Hydrodynamic Modelling of An Oscillating Wave Surge Converter Including Power Take-Off

To estimate the response of wave energy converters to different sea environments accurately is an ongoing challenge for researchers and industry, considering that there has to be a balance between guaranteeing their integrity whilst extracting the wave energy efficiently. For oscillating wave surge converters, the incident wave field is changed due to the pitching motion of the flap structure. A key component influencing this motion response is the Power Take-Off system used. Based on OpenFOAM, this paper includes the Power Take-off to establish a realistic model to simulate the operation of a three-dimensional oscillating wave surge converter by solving Reynolds Averaged Navier-Stokes equations. It examines the relationship between incident waves and the perturbed fluid field near the flap, which is of great importance when performing in arrays as neighbouring devices may influence each other. Furthermore, it investigates the influence of different control strategy systems (active and passive) in the energy extracted from regular waves related to the performance of the device. This system is estimated for each wave frequency considered and the results show the efficiency of the energy extracted from the waves is related to high amplitude pitching motions of the device in short periods of time

Simulation of the wave evolution and power capture of an oscillating wave surge converter

For oscillating wave surge converters (OWSC) the incident wave field is changed due to the movement of the flap structure. A key component influencing this motion response is the Power Take-Off (PTO) system used. This paper examines the relationship between incident waves and the perturbed fluid field near the flap using the Computational Fluid Dynamics method by using Reynolds Averaged Navier-Stokes (RANS) equations. Further, it investigates the influence of a PTO system in the energy extracted from regular waves. Whilst this wave evolution is not significant in the effective power captured by a unit device, it is of great importance when performing in arrays as neighbouring devices may influence each other

UCL OpenFOAM Course Notes 2019

The UCL OpenFOAM Course was initiated by the Department of Mechanical Engineering, totally free and registered under UCL doctoral school. It aims to popularise OpenFOAM among research students and help beginners to get through the initial painful stage dealing with the unfamiliar operation environment, also an excellent chance to exchange simulation skills and generate collaborations. In 2019, the course was held during 26-28 June, with our lecturers and 55 students attended. It was fantastic to see so many conversations getting started, and to feel that our UK/London community is getting stronger. We received very positive feedback, and more importantly, strong interests from worldwide users who wanted but could not join us in London. Thereby, this document is published online to demonstrate what we have taught. We hope this will be helpful for a wider audience. In Chapter 1-4, we present step-by-step guideline for installing/using/understanding OpenFOAM; subsequently, our Appendixes provides advanced tutorials for various purposes

Anemia infantil en poblaciones residentes en diferentes altitudes geográficas de Arequipa, Perú: factores maternos asociados

Objective: Determine the relationship between socio-demographic characteristics, knowledge, and good practices in anemic children and anemic child healthcare in Arequipa, Peru. Study design:  This is a cross-sectional survey. Participants were asked about their knowledge of childhood anemia, practices related to caring for anemic children, and adherence to treatment. Methods: This is a descriptive, transversal, relational field study. Three hundred mothers with anemic children were interviewed, from six districts of Arequipa, distributed at different geographic altitudes: medium-altitude, great-altitude, and sea level. Studied variables were related to socio-demographic factors, level of knowledge, anemic children care-related practices, and treatment adherence.  Results: 77.3% of children had mild anemia, 21.6% moderate, and 1% severe anemia. The number of children and disease severity were significantly related (p<0.05) to knowledge about anemia. Knowledge about anemia, living area, and geographic altitude were significantly correlated (p<0.05) with good practices in child anemia. Conclusion: the prevalence of anemia in the region of Arequipa is incremented by socio-economic factors, mother’s education, number of children, altitude, and geographic zone. The implementation of mother-centered educational programs by the government is necessary. In this sense, the results suggest further studies in social representations to understand, analyze and deepen the knowledge of the subject.Objetivo: Determinar la relación entre las características sociodemográficas, conocimientos y buenas prácticas en anemia infantil y la atención al niño anémico en Arequipa, Perú. Diseño del estudio: Se trata de una encuesta transversal. Se preguntó a los participantes sobre su conocimiento sobre la anemia infantil, las prácticas relacionadas con el cuidado de los niños anémicos y la adherencia al tratamiento. Métodos: Se trata de un estudio de campo, descriptivo, transversal, relacional. Se entrevistaron 300 madres con niños anémicos, de seis distritos de Arequipa, distribuidos en diferentes altitudes geográficas: mediana, gran y nivel del mar. Las variables estudiadas se relacionaron con factores sociodemográficos, nivel de conocimiento, prácticas relacionadas con el cuidado del niño anémico y adherencia al tratamiento. Resultados: El 77,3% de los niños presentaron anemia leve, el 21,6% moderada y el 1% anemia severa. El número de hijos y la gravedad de la enfermedad se relacionaron significativamente (p<0,05) con el conocimiento sobre la anemia. Los conocimientos sobre anemia, lugar de residencia y altitud geográfica se correlacionaron significativamente (p<0,05) con las buenas prácticas en anemia infantil. Conclusión: la prevalencia de anemia en la región de Arequipa se ve incrementada por factores socioeconómicos, escolaridad de la madre, número de hijos, altitud y zona geográfica. Es necesaria la implementación de programas educativos centrados en la madre por parte del gobierno. En ese sentido, los resultados sugieren profundizar los estudios en representaciones sociales para comprender, analizar y profundizar  el conocimiento del tema

A Review on the Modelling of Wave-Structure Interactions Based on OpenFOAM

The modelling of wave-structure interaction (WSI) has significant applications in understanding natural processes as well as securing the safety and efficiency of marine engineering. Based on the technique of Computational Fluid Dynamics (CFD) and the open-source simulation framework - OpenFOAM, this paper provides a state-of-the-art review of WSI modelling methods. The review categorises WSI scenarios and suggests their suitable computational approaches, concerning a rigid, deformable or porous structure in regular, irregular, non-breaking or breaking waves. Extensions of WSI modelling for wave-structure-seabed interactions and various wave energy converters are also introduced. As a result, the present review aims to help understand the CFD modelling of WSI and guide the use of OpenFOAM for target WSI problems

Documenting the Recovery of Vascular Services in European Centres Following the Initial COVID-19 Pandemic Peak: Results from a Multicentre Collaborative Study

Objective: To document the recovery of vascular services in Europe following the first COVID-19 pandemic peak. Methods: An online structured vascular service survey with repeated data entry between 23 March and 9 August 2020 was carried out. Unit level data were collected using repeated questionnaires addressing modifications to vascular services during the first peak (March – May 2020, “period 1”), and then again between May and June (“period 2”) and June and July 2020 (“period 3”). The duration of each period was similar. From 2 June, as reductions in cases began to be reported, centres were first asked if they were in a region still affected by rising cases, or if they had passed the peak of the first wave. These centres were asked additional questions about adaptations made to their standard pathways to permit elective surgery to resume. Results: The impact of the pandemic continued to be felt well after countries’ first peak was thought to have passed in 2020. Aneurysm screening had not returned to normal in 21.7% of centres. Carotid surgery was still offered on a case by case basis in 33.8% of centres, and only 52.9% of centres had returned to their normal aneurysm threshold for surgery. Half of centres (49.4%) believed their management of lower limb ischaemia continued to be negatively affected by the pandemic. Reduced operating theatre capacity continued in 45.5% of centres. Twenty per cent of responding centres documented a backlog of at least 20 aortic repairs. At least one negative swab and 14 days of isolation were the most common strategies used for permitting safe elective surgery to recommence. Conclusion: Centres reported a broad return of services approaching pre-pandemic “normal” by July 2020. Many introduced protocols to manage peri-operative COVID-19 risk. Backlogs in cases were reported for all major vascular surgeries