Zhengzhi Deng

Zhejiang University | ZJU · Department of Ocean Science and Engineering

In this paper, an example of a symbiotic combination of marine structures is studied. The base hydrodynamic performance of a traditional offshore oscillating water column (OWC) device is compared against the case in which it is constructed over a submerged breakwater. Numerical simulations are performed with the open source package OpenFOAM and the...

An effective urban drainage system (UDS) is crucial for solving urban flooding problems, motivating plenty of studies to design, build and rehabilitate UDSs. However, the existing design and analysis methods usually assume a uniformly spatial distribution of rainfall intensity throughout an urban catchment, while there is an observably spatial vari...

The topic focusing on dual-chamber Oscillating Water Column (OWC) system is still in its infancy. To improve energy extraction within a wider wave frequency regime, the concept of a dual-chamber OWC device with pitching front and mid lip-walls simultaneously is proposed. Its performance in wave energy capturing is analytical investigated based on p...

The performance of a heaving oscillating water column (OWC) device restrained by a spring-damper system is explored based on linear wave theory. The matching conditions along the common interfaces are employed, and the power take-off model and heaving motion equation are incorporated into the solution procedure. The device, allowed fully-free heavi...

The concept of a dual-chamber oscillating water column (OWC) device consisting of a pitching mid-wall (restrained by an angle spring stiffness) is proposed and corresponding theoretical model is established under the framework of potential flow theory. By employing the matched eigenfunction method along the common interfaces in terms of the velocit...

Traditional oscillating water column (OWC) devices are mostly fixed with almost no components allowed to move. To complement the research of OWC consisting of moving components, the capability in extracting wave energy for a device with a surging front and back lip-wall restricted by different spring stiffness values is investigated. A theoretical...

A bottom-seated oscillating water column (OWC) device with a front lip-wall which is allowed to oscillate in a pitching mode is explored under the framework of potential flow theory. By utilizing the matched eigenfunction method and employing the continuity conditions along the adjacent common interfaces, the theoretical model can be transformed in...

To share the construction and maintenance cost, an asymmetric oscillating water column (OWC) device integrated with a pile-fixed box-typed offshore breakwater is considered experimentally and numerically. A fully nonlinear numerical wave tank is established and validated with the open source solver OpenFOAM. The effects of the width and draft of re...

For the sake of extracting wave energy over a broader range of wave frequencies, dual-chamber OWC devices are more beneficial than the single-chamber one. In this paper, the concept of a dual-chamber OWC device composed by a pitching front lip-wall is proposed and by utilizing the matched eigenfunction method along the adjacent interfaces, present...

To give high performance over a broader wave frequency range and enable the multipurpose utilization of marine structures, an asymmetric offshore-stationary oscillating water column device with an outstretched bottom plate is considered theoretically. Through solving boundary value problems by means of the matched eigenfunction expansion method, th...

To improve the current understanding of the reduction of tsunami-like solitary wave runup by the pile breakwater on a sloping beach, we developed a 3D numerical wave tank based on the CFD tool OpenFOAM® in this study. The Navier-Stokes equations were applied to solve the two-phase incompressible flow, combined with an LES model to solve the turbule...

Based on the open source package OpenFOAM and the associated toolbox waves2Foam, the hydrodynamic performance of a dual-OWC system consisting of one on-shore and one offshore-stationary OWC devices is numerically investigated. The classical free surface capture method, volume of fluid (VOF) is utilized under the excitation of regular waves. The eff...

As an example of multipurpose utilization of marine structures, the hydrodynamic performance of an offshore-stationary Oscillating Water Column (OWC) device with an immersed horizontal bottom plate was investigated through both experimental tests and numerical simulations. Based on the open source package OpenFOAM and toolbox waves2Foam, the numeri...

Based on the open source package OpenFOAM and the associated toolbox waves2Foam, the hydrodynamic performance of a dual-OWC system consisting of one onshore and one offshore-stationary OWC devices is numerically investigated. The classical free surface capture method, volume of fluid (VOF) is utilized under the excitation of regular waves. The effe...

To evaluate the trapped wave energy and energy loss, the problem of wave scattering by twin fixed vertical surface-piercing plates over a stepped bottom is numerically simulated using the open source package OpenFOAM and the associated toolbox waves2Foam. The volume of fluid (VOF) method was employed to capture the free surface in the time domain....

Many low-lying tropical and subtropical reef-fringed coasts are vulnerable to inundation during tsunami events. Hence accurate prediction of tsunami wave transformation and run-up over such reefs is a primary concern in the coastal management of hazard mitigation. To overcome the deficiencies of using depth-integrated models in modeling tsunami-lik...

With the aim of broadening the wave-frequency bandwidth of high-efficiency, a small-scaled dual oscillating-water-column (OWC) system consisting of two heave-only and onshore units was numerically investigated by a well-validated computational fluid dynamics (CFD) model. Based on the popular open source package OpenFOAM, the volume of fluid (VOF) m...

10 With the aim of broadening the wave-frequency bandwidth of high-performance, an asymmetric 11 offshore-stationary oscillating water column device mounted over a submerged bottom-plate is 12 considered theoretically. The matched eigenfunction expansion method is employed to solve the 13 boundary value problem. The effects of the geometric paramet...

In this paper an example of a symbiotic combination of marine structures is studied. The base hydrodynamic performance of a traditional offshore oscillating water column (OWC) device is compared against the case in which it is constructed over a submerged breakwater. Numerical simulations are performed with the open source package OpenFOAM and the...

With the aim of broadening the wave-frequency bandwidth of high-efficiency, a small-scaled dual oscillating-water-column (OWC) system consisting of two heaving-only and onshore units is numerically investigated by a well-validated computational fluid dynamics (CFD) model. Based on the popular open source package OpenFOAM, the volume of fluid (VOF)...

In exploring the hydrodynamic properties of T-type open-type breakwaters，the matched eigenfunction expansion method was used to determine the flow field under the action of linear waves，wave loads，and reflection and transmission coefficients． Aiming at the singularity behavior of fluid motion close to the sharp corner of structure，specific orthogon...

To evaluate the trapped wave energy and energy loss, the problem of wave scattering by twin fixed vertical surface-piercing plates over a stepped bottom is numerically simulated using the open source package OpenFOAM and the associated toolbox waves2Foam. The volume of fluid (VOF) method was employed to capture the free surface in the time domain....

Recent field studies have increasingly recognized the importance of tides in dominating the coral reef hydrodynamics. Aside from the tidal level, it is also important to evaluate the effect of tidal current on wave breaking over coral reefs. In this study, a series of laboratory experiments were performed in a wave-current flume in the presence of...

The boundary value problem of the interaction between the small amplitude wave and the offshore oscillating water column (OWC) wave energy devices was solved by means of the matched eigenfunction expansion method based on the potential flow theory. A two-dimensional fully nonlinear wave-OWC numerical model was established by employing the FLUENT so...

The hydrodynamic performance of regular wave-two vertical plates-topography coupled system, comprised by two vertical penetrating plates mounted over a stepped bottom (submerged breakwater) with different dimensions, were analyzed by the use of the toolbox waves2Foam based on the open source software OpenFOAM. The effects of the gap between the two...

Many low-lying tropical and sub-tropical reef-fringed coasts are vulnerable to inundation during tsunami events. Hence accurate prediction of tsunami wave transformation and runup over such reefs is a primary concern in the coastal management of hazard mitigation. To overcome the deficiencies of using depth-integrated models in modeling tsunami-lik...

As an example of multipurpose utilization of marine structures, the hydrodynamic performance of an offshore-stationary Oscillating Water Column (OWC) device with an immersed horizontal bottom plate was investigated through both experimental tests and numerical simulations. Based on the open source package OpenFOAM and toolbox waves2Foam, the numeri...

Based on linear water-wave theory, this study investigated the scattering of oblique incident water waves by two unequal surface-piercing thin vertical rigid plates with stepped bottom topography. By using the matched eigenfunction expansion method and a least square approach, the analytical solutions are sought for the established boundary value p...

In exploring the hydrodynamic properties of T-type open-type breakwaters, the matched eigenfunction expansion method was used to determine the flow field under the action of linear waves, wave loads, and reflection and transmission coefficients. Aiming at the singularity behavior of fluid motion close to the sharp corner of structure, specific orth...

A near-shore oscillating water column (OWC) device with a surging front-wall, which can be conveniently mounted on various cliff-like shores or coastal structures, is proposed to improve the pneumatic efficiency of wave energy extraction. Based on linear potential theory, the interaction between ocean waves and the OWC device is solved by the match...

A two-dimensional multi-strip modelling is developed for the simulation of vortex induced vibration of a long flexible cylinder in the time domain. The turbulent model is used for flow motion, and the structural dynamic is solved with the finite element method. The flexible cylinder is simplified as two-dimensional planes based on strip theory, and...

The wave power extraction by a cylindrical oscillating water column (OWC) device with a quadratic power take-off (PTO) model was studied experimentally and theoretically. In the experiment, a scaled model OWC was tested in a wave flume, with an orifice being used to simulate a quadratic PTO mechanism. In the theoretical analysis, the quadratic PTO...

The effects of a moving gate on dam break flow experiments are numerically considered in this paper. The dam break flow process is modelled by a sudden gate release. A Constrained Interpolation Profile (CIP)-based model is employed to solve the Navier-Stokes equations with the free surface boundary condition to deal with the water-air-gate interact...

An analytical theory is developed for an oscillating water column (OWC) with a V-shaped channel to improve the pneumatic efficiency of wave energy extraction. An eigenfunction expansion method is used in a cylindrical coordinate system to investigate wave interaction with the OWC converter system. Auxiliary functions are introduced to capture the s...

An analytical theory is developed to study the effects of a coaxial tube-sector-shaped supporting structure on the conversion efficiency of a suspended, circular OWC converter. An eigen-function expansion method is employed in a cylindrical coordinate system to study wave interaction with an OWC converter in finite depth of water. Effects of the su...