Improving the forecasting of oil spills from underwater sources

При прогнозировании процессов всплытия нефти от подводных источников в условиях открытой воды существует необходимость получения информации в ускоренном временном режиме для эффективного планирования защитных мероприятий в целях минимизации вреда окружающей среде, что возможно достичь совместным применением методов вычислительной гидродинамики и математической статистики. В работе приведено описание усовершенствованной математической модели всплытия нефтепродуктов от подводных источников. В целях повышения функциональности ранее созданной авторами системы уравнений связи для оценки параметров области возможного всплытия нефти увеличен диапазон изменения одного из ключевых независимых факторов – глубина водоема. В качестве факторов рассматривались: время всплытия, площадь области всплытия нефти, скорость глубинных течений, объем и тип разлитого нефтепродукта, глубина водоема. Новая регрессионная модель прогноза подводного движения разлива нефти обеспечивает прогнозирование распространения нефтяного загрязнения на морских акваториях. Представлены результаты оценки качества разработанной регрессионной модели прогноза подводного движения разлива нефти при всплытии, которая позволяет выполнять оценку параметров области всплытия нефти с одновременным учетом процессов растекания и перемещения под действием глубинных течений. Разработана методика прогноза подводного движения разлива нефти и алгоритм ее практической реализации. Определены структуры входных и выходных данных алгоритма. Приведен пример практического применения модели в Балтийском море. When predicting the processes of oil surfacing from underwater sources in open water conditions, there is a need to obtain information in an accelerated time mode for effective planning of protective measures in order to minimize environmental harm, which can be achieved by the combined application of computational fluid dynamics and mathematical statistics. The paper describes an improved mathematical model for the emergence of oil products from underwater sources. In order to increase the functionality of the system of constraint equations previously created by the authors for assessing the parameters of the area of possible oil flooding, the range of variation of one of the key independent factors, the depth of the reservoir, has been increased. The factors considered were the ascent time, the area of the oil surfacing, the speed of deep currents, the volume and type of spilled oil product, and the depth of the reservoir. The new regression model for predicting the underwater movement of an oil spill provides for predicting the spread of oil pollution in offshore areas. The paper presents the results of assessing the quality of the developed regression model for predicting the underwater movement of an oil spill during ascent, which makes it possible to assess the parameters of the area of oil ascending while taking into account the processes of spreading and movement under the influence of deep currents. A method for predicting the underwater movement of an oil spill and an algorithm for its practical implementation have been developed. The structures of the input and output data of the algorithm are determined. An example of the practical application of the model in the Baltic Sea is given.

The Analysis of Biomimetic Caudal Fin Propulsion Mechanism with CFD

In nature, fish not only have extraordinary ability of underwater movement but also have high mobility and flexibility. The low energy consumption and high efficiency of fish propulsive method provide a new idea for the research of bionic underwater robot and bionic propulsive technology. In this paper, the swordfish was taken as the research object, and the mechanism of the caudal fin propulsion was preliminarily explored by analyzing the flow field structure generated by the swing of caudal fin. Subsequently, the influence of the phase difference of the heaving and pitching movement, the swing amplitude of caudal fin, and Strouhal number (St number) on the propulsion performance of fish was discussed. The results demonstrated that the fish can obtain a greater propulsion force by optimizing the motion parameters of the caudal fin in a certain range. Lastly, through the mathematical model analysis of the tail of the swordfish, the producing propulsive force principle of the caudal fin and the caudal peduncle was obtained. Hence, the proposed method provided a theoretical basis for the design of a high-efficiency bionic propulsion system.

Одиночное и совместное движение суперкавитирующих ударников в сверхзвуковом режиме в воде

The research considers features of the underwater movement of single and two supercavitating strikers when simultaneous penetration into the water at speeds exceeding of sound speed. Conditions which provide non-destructive penetration into the water of strikers and their stable movement along an aiming trajectory at the transonic speed range has been developed. A stable cooperative movement of two strikers at the supersonic speed has been realized.

Kinematic Analysis of the Kick Start Underwater Phase of Young Male Swimmers

Introduction: The introduction of a starting block with an adjustable and slanted footrest has caused the development of a new starting technique - the Kick Start. Therefore, research on swim start seems necessary, particularly concerning the Kick Start underwater phase. Aim: The study aim was to characterise the underwater phase of the Kick Start among young, male, competitive swimmers. Basic procedures. The study included 32 male, youth, competitive swimmers (mean age=16.61 years, height=1.80 m, body mass=72.47 kg, FINA Points=617). Participants executed three freestyle Kick Starts recorded using an underwater high-speed camera. Videos were kinematically analysed using the Skill Spector programme. Then, k-means clustering was applied. Results. Participants were classified into three clusters. Cluster FT (“flat trajectory”) comprised swimmers with a ”flat” course of underwater movement - low value of the angle of water attack (KA=0.92o), maximum depth of the head (hmax=0.85 m), distance (dmax=0.71 m), and time to maximum depth of the head (tmax=0.51 s). Group MT (“moderate trajectory”) had moderate values of the above-mentioned parameters (KA=10.27o, hmax=0.93 m, dmax=1.03 m, tmax=0.60 s), while Cluster DT (“deep trajectory”) achieved the highest values (KA=15.74o, hmax=1.05 m, dmax=1.38 m, tmax=0.73 s). The time to reach 15 m in Cluster FT was about 0.3 s slower than in Group MT and DT, although this dissimilarity was not significant. Conclusions. The course of underwater movement is mostly affected by the angle at which swimmers submerge. There is no “ideal” way to perform the underwater phase, however, it should not be executed too close to the water surface.

THE INFLUENCE OF APNEA IN PHYSIOLOGICAL RESPONSES OF FEMALE SWIMMERS

The purpose of this study was to investigate the differences in maximum concentration of lactic acid in the blood, heart rate and performance time on the test of 4x50m freestyle swimming on a sample of two protocols: a) one breath every 3 strokes and b) 14-15m of every 50m were swum with underwater movement of the feet without breathing and a rest with one breath every 3 strokes (apnea). The sample consisted of 15 female swimmers of the competitive level aged: 15.0 ± 1.0 years. Their basic style was the freestyle. To determine the maximum blood lactate concentration, capillary blood samples were taken in the 3rd, 5th, 7th minute and analyzed by the automatic analyzer Scout Lactate Germany. We also measured the heart rate immediately after each swimming protocol. The ANOVA showed that there were no statistically significant differences between the two protocols. Maximum lactate concentration in the protocol with apnea was 10.02 ± 3.05mmol / L and without apnea 8.9 ± 3.5mmol / L. Heart rate was 186 ± 6 and 186 ± 7 b/min respectively, and performance time 140.04 ± 8.13 and 138.73 ± 8.01sec in swimmers aged 14-16. Swimming apnea needs to be studied in a larger age sample with more variables to ascertain the effects on sprint swimming.

The Structure Design of the Mini Underwater Robot

A kind of mini underwater robot is introduced in this artical. Aim at the situation of shallow water area(5m~30m)，we analyzed and designed the structure of the whole robot pertinently, and calculated the underwater movement resistance, which thereby could give theoretical support on the choice of thrusters. The robot detects the underwater situation effectively by high definition camera that installed in the front of the robot, and achieves lifting and turning movement though 3 propellers. The manipulator installed in above of the robot could grab underwater objects effectively.

Smart-E An Autonomous Omnidirectional Underwater Robot

The survey of waterbodies or underwater installations is a challenging task. To reduce the danger for divers, Autonomous Underwater Vehicles (AUVs) can be deployed. These requires a high manoeuvrability and agility in order to provide access in hard-to-reach areas. Smart-E is an omnidirectional AUV designed and developed at the Institute of Computer Engineering of the University of Luebeck. The drive is realized by the minimal configuration of three thrusters that are arranged at 120º to each other. To achieve omnidirectional movement in the 3D space, each motor pivots through 180º around its radial axis with the aid of a servo motor. This leads to a manoeuvrability of six degrees of freedom (DOF). Smart-E is equipped with various sensors like a pressure and temperature sensor, a 360º scanning sonar, an IMU-AHRS system and a tilt camera unit at the bottom. Besides the autonomous behaviors, the main challenge is to control all six DOF of the AUV to achieve a smooth and controllable omnidirectional underwater movement even in rough environments.

A Determination of an Abrupt Motion of the Sea Bottom by Using Snapshot Data of Water Waves

This paper presents an inverse problem and its solution procedure, which are aimed at identifying a sudden underwater movement of the sea bottom. The identification is mathematically shown to work with a known snapshot data of generated water wave configurations. It is also proved that the problem has a unique solution. However, the inverse problem is involved in an integral equation of the first kind, resulting in an ill-posed problem in the sense of stability. That is, the problem lacks solution stability properties. To overcome the difficulty of solution instability, in this paper, a stabilization technique, called regularization, is incorporated in the present solution procedure for the identification of the sea bottom movement. A numerical experiment is presented to demonstrate that the proposed (numerical) solution procedure operates.