Flow characterisation in an exhaust manifold of a single-cylinder internal combustion engine (ICE)

This paper presents an investigation of flow characteristic inside the exhaust manifold that were designed with different bending angle (BA), bending radius (BR) and pipe diameter (Dp ). Five exhaust manifold models were developed and analysed by the computational fluid dynamic (CFD) method. Accordingly, the pressure distribution, velocity streamline and backpressure values were observed. The simulation results showed a different flow pattern for all five models, indicating the manifold design affect the flow characteristic inside the exhaust system. The results demonstrated that the pressure distribution inside the exhaust manifold is influencing its velocity streamline pattern, that directly effecting the outlet velocity of the exhaust gas. From this work, a small bending angle with a short straight pipe has led to a smoother exhaust flow and even exhaust velocity across the model. The results obtained from the simulation can be used as a guide to improve the understanding of the flow behaviour in the manifolds and might be used to improve the manifold design.

Flood forecasting with machine learning models in an operational framework

Google’s operational flood forecasting system was developed to provide accurate real-time flood warnings to agencies and the public, with a focus on riverine floods in large, gauged rivers. It became operational in 2018 and has since expanded geographically. This forecasting system consists of four subsystems: data validation, stage forecasting, inundation modeling, and alert distribution. Machine learning is used for two of the subsystems. Stage forecasting is modeled with the Long Short-Term Memory (LSTM) networks and the Linear models. Flood inundation is computed with the Thresholding and the Manifold models, where the former computes inundation extent and the latter computes both inundation extent and depth. The Manifold model, presented here for the first time, provides a machine-learning alternative to hydraulic modeling of flood inundation. When evaluated on historical data, all models achieve sufficiently high-performance metrics for operational use. The LSTM showed higher skills than the Linear model, while the Thresholding and Manifold models achieved similar performance metrics for modeling inundation extent. During the 2021 monsoon season, the flood warning system was operational in India and Bangladesh, covering flood-prone regions around rivers with a total area of 287,000 km2, home to more than 350M people. More than 100M flood alerts were sent to affected populations, to relevant authorities, and to emergency organizations. Current and future work on the system includes extending coverage to additional flood-prone locations, as well as improving modeling capabilities and accuracy.

Maneuverability Towing Tank Experiments With Manifold Models: Part I — Static Tests

This work is the Part I of a two-part work, where the maneuverability of three manifold geometries was investigated by Towing Tank tests at the Institute for Technological Research, in order to verify the influence of geometrical simplifications and modifications. In this work is presented a comparison between the forces and moments measured in static drift tests, considering a pitch orientation ranging from 0 to 360 degrees, and the static hydrodynamic derivatives in a reference orientation. In the Part II, the investigations were complemented by the results of dynamic tests. The manifold models were constructed in a 1:13 scale. The first model was a geometrically simplified version of the prototype, composed of two simple blocks; the second one was constructed with almost all the prototype geometric details; the last one used the second model with a plate installed on its top. The tests results indicate that the geometrical simplification of manifold models did not have a significant influence on the maneuvering coefficients, in contrast to the addition of the top plate, which significantly changed the maneuvering capabilities of the model. The study presented in both papers will be used to form a data base for numerical simulation studies for manifolds installation.

Maneuverability Towing Tank Experiments With Manifold Models: Part II — PMM Oscillation Tests

This work is the Part II of a two-part work, where the influence of geometrical simplifications and modifications in the maneuverability of a manifold were investigated by three 1:13 scaled models in a towing tank. In this work is presented the adopted methods that were used to obtain the hydrodynamic derivatives from forced oscillations motions in a towing tank using a planar-motion-mechanism. In the part I was presented the static drift tests, which were used to complement the tests presented in this paper. The maneuvering hydrodynamic derivatives are obtained by a two part analysis. First, the measured forces, moments and motions time series signals are filtered and decomposed in harmonic functions. Second, regression analysis techniques are applied to the amplitude of these harmonic functions in order to estimate the hydrodynamic derivatives. The results have showed that the simplification of the manifold geometry has a low influence in the hydrodynamic derivatives in contrast to the installation of a larger plate, which modified the manifold maneuverability significantly. The presented investigation in both papers will be used to form a data base for numerical simulation studies for manifolds installation.

Panalesis: towards global synthetic palaeogeographies using integration and coupling of manifold models

Palaeogeographic reconstructions have been proposed for years. The technique employed, however, is more or less always the same: it consists of determining the palaeoenvironment at the local scale and extending it to the regional scale. Such work is carried out in a maximum number of locations all over the planet and the global palaeogeography is the result of interpolation of those reconstructions. Advances in palaeogeography can be made via an alternative way, which consists of integrating and then coupling various global models. It results in the proposal of synthetic palaeogeographies that can be compareda posteriorito local or regional data. The advantage is twofold: (1) the view is really global and it avoids gaps (in particular in the oceanic realm) in the reconstructions, and it is very much less focused on the coastline; (2) it takes advantages from almost all the fields of geosciences, so that reconstructions can be constrained from a large variety of data. The two techniques – the ‘classic’ and the ‘alternative’ – are not contradictory but complementary, and it is desirable that one feeds the other and the study of palaeogeography be revived.