Computational Design in Mechanical Engineering Applications via CFD: Uncertainty Quantification and Optimisation

Engineering practice is nowadays inconceivable without the presence of computational tools. Within this context, Computational Fluid Dynamics (CFD) are an essential tool for fluid-based machine design, such as heat exchangers, turbines, cooling processes or aerodynamic performance of vehicles. Among the simulation capabilities of modern softwares, Reynolds-Averaged Navier Stokes (RANS) simulations are the most popular industrial approach, due to the decent computation elapsed times and accuracy for a vast range of applications. However, some engineering applications that simulate complex flows may exhibit certain discrepancies as a consequence of neglected sources of uncertainty. The effect of uncertainty can be even increased when the effect of different sources of inaccuracy are combined in the simulation. Once a reliable computational model is achieved, further designs can be explored. One advantage of CFD is that prototyping costs can be reduced by performing optimisation via simulation. This allows to obtain a large number of data at lower cost than experimental testing. Thus, such data can be further used to train Machine Learning algorithms that may improve or speed up the optimisation process. In this presentation, the aforesaid concepts will be shown. Different examples of uncertainty propagation in CFD simulations of engineering applications will be illustrated. Finally, a successful case of Machine Learning aided optimisation of a mechanical micro heat exchanger/mixer will be presented. This research is supported by the UMA18-FEDERJA-184 funding.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech Investigación subvencionada por: contrato UMA18-FEDERJA-184 y Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI - Junta de Andalucía

Two-step numerical simulation of the heat transfer from a flat plate to a swirling jet flow from rotating pipe

Purpose: Impinging jets have been widely studied and the addition of swirl has been found to be beneficial to heat transfer. Since there is no literature on RANS nor experimental data of swirling jet flows generated by a rotating pipe, this paper attempts to fill such gap by providing results on the performance of this type of design. Design/methodology/approach: Since the flow has a different behaviour at different parts of the design, the same turbulent model cannot be used for the full domain. To over-come this complexity, the simulation is split into two coupled stages. This is an alternative to use the costly Reynold Stress Model (RSM) for the rotating pipe simulation and the SST k-ω model for the impingement. Findings: To induce swirl by rotating pipes with swirl intensity ranging from 0 to 0.5 affects the velocity profiles but not noticeably the spreading angle. The heat transfer is increased with respect to a non-swirling flow only at short nozzle-to-plate distances H/D < 6, where H is the distance and D is the diameter of the pipe. For the impinging zone, the highest average heat transfer is achieved at H/D = 5 with swirl intensity S = 0.5. This is the highest swirl studied in this work. Research limitations/implications: High-fidelity simulations or experimental analysis may provide reliable data for higher swirl intensities, which is not covered in this work with RANS. Practical implications: This two-step approach and the data provided is of interest to other related investigations (e.g. using arrays of jets or other surfaces than flat plates). Originality/value: This paper is the first of its kind RANS simulation of the heat transfer from a flat plate to a swirling impinging jet flow issuing from a rotating pipe. An extensive study of these CFD simulations has been carried out with the emphasis of splitting the large domain into two parts to facilitate the use of different turbulent models and periodic boundary conditions for the flow confined in the pipe

Two-Dimensional-Based Hybrid Shape Optimisation of a 5-Element Formula 1 Race Car Front Wing under FIA Regulations

Front wings are a key element in the aerodynamic performance of Formula 1 race cars. Thus, their optimisation makes an important contribution to the performance of cars in races. However, their design is constrained by regulation, which makes it more difficult to find good designs. The present work develops a hybrid shape optimisation approach to obtain an optimal five-element airfoil front wing under the FIA regulations and 17 design parameters. A first baseline design is obtained by parametric optimisation, on which the adjoint method is applied for shape optimisation via Mesh Morphing with Radial Basis Functions. The optimal front wing candidate obtained outperforms the parametric baseline up to a 25% at certain local positions. This shows that the proposed and tested hybrid approach can be a very efficient alternative. Although a direct 3D optimisation approach could be developed, the computational costs would be dramatically increased (possibly unaffordable for such a complex five-element front wing realistic shape with 17 design parameters and regulatory constraints). Thus, the present approach is of strong interest if the computational budget is low and/or a fast new front wing design is desired, which is a frequent scenario in Formula 1 race car design.The authors want to acknowledge the financial support from the Ramón y Cajal 2021 Excellence Research Grant action from the Spanish Ministry of Science and Innovation (FSE/AGENCIA ESTATAL DE INVESTIGACIÓN), the UMA18-FEDERJA-184 grant, and the Andalusian Research, Development and Innovation Plan (PAIDI—Junta de Andalucia) fundings. Partial funding for open access charge: Universidad de Málag

Diseño de un pabellón semiabierto para usos docentes en el Campus de Teatinos (Málaga)

Los espacios exteriores raramente se utilizan para desarrollar actividades docentes, ya que resulta difícil asegurar las condiciones requeridas de confort térmico, lumínico y acústico. Estos problemas pueden mitigarse en gran medida concibiendo una estructura arquitectónica semi-confinada, que facilite el control del ambiente interior pero sin romper totalmente la conexión con el entorno. Siguiendo con esta idea, en este artículo se discuten las características de un “aula exterior” diseñada por un grupo de profesores y alumnos de la Universidad de Málaga. La estructura del aula se ha diseñado utilizando técnicas de arquitectura paramétrica, buscando que la forma siga al clima. Para conseguirlo, se incorporan elementos de sombra, protección contra el viento, ventilación natural, aislamiento e inercia térmica, producción fotovoltaica, un sistema radiante en paredes y suelo, y un sistema de sensorización avanzado. El sistema radiante se utiliza para mejorar la sensación térmica de los ocupantes cuando sea necesario, y se alimenta mediante una bomba de calor accionada eléctricamente. La producción fotovoltaica, complementada con conexión a red (sin inyección), se destina a satisfacer las necesidades eléctricas del pabellón: iluminación, sensores, bomba de calor y sistema hidráulico. En el artículo se discute la incorporación de estos elementos en la estructura y se cuantifica su comportamiento térmico mediante simulaciones por ordenador.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Machine Learning-Aided Design Optimisation(MLADO) in Vortex Shedding-Based Engineering Applications

Computational design is a key part in most engineering applications, thanks to the possibility to create new designs in a safer, quicker and reliable environment. The recent developments in engineering are also guiding the classical design life cycle to a more sophisticated frameworks, such as the implementation of Machine Learning methods to support the design process. This work shows the potential of using the namely Machine Learning-Aided Design Optimisation framework to optimise vortex-shedding based applications, and it is applied as example to a vortex shedding aerodynamic-based design extendable to other applications. This framework consisted of using a predictive model to discard useless computations and speed up the efficient construction of surrogate models. The method is applied to the optimisation of a mechanical vortex shedding-based passive mixer achieving a successful design in terms of minimisation of pressure drop and maximisation of mixing efficiency

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P &lt; 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field