Verifikationsmethodik für die rechnerische Windtechnik Vorhersage von Windlasten an Tragwerken

In this thesis, a new credibility assessment framework is developed for computational wind engineering (CWE) simulations. The framework is mainly developed for testing code implementation correctness and estimation of the discretization uncertainty for eddy-resolving, and unsteady simulations. The framework is composed of two main milestones. First, a modular and flexible procedure for code verification is developed with the ability of testing black box codes. The code verification procedure focuses on the consistency of the code implementation and convergence of field variables. The procedure for code verification consists of analytical benchmarks, either exact or manufactured, with increasing complexity to test the implementation of each term in the Navier-Stokes equation. Second, the credibility assessment framework has a guideline for the quantification of discretization error/uncertainty. More precisely, guidelines are defined for solution verification. The discretization error/uncertainty estimation is based on Richardson Extrapolation approach. A solution biased uncertainty estimator is used to account for using unstructured grids, non-uniform refinement, and non-asymptotic solutions. The newly developed framework has a new definition for the measurement of grid size, handling simulation data with anomalous behavior, and for the safety factor definition in the uncertainty quantification of the discretization error. The assessment methodology is suited to both well- and ill-behaved sequences of simulations. The performance of the assessment methodology is checked with a glimpse on validation with experimental data. Finally, it can be concluded that the developed verification methodology is highly qualified to judge the quality of CWE simulations. Moreover, the generality and modularity of the framework makes it applicable to any software environment regardless of the discretization scheme. Consequently, the methodology encourages further research on the identification of the reliability of CWE simulations.In dieser Arbeit wird ein neues Rahmenwerk zur Glaubwürdigkeitsbewertung für rechnergestützte Windsimulationen (CWE) entwickelt. Der Rahmen wird hauptsächlich für die Prüfung der Korrektheit der Code-Implementierung und die Abschätzung der Diskretisierungsunsicherheit für wirbelauflösende und instationäre Simulationen entwickelt. Das Framework besteht aus zwei Hauptmeilensteinen. Erstens wird ein modulares und flexibles Verfahren zur Code-Verifikation entwickelt, das die Möglichkeit bietet, Black-Box-Codes zu testen. Das Code-Verifikationsverfahren konzentriert sich auf die Konsistenz der Code-Implementierung und die Konvergenz der Feldvariablen. Das Verfahren zur Codeverifizierung besteht aus analytischen Benchmarks, entweder exakt oder hergestellt, mit zunehmender Komplexität, um die Implementierung jedes Terms in der Navier-Stokes-Gleichung zu testen. Zweitens verfügt das Rahmenwerk zur Glaubwürdigkeitsbewertung über einen Leitfaden zur Quantifizierung von Diskretisierungsfehlern/Unsicherheiten. Genauer gesagt, werden Richtlinien für die Verifizierung der Lösung definiert. Die Schätzung des Diskretisierungsfehlers/der Unsicherheit basiert auf dem Richardson-Extrapolationsansatz. Ein lösungsverzerrter Unsicherheitsschätzer wird verwendet, um die Verwendung unstrukturierter Gitter, ungleichmäßiger Verfeinerung und nicht asymptotischer Lösungen zu berücksichtigen. Der neu entwickelte Rahmen hat eine neue Definition für die Messung der Gittergröße, die Behandlung von Simulationsdaten mit anomalem Verhalten und für die Definition des Sicherheitsfaktors bei der Unsicherheitsquantifizierung des Diskretisierungsfehlers. Die Bewertungsmethodik eignet sich sowohl für gut als auch für schlecht verhaltene Simulationsfolgen. Die Leistungsfähigkeit der Bewertungsmethodik wird mit einem Blick auf die Validierung mit experimentellen Daten überprüft. Abschließend kann festgestellt werden, dass die entwickelte Verifikationsmethodik hoch qualifiziert ist, um die Qualität von CWE-Simulationen zu beurteilen. Darüber hinaus macht die Allgemeingültigkeit und Modularität des Rahmens es für jede Softwareumgebung unabhängig vom Diskretisierungsschema anwendbar. Folglich fördert die Methodik weitere Forschungen zur Identifizierung der Zuverlässigkeit von CWE-Simulationen

Ethiopian Dam Optimum Hydraulic Operating Conditions to Reduce Unfavorable Impacts on Downstream Countries

As noted by several researchers, the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile River is expected to have unfavorable consequences for downstream countries like Egypt and Sudan. To limit GERD's negative effects on downstream countries, its operation should be secure, and its upstream water level should be ideal. However, none of the studies carried out the ideal operating scenarios from the perspective of controlling the number of gate openings. Accordingly, this study evaluates the optimal operating scenarios of the GERD and its impact on downstream countries by adopting a mathematical model to analyze the number of gates that can be opened and the depth of opening during different filling years. The paper also presents an environmental impact assessment of some GERD significant factors during construction, filling, and operation, with the goal of developing a mitigation strategy. The results showed that opening 5 gates at 4.56 m over a 10-year filling period would be the safest, most accepted, and most advantageous for Ethiopia and downstream countries. Moreover, creating a water-saving management plan in Egypt to overcome GERD's negative impacts would cost 877 billion Egyptian pounds. Doi: 10.28991/CEJ-2022-08-09-011 Full Text: PD

STR-849: FROM EXPERIMENTAL WIND TUNNEL TO WIND-STRUCTURE INTERACTION SIMULATIONS OF A SHELL STRUCTURE

This paper studies the transition from downscaled wind tunnel testing to prototype scale numerical simulations. The study is performed using OpenFOAM as fluid solver, EMPIRE as coupling tool, and Carat++ as the structure solver. The current work aims at finding sufficient settings for wind-structure interaction simulations. Also, the efficiency of the software chain to simulate natural wind flow is approved. For this purpose, different flow conditions such as uniform, atmospheric boundary layer (ABL), and flow behind a cube (structure is positioned in the wake region behind a cube) are simulated. These complicated, unsteady, and recirculating flows are simulated to study the aeroelastic effects on light weight shell structures. Wind-structure interaction simulations are performed where the dynamics of the structure play a crucial role in the wind effects. An Aluminum shell structure was tested in the wind tunnel to have an experimental benchmark for aeroelasticity. Throughout spectral analysis of structure vibrations and statistical evaluation of forces, the modeling approach shows a very good agreement with the experimental results. Finally, scaling issues represent a great challenge to wind tunnel testing especially when it comes to light-weight structures. While significantly, numerical simulations are shown to be an efficient tool for the prediction of wind loading on structure under different wind conditions

An integrated framework for the reliability and validity assessment of numerical wind engineering simulations

Towards complex architecture and light-weight structures, conventional wind load estimation techniques fail. Hence, Computational Wind Engineering (CWE) plays a crucial role. CWE can be a very helpful tool in all design stages from schematic to detailed design stage. With the current advances in CWE, numerical wind tunnel simulations has a great potential towards improving the structural design quality through better understanding of the wind loads on structures. However, the quality of simulations is still questionable. Despite the increasing attention given to the quantification of error and uncertainty in CFD, the techniques that have been developed for general fluid engineering problems to assess the quality of CFD simulations are still marginally used in CWE (Jrg Franke, 2010). This paper is part of a project aiming at defining a framework to assess the predictive capability of wind load computation using CWE with error estimation. The framework consists of three main work packages: Code Verification, Solution Verification, and Validation. Overall, the generic definition of the framework is stepwise exemplified with the open-source code KRATOSMultiphysics. In this paper, Code Verification is the main concern. The Method of Manufactured solutions is used to verify the Variational Multiscale (VMS) element in KratosCFD incompressible Navier-Stokes solver. TaylorGreen vortex is the basis for the verification test. The Taylor-Green vortex is a wellstudied test problem for large eddy simulation (LES) subgrid scale models. Moreover, Taylor-Green vortex is modified to have more extensive testing for the code. Finally, a second order convergence rate is observed which verifies the tested code functionality, then numerical errors are to be quantified

Continuous positive airway pressure ventilation during whole lung lavage for treatment of alveolar proteinosis -A case report and review of literature

Pulmonary alveolar proteinosis (PAP) is a rare disease that affects young population usually in the age group of 20-40 years, characterized by the deposition of lipoproteinacious material in the alveoli secondary to abnormal processing of surfactant by macrophages. We report a case of a 15-year-old female who had history of cough with sputum for 3 days along with fever. She was seen in another hospital and was treated as a case of pneumonia where she received antibiotic but with no improvement. Computerized tomography (CT) chest showed diffuse interlobular septal thickening in the background of ground glass opacity giving a picture of crazy paving pattern which was consistent with the diagnosis of PAP. The patient was scheduled to undergo, first right-sided whole lung lavage (WLL) under general anesthesia. Endobronchial intubation using left sided 37 Fr double lumen tube. Continuous positive airway pressure (CPAP) as described in our previously published report was connected to the right lumen of the endobronchial tube. CPAP ventilation was used during the suctioning of lavage fluid phase in order to improve oxygenation. WLL was done using 5 L of warm heparinized saline (500 i.u/litre). The same procedure was repeated on the left side using 6 L of heparinized normal saline solution. In conclusion, anesthesia in alveolar proteinosis for patients undergoing WLL is challenging to the anesthesiologist. It requires meticulous preoperative preparation with antibiotics, mucolytics and chest physiotherapy. Also it requires careful intraoperative monitoring and proper oxygenation especially during the suctioning phase of the lavaged fluid. With this second case report of successful anesthetic management using the modified CPAP system we recommend with confidence the application of CPAP ventilation to improve oxygenation during WLL

Comparative Effects of Isokinetic Training and Virtual Reality Training on Sports Performances in University Football Players with Chronic Low Back Pain-Randomized Controlled Study

Objective. The objective of this study is to find and compare the effects of isokinetic training and virtual reality training on sports performances in university football players with chronic low back pain. Design. This is a randomized, double-blinded controlled study. Methods. The study was conducted on 45LBP participants at university hospital. First group (n = 15) received isokinetic training, second group (n = 15) received virtual reality training, and the control group (n = 15) received conventional training exercises for four weeks. Clinical (pain intensity and player wellness) and sports performance (40 m sprint, 4 × 5 m sprint, submaximal shuttle running, countermovement jump, and squat jump) scores were measured at baseline, after 4 weeks, 8 weeks, and 6 months. Results. Four weeks following training VRT group shows more significant changes in pain intensity and player wellness scores than IKT and control groups (p≤0.001). Sports performance variables (such as 40 m sprint, 4 × 5 m sprint, submaximal shuttle running, countermovement jump, and squat jump) scores also show significant improvement in VRT group than the other two groups (p≤0.001). Conclusion. Overall, our study suggests that strength training through virtual reality training protocol improves pain and sports performances than isokinetic training and other conventional trainings in university football players with chronic low back pain

A Randomized Comparative Study between High-Intensity and Low-Level Laser Therapy in the Treatment of Chronic Nonspecific Low Back Pain

Objectives. Chronic nonspecific low back pain (chronic nsLBP) is one of the most common musculoskeletal disorders leading to disabilities and physical inactivity. Laser therapy was used in chronic nsLBP treatment; however, no previous studies have assessed the impacts of high-intensity laser therapy (HILT) versus low-level laser therapy (LLLT) on chronic nsLBP. This study compared the effects of HILT versus LLLT on individuals suffering from chronic nsLBP. Methods. The study was a randomized control trial. Sixty individuals with chronic nsLBP were enrolled in this study between May and November 2019. All participants were clinically diagnosed with chronic nsLBP. They were assigned randomly into three groups, 20 in each group. The first group received a program of LLLT, the second group received a program of HILT, and the third did not receive laser therapy (control group). Pain severity, disability, lumbar mobility, and quality of life were assessed before and after 12-week intervention. Results. Both LLLT and HILT groups showed a significant improvement of the Oswestry Disability Index (ODI), visual analogue scale (VAS), lumbar range of motion (ROM), and European Quality of Life (EuroQol) scores (p>0.05), while the control group did not show significant changes (p>0.05). Comparison among the three study groups postintervention showed significant differences in the outcome measures (p>0.05), while comparison between the LLLT and HILT groups showed nonsignificant differences (p>0.05). Conclusion. There are no different influences of LLLT versus HILT on chronic nsLBP patients. Both LLLT and HILT reduce pain and disability and improve lumbar mobility and quality of life in chronic nsLBP patients