
Author(s):  
Sebastian Cionoiu ◽  
Lucie Tajčmanová ◽  
Lyudmila Khakimova
Keyword(s):  
Grain Size ◽  
Phase Transitions ◽  
Subduction Zones ◽  
Numerical Models ◽  
3D Models ◽  
Rock Properties ◽  
Stress And Strain ◽  
Transition Distribution ◽  
Pressure Stress ◽  
2D And 3D

<p>Phase transitions affect the physical properties of rocks (e.g. rheology) and control geodynamic processes at different spatial and time scales. However, the influence of deformation on phase transitions and their coupling is not well understood. <br>Previous experiments, with both assembly-induced and additionally placed mechanical heterogeneities, have shown patterns in the phase transition distribution. Numerical modelling (2D, viscous finite difference models) have been used to correlate the experimental observations with the mechanic stress state. The locally increased mean stress in the models shows the best correlation with the formation of high-pressure polymorphs in experiments (Cionoiu et al. 2019).<br>Besides the distribution of polymorphs, grain-size and deformation patterns also vary across the samples due to stress, strain and pressure variations. To better understand the mechanisms contributing to these variations, we used advanced numerical models (3D, viscoelastic) to calculate the local distribution of first order parameters as pressure, stress and strain. The modelled stress and strain patterns are compared to the experimentally produced phase transformation distribution and previous (2D) modelling results. The 2D and 3D models differ partially regarding the quantification of local stresses – an effect that mainly depends on sample geometry (coaxial vs. general-shear). However, the qualitative fit between experiments, 2D and 3D models persists (i.e. the localisation of increased stresses or strain).<br>This contribution shows how numerical models, that closely represent the sample, can further improve the understanding of processes occurring in deformation experiments. Our new results emphasize that mechanically-induced stress-variations influence the grain-size and mineralogy of rocks which feeds back on their rheology.</p><p>References: <br>Cionoiu, S., Moulas, E. & Tajčmanová, L. Impact of interseismic deformation on phase transformations and rock properties in subduction zones. Sci Rep 9, 19561 (2019)</p>

scholarly journals SHIP-GENERATED WAVES OVER A COMPLEX BATHYMETRY

2018 ◽  
pp. 35
Author(s):  
Björn Almström ◽  
Magnus Larson ◽  
Lars Granath ◽  
Hans Hanson
Keyword(s):  
Numerical Models ◽  
Water Levels ◽  
Empirical Formulas ◽  
Wave Regime ◽  
Ship Waves ◽  
Ship Wave ◽  
Energy Environment ◽  
Length Width ◽  
Stockholm Archipelago ◽  
New Formula

Problems related to shipping have increased worldwide during the last decades as a result of more traffic travel-ling at higher speeds and using larger vessels. When ships move in a restricted fairway they generate primary (drawdown) and secondary (transverse and divergent) waves (Bertram 2000) that often cause adverse impact to adjacent shores. An example of this is the Furusund fairway in Sweden, which since the 1980’s has experienced increased traffic and larger ships. This has resulted in a loss of natural fine sediment habitats along the shores as well as structural damages to piers and jetties (Granath 2015). Furusund is an important fairway into Stockholm, the capital of Sweden, and is located about 25 km north of the city within the Stockholm archipelago. It is mainly trafficked by large ferries (length/width/draft: 200x30x7m). The wind-wave regime in the fairway can be described as a low-energy environment, due to the short fetches and no swell. Hence, ship waves have a significant impact on the shores in terms of bed and bank erosion. This study aims at determining the primary ship wave characteristics and their relationship to ship properties and bathymetric conditions in the Furusund fairway. Measured water levels were collected for this purpose during three months at three locations. Existing empirical formulas for drawdown are evaluated based on the measurements and compared with a new formula derived for the specific fairway. The results are used for designing nature-based protection against ship-generated waves along the shores and to validate analytical and numerical models that can be employed for ship wave generation and propagation.

Impact of vegetation on flow in a lowland stream during the growing season

Biologia ◽  
2017 ◽  
Vol 72 (8) ◽  
Author(s):  
Yvetta Velísková ◽  
Renáta Dulovičová ◽  
Radoslav Schügerl
Keyword(s):  
Water Depth ◽  
Flow Resistance ◽  
Aquatic Vegetation ◽  
Growing Season ◽  
Water Levels ◽  
Roughness Coefficient ◽  
Flow Conditions ◽  
Channel Network ◽  
Vegetation Impact ◽  
The Subject

AbstractVegetation growing in the water along watercourses has been the subject of several studies since it was recognized that it could have a significant impact on the water flow. It may increase resistance to flow and cause higher water levels. Also, it has an effect on the velocity profiles. Previous investigations on the flow of water through emergent vegetation have shown different results. The purpose of this paper is to investigate, and determine how aquatic vegetation influences flow resistance, water depth and discharge in the Chotárny channel at the Žitný Ostrov area. This area is part of the Danube Lowland (south-west of Slovakia). The channel network at the Žitný Ostrov region was built up for drainage and also to provide irrigation water. The Chotárny channel is one of three main channels of this network. Measurements performed during six years at this channel were used for an evaluation of vegetation impact on flow conditions. The roughness coefficient was used as one way of quantifying this impact. The results show variation of this parameter during the growing season. Vegetation causes resistance to flow; it reduces flow velocities, discharge and increases water depth.

scholarly journals Techniques Used for Eye Gaze Interfaces and Survey

2015 ◽  
Vol 1 (6) ◽  
pp. 276
Author(s):  
Maria Rashid ◽  
Wardah Mehmood ◽  
Aliya Ashraf
Keyword(s):  
Eye Tracking ◽  
Eye Gaze ◽  
3D Models ◽  
Image Process ◽  
Usability Problems ◽  
Software Algorithms ◽  
Pupil Detection ◽  
Eye Movement Tracking ◽  
2D And 3D ◽  
Movement Tracking

Eye movement tracking is a method that is now-a-days used for checking the usability problems in the contexts of Human Computer Interaction (HCI). Firstly we present eye tracking technology and key elements.We tend to evaluate the behavior of the use when they are using the interace of eye gaze. Used different techniques i.e. electro-oculography, infrared oculography, video oculography, image process techniques, scrolling techniques, different models, probable approaches i.e. shape based approach, appearance based methods, 2D and 3D models based approach and different software algorithms for pupil detection etc. We have tried to compare the surveys based on their geometric properties and reportable accuracies and eventually we conclude this study by giving some prediction regarding future eye-gaze. We point out some techniques by using various eyes properties comprising nature, appearance and gesture or some combination for eye tracking and detection. Result displays eye-gaze technique is faster and better approach for selection than a mouse selection. Rate of error for all the matters determines that there have been no errors once choosing from main menus with eye mark and with mouse. But there have been a chance of errors when once choosing from sub menus in case of eye mark. So, maintain head constantly in front of eye gaze monitor.

Point-of-Care Diagnostic Assays and Novel Preclinical Technologies for Hemostasis and Thrombosis

2021 ◽  
Vol 47 (02) ◽  
pp. 120-128
Author(s):  
Christina Caruso ◽  
Wilbur A. Lam
Keyword(s):  
Point Of Care ◽  
Healing Process ◽  
Coagulation Factors ◽  
Wound Healing Process ◽  
Shear Stresses ◽  
Flow Conditions ◽  
Novel Technologies ◽  
Clinical Consequences ◽  
Complex Wound ◽  
Reproducible Analysis

AbstractHemostasis is a complex wound-healing process involving numerous mechanical and biochemical mechanisms and influenced by many factors including platelets, coagulation factors, and endothelial components. Slight alterations in these mechanisms can lead to either prothrombotic or bleeding consequences, and such hemostatic imbalances can lead to significant clinical consequences with resultant morbidity and mortality. An ideal hemostasis assay would not only address all the unique processes involved in clot formation and resolution but also take place under flow conditions to account for endothelial involvement. Global assays do exist; however, these assays are not flow based. Flow-based assays have been limited secondary to their large blood volume requirements and low throughput, limiting potential clinical applications. Microfluidic-based assays address the aforementioned limitations of both global and flow-based assays by utilizing standardized devices that require low blood volumes, offer reproducible analysis, and have functionality under a range of shear stresses and flow conditions. While still largely confined to the preclinical space, here we aim to discuss these novel technologies and potential clinical implications, particularly in comparison to the current, commercially available point-of-care assays.

scholarly journals Fucoxanthin Holds Potential to Become a Drug Adjuvant in Breast Cancer Treatment: Evidence from 2D and 3D Cell Cultures

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4288
Author(s):  
Fernanda Malhão ◽  
Ana Catarina Macedo ◽  
Carla Costa ◽  
Eduardo Rocha ◽  
Alice Abreu Ramos
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
3D Models ◽  
Anticancer Activities ◽  
Cytotoxic Effects ◽  
3D Cultures ◽  
3D Cell Cultures ◽  
Tumoral Cell ◽  
Microscopy Techniques ◽  
2D And 3D

Fucoxanthin (Fx) is a carotenoid derived from marine organisms that exhibits anticancer activities. However, its role as a potential drug adjuvant in breast cancer (BC) treatment is still poorly explored. Firstly, this study investigated the cytotoxic effects of Fx alone and combined with doxorubicin (Dox) and cisplatin (Cis) on a panel of 2D-cultured BC cell lines (MCF7, SKBR3 and MDA-MB-231) and one non-tumoral cell line (MCF12A). Fucoxanthin induced cytotoxicity against all the cell lines and potentiated Dox cytotoxic effects towards the SKBR3 and MDA-MB-231 cells. The combination triggering the highest cytotoxicity (Fx 10 µM + Dox 1 µM in MDA-MB-231) additionally showed significant induction of cell death and genotoxic effects, relative to control. In sequence, the same combination was tested on 3D cultures using a multi-endpoint approach involving bioactivity assays and microscopy techniques. Similar to 2D cultures, the combination of Fx and Dox showed higher cytotoxic effects on 3D cultures compared to the isolated compounds. Furthermore, this combination increased the number of apoptotic cells, decreased cell proliferation, and caused structural and ultrastructural damages on the 3D models. Overall, our findings suggest Fx has potential to become an adjuvant for Dox chemotherapy regimens in BC treatment.

scholarly journals Time Scale for Scour Beneath Pipelines Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Current

2021 ◽  
Vol 9 (2) ◽  
pp. 114
Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong
Keyword(s):  
Time Scale ◽  
Current Flow ◽  
Irregular Waves ◽  
Wave Crest ◽  
Random Wave ◽  
Random Waves ◽  
Flow Conditions ◽  
Regular Waves ◽  
Nonlinear Random Waves ◽  
2D And 3D

This article derives the time scale of pipeline scour caused by 2D (long-crested) and 3D (short-crested) nonlinear irregular waves and current for wave-dominant flow. The motivation is to provide a simple engineering tool suitable to use when assessing the time scale of equilibrium pipeline scour for these flow conditions. The method assumes the random wave process to be stationary and narrow banded adopting a distribution of the wave crest height representing 2D and 3D nonlinear irregular waves and a time scale formula for regular waves plus current. The presented results cover a range of random waves plus current flow conditions for which the method is valid. Results for typical field conditions are also presented. A possible application of the outcome of this study is that, e.g., consulting engineers can use it as part of assessing the on-bottom stability of seabed pipelines.

Development of an Intelligent CAD System for Involute Cylindrical Gear Cutting Tools

2014 ◽  
Vol 532 ◽  
pp. 249-252
Author(s):  
Ying Hua Liao ◽  
Gao Jun Liu ◽  
Xiang Guo Sun
Keyword(s):  
Expert Knowledge ◽  
Cutting Tools ◽  
3D Models ◽  
Tool Design ◽  
Cylindrical Gear ◽  
Intelligent Cad ◽  
Forward Reasoning ◽  
Cad System ◽  
Gear Cutting ◽  
2D And 3D

An intelligent CAD system for Involute cylindrical gear cutting tools is developed by VC++ and SQL server, and it includes four modules, such as user interface, instance query, intelligent gear tool design and database. The intelligent gear tool design is the key to the intelligent CAD system, and it is based on the forward reasoning production system, and as the Intelligent reasoning technology is used for gear tool design, a lots of expert knowledge could be made full use of. The design results by the developed intelligent CAD system are more reasonable than those by a traditional CAD system, and the efficiency and quality of the gear tool design also could be improved. The developed intelligent CAD system supports both 2D and 3D models, which can lay foundation for CAD/CAE/CAM integration of gear cutting tools.

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