Severe slugging is an unstable multiphase flow pattern occurs in a pipeline riser with low gas and liquid flowrates. It highly undesired practical operation because of the pressure mass oscillations induced. Riser outlet choking has shown effectiveness eliminating or reducing severity slugging. This work presents experimental numerical study on elimination severe riser-induced slug by means cho...

There are huge amounts of data that describe the character of the seabed based on samplings and direct inspections made over decades. That data continues to grow rapidly and are still the richest and most detailed source of seabed information, an essential adjunct of modern remote sensed data types. One impediment to the wider use of the sample data is that it is difficult to draw area-maps (gr...

Acoustic seabed characterisation is known to make available very useful information for various marine related applications. Most existing single-beam echo sounder (SBES) classifications require ground truthing in order to have confidence in the final results and sometimes to relate labels to geological features. A statistical feature extraction approach, with an emphasis on quality control, is...

The long-term objective of this work is to develop methods for rapid assessment of seabed variability combined with detailed localized geoacoustic inversions to characterize the bottom for shallow-water environments. Consideration is given to spatial and temporal variability of water column properties common to shallow-water environments and their impact on inversion results. Advances made in t...

Variability in seabed properties represents a major concern for safe and efficient travel across tidal flats. Especially problematic are “oozing mudflats” (cf. Wells, 1983, Frey et al., 1989) with high porosity and low strength. People and equipment can sink deeply into such muds, making travel difficult and potentially dangerous. The link between seabed properties and “trafficability” motivate...

In this article we present numerical studies of waves interacting with a cylindrical point absorber that is directly driving a seabed based linear generator. For waves useful for power conversion, the wave/point absorber interaction can be modelled, using potential theory assuming an inviscid irrotational incompressible fluid. The generator is modelled as a viscous damper. This paper pays speci...

The acoustic methods as a non-invasive and teledetective are very good tools to study the stratification of bottom sediments, particularly useful as a research tool is a parametric sonar, which works together with other acoustic devices used for underwater observation, such as multibeam sonars and side scan sonars. Using the techniques of synthetic apparatus they can provide relatively a lot of...

When the gas hydrates dissociate, the mechanical properties of sediments will change, which may cause the deformation of the seabed. Such incidence will directly affect the stability of the undersea device. Under the consideration of seepage-stress coupling, this paper analyzed the deformation of seabed using finite element method. Duncan Chang’s E-B constitutive model code was written, the imp...

This paper shows that under the assumption of the out-going radiation conditions at infinity, the time-harmonic acoustic scattered field off a sound-soft solid in a shallow ocean with a fluid-like seabed is unique in C2 M1 C2 M2 C Rh Ω . Here M1 is the water part, M2 the seabed, Rh the waveguide and Ω the solid object. The associated modal problem is studied and a representation formula for the...