arXiv subjects

Chongwei Zhang

Publications and source records attributed to Chongwei Zhang.

4 recordsLinked to original sources

arXiv2026

A black-box-model-enhanced interaction method for water-wave scattering by large group of arbitrary-shaped ice floes in Arctic route planning

This study develops an enhanced interaction (EI) method for efficient prediction of the water-wave field among a large group of ice floes in Arctic route planning. A novel black-box model, termed the wave component detection (WCD) method, is proposed for constructing the diffraction transfer matrix (DTM) within the framework of interaction theory. The DTM, which is conventionally mathematically intractable for three-dimensional ice floes with arbitrarily complex geometry, can now be determined using this readily implementable and universally applicable approach. Without loss of generality, four ice-floe shapes are taken as example models to demonstrate the capability of the EI method. Operation rules are recommended for the practical implementation of the EI method. The error range of the EI method is identified in scenarios with multiple ice floes of different sizes and distances.The super-high efficiency of the EI method is demonstrated in cases involving an ultra-large group of ice floes. It takes less than 1.5 hours to calculate wave amplitudes at 160,000 locations in the wave field of 1,800 ice floes (based on 1,440,000 boundary elements) on an ordinary personal computer with a 2017-released CPU. Based on the wave field predicted by the EI method, users can take advantage of the wave-sheltering effect of the ice floes to optimize routes. For demonstration, the dynamic programming strategy is used to recommend optimized navigation routes among 1561 ice floes of mixed shapes. The average wave amplitude the ship encounters can be reduced to about half of the incident wave amplitude.

physics.ao-ph↗

arXiv2025

Coupled hydro-aero-turbo dynamics of liquid-tank system for wave energy harvesting: Numerical modellings and scaled prototype tests

An integrated numerical model is proposed for the first time to explore the coupled hydro-aero-turbo dynamics of wave-energy-harvesting (WEH) liquid tanks. A scaled prototype of the WEH liquid tank with an impulse air turbine system is made to experimentally validate the numerical model.Multi-layered impulse air turbine systems (MLATS) are creatively introduced into the liquid-tank system. The inherent mechanisms of the coupled hydro-aero-turbo dynamics of the WEH liquid tank with different turbine properties are systematically investigated.Compared with the experimental data, the numerical model can accurately reproduce the rotor speed, liquid motion, and air pressure of the WEH liquid tank. Upon analysing mechanical parameters of the turbine rotor, it is found that the rotor's moment of inertia mainly affects the rotor speed's variation range, while the damping coefficient significantly influences the averaged rotor speed. The optimal power take-off damping for the WEH liquid tank is identified. Considering the efficiency performances of three MLATSs, improving Turbine-L1 to Turbine-L2 or Turbine-L3 can increase the averaged power output by about 25% or 40%, respectively.Increasing the tank breadth can effectively boost the power output in a nonlinear way.Under the considered excitation conditions, if the tank breadth is doubled, the maximum averaged power output can be increased by around four times. Through a series of failure tests, Turbine-L3 shows greater reliability in extreme conditions compared to a conventional single-rotor turbine. Even if the most important rotor of Turbine-L3 fails to work, the maximum loss of the averaged power output is only 44%. The present WEH liquid with Turbine - L3 shows improved efficiency and reliability compared to the conventional liquid-tank system with a single-rotor turbine.

physics.flu-dyn↗

arXiv2024

Fundamental bounds on many-body spin cluster intensities

Multiple-quantum coherence (MQC) spectroscopy is a powerful technique for probing spin clusters, offering insights into diverse materials and quantum many-body systems. However, prior experiments have revealed a rapid decay in MQC intensities as the coherence order increases, restricting observable cluster sizes to the square root of the total system size. In this work, we establish fundamental bounds on observable MQC intensities in the thermodynamic limit outside the weak polarisation limit. We identify a sharp transition point in the observable MQC intensities as the coherence order grows. This transition points fragments the state space into two components consisting of observable and unobservable spin clusters. Notably, we find that this transition point is directly proportional to the size $N$ and polarization $p$ of the system, suggesting that the aforementioned square root limitation can be overcome through hyperpolarization techniques. Our results provide important experimental guidelines for the observation of large spin cluster phenomena.

quant-ph↗

arXiv2021

Sloshing dynamics of liquid tank with built-in buoys for wave energy harvesting

This paper proposes a novel design of liquid tank with built-in buoys for wave energy harvesting, named the 'sloshing wave energy converter (S-WEC)'. When the tank is oscillated by external loads (such as ocean waves), internal liquid sloshing is activated, and the mechanical energy of sloshing waves can be absorbed by the power take-off (PTO) system attached to these buoys. A fully-nonlinear numerical model is established based on the boundary element method for a systematic investigation on dynamic properties of the proposed S-WEC. A motion decoupling algorithm based on auxiliary functions is developed to solve the nonlinear interaction of sloshing waves and floating buoys in the tank. An artificial damping model is introduced to reflect viscous effects of the sloshing liquid. Physical experiments are carried out on a scaled S-WEC model to validate the mathematical and numerical methodologies. Natural frequencies of the S-WEC system are first investigated through spectrum analyses on motion histories of the buoy and sloshing liquid. The viscous damping strength is identified through comparisons with experimental measurements. Effects of the PTO damping on power generation characteristics of S-WEC is further explored. An optimal PTO damping can be found for each excitation frequency, leading to the maximisation of both the power generation and conversion efficiency of the buoy. To determine a constant PTO damping for engineering design, a practical approach based on diagram analyses is proposed. Effects of the buoy's geometry on power generation characteristics of the S-WEC are also investigated. In engineering practice, the present design of S-WEC can be a promising technical solution of ocean wave energy harvesting, based on its comprehensive advantages on survivability enhancement, metal corrosion or fouling organism inhibition, power generation stability and efficiency, and so on.

physics.flu-dyn↗