Investigation of the hydrodynamic impact of a planing small vessel on a water body

Рассмотрен экологический аспект использования маломерных глиссирующих судов. В статье представлен способ оценки характеристик потока, возмущённого движением глиссирующего судна. Способ основан на использовании численного метода гидродинамики. Выбраны параметры и зоны исследования потока вокруг корпуса рассмотренного судна, и разработана последовательность действий их определения. Проанализированы качественные картины изменения потока с ростом скорости глиссирующего судна с заданной геометрией, и выделены составляющие наиболее значимые составляющие. Оценены количественные характеристики возмущённого потока: вызванные скорости, расстояние от транца до точки зарождения системы волн, волновые характеристики. Оценка гидродинамического воздействия на водоём была проведена для двух притоков Волги – р.Керженец и р.Сура. Выполнено определение придонных касательных напряжений в выбранных водных объектах в их естественном и возмущённом присутствием судна состоянии. Проведено сравнение рассчитанных касательных напряжений с пороговыми значениями, что позволило оценить влияние движения маломерного судна на донный грунт. The ecological aspect of the use of small-sized planing vessels is considered. The article presents a method for assessing the characteristics of a flow disturbed by the movement of a planing vessel. The method is based on the use of the numerical method of hydrodynamics. The parameters and zones of the flow study around the hull of the vessel under consideration are selected, and a sequence of actions for their determination is developed. Qualitative patterns of flow changes with an increase in the speed of a planing vessel with a given geometry are analyzed, and the most significant components are identified. Quantitative characteristics of the perturbed flow are estimated: induced velocities, distance from the transom to the point of origin of the wave system, wave characteristics. The assessment of the hydrodynamic impact on the reservoir was carried out for two tributaries of the Volga - the Kerzhenets River and the Sura River. The determination of bottom tangential stresses in selected water bodies in their natural and disturbed state by the presence of the vessel was performed. The calculated tangential stresses were compared with threshold values, which made it possible to assess the impact of the movement of a small vessel on the bottom soil.

Numerical Simulation of Damage in Sandwich Composite Panels Due to Hydrodynamic Impact

The float and hull are vital parts of amphibious planes and boats, respectively, as both have to absorb hydrodynamic impact due to interaction with water. Sandwich composite panels are commonly used for such applications and other impact-absorbing structures. Unfortunately, the failure mechanism of sandwich composite panels under hydrodynamic impact is very complicated, as it may consist of composite skin failure, core failure, and non-uniform delamination. Hence, a numerical study on the damage of sandwich composite panels under hydrodynamic load is necessary. In this study, numerical simulation implementing the Coupled Eulerian-Lagrangian (CEL) method was performed to observe the damage mechanism of sandwich composite panels. The CEL method combines the Lagrangian and Eulerian frames into one model. Thus, analysis of structure deformation and fluid motion can be performed simultaneously. The result of the current numerical simulation shows a fair agreement with the experimental results in the literature, which shows that the current methodology can represent the sandwich composite panel response in real-life conditions, especially before shear core failure initiates.

Numerical model of fracture formation in a coal seam

The article discusses the recovery process of fracture system formation after hydraulic fracturing in a coal seam, based on the conducted seismic studies using modern mathematical software packages. Model concepts of the fractures system development under hydrodynamic impact on a rock mass are considered, which make it possible to assess the nature of fractures propagation.

Hydrodynamic impact and power production of tidal turbines in a storm surge barrier

To estimate the impact on energy production and environment of tidal turbines placed in the Eastern Scheldt Storm Surge Barrier a Computational Fluid Dynamics (CFD) study has been carried out on the additional head differences induced by the turbines. The CFD model focusses on a single gate opening of the Storm Surge Barrier and includes half of the adjoining gates on either side. In this 40 m wide Gate a 1.2 MW array existing of five Tocardo T2 tidal turbines has been installed as part of a demonstration project in 2015. Transient computations of the barrier with and without the turbine array were carried out for a range of quasi stationary tidal phases. The turbines are resolved in detail as rotating equipment: real-time rotation of the turbine blades (involving the displacement of the mesh nodes in an unsteady setting) is implemented, and torque and thrust for the prescribed speed of rotation is provided as output. The results for velocity, power and thrust are compared with field experiments to validate the model. Based on these computations an estimate of the effect of turbines on the discharge capacity of the storm surge barrier is given. This information will be used to parameterize the tidal turbines in the far-field hydrodynamic model of Eastern Scheldt estuary for the ultimate assessment of the effect of tidal turbines on energy production and on the environment.

Hydrodynamic Assessment of a Biofouled Wave Buoy in Coastal Zone

Accumulation of biological growth or biofouling can significantly influence the measurement accuracy of a buoy, unless it is cleaned on frequent intervals. This paper addresses the hydrodynamic impact of biofouling on met-ocean buoys moored in coastal zones. The analyses are mostly based on a Brazilian Navy buoy on the coast of Rio de Janeiro – Brazil. After only four months moored in the warm waters of the Guanabara Bay, the same buoy gained 25% in weight due to fouling, with additional important modifications on the shape and drag below the waterline. Initially, historical data measured by the buoy was analyzed to observe changes in its response over time. A motion response factor (lateral motion/vertical motion) was calculated from the data that showed a significant impact of biofouling for particular wave conditions. Next, OpenFOAM is used to perform RANS simulations for the buoy, at three different wave scenarios, in both clean and fouled condition to observe the difference in hydrodynamic response. The results indicated that the response amplitude operator varies notably for low and high-frequency cases between cleaned and fouled buoy. Our paper suggests that standard guidelines related to buoy cleaning intervals for biofouling and uncertainty applied in their measured readings may not be equal for all conditions. Buoys placed near the coast with warmer waters are more prone to biofouling and might have higher uncertainty in their measured data.