Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

Performance prediction of hydrofoil- supported catamarans using experiment and ANNs

https://repository.tudelft.nl/islandora/object/uuid%3A88850a46-84ac-441b-b073-5fc9530cf9c0/datastream/OBJ/download

Hydrodynamics of single-deadrise hulls and their catamaran configurations

Aerodynamic support is beneficial for achieving very high speeds of marine transportation. Wing-in-ground vehicles, power-augmented ram platforms, and ultrafast planing multihulls are examples of marine craft with air assistance. The main technical problems in the development and application of these concepts for marine transportation are to ensure motion stability and to provide adequate seaworthiness. In this article, the authors illustrate applications of several mathematical models for various air-supported marine vehicle concepts and discuss their specific stability issues. The aerodynamic submodels are based on nonlinear vortex-lattice methods and on the extreme ground effect theory, whereas unsteady hydrodynamics of planing surfaces are treated with added-mass strip theories. The static and dynamic stability in the vicinity of equilibrium states can be analyzed by linearized approaches. However, motions in transient regimes and unsteady environments require implementation of nonlinear and fully unsteady modeling methods.

Dynamics and Stability of Boats With Aerodynamic Support

This work is concerned with the hydrodynamic design of hydrofoil-assisted catamarans. Focus is placed on the development of new and suitable design methods and application of these to identify the most important geometric parameters of catamaran hulls and hydrofoil configurations that influence efficiency and performance. These goals are pursued by firstly gaining a thorough understanding of the governing hydrodynamic principles involved in the design process. This knowledge is then applied to develop new and improved experimental techniques and theoretical methods needed for design. Both are improved to the extent where they can be applied as design tools covering the important semi-displacement and semi-planing speeds, which are the focus of this study. The operational speed range of hydrofoil-assisted catamarans is shown to consist of three distinct hydrodynamic phases (displacement, transition and planing) and that different hydrodynamic principles govern vessel performance in each phase. The hydrodynamics are found to differ substantially from that of conventional high-speed craft, primarily due to the interaction between the hull and the hydrofoils, which is found to vary with speed and results in the need for more complex experimental procedures to be followed if accurate predictions of resistance are to be made. Experimental predictions based on scaled model tests of relatively small hydrofoilassisted catamaran models are found to be less accurate than that achievable for conventional ships because of the inability to correct for all scaling errors encountered during model testing. With larger models scaling errors are encountered to a lesser degree. The most important scale effect is found to be due to the lower Reynolds number of the flow over the scaled foils. The lower Reynolds number results in higher drag and lower lift coefficients for hydrofoils compared with those achieved at full scale. This effect can only be partially corrected for in the scaling procedure using the available theoretical scaling methods. Presently available theoretical methods commonly used for the design of conventional ships were found to be ill adapted for modeling the complex hydrodynamics of hydrofoil-assisted catamarans and required further development. Vortex lattice theory was chosen to model the flow around hydrofoil-assisted catamarans as vortex theory models the flow around lifting surfaces in the most natural way. The commercial code AUTOWING is further developed and generalized to be able to model the complex hull-hydrofoil interactions that change with speed. The method is shown to make good predictions of all hydrodynamic quantities with accuracies at least as good as that achievable through model testing and therefore fulfills the requirements for a suitable theoretical design tool. Stellenbosch University http://scholar.sun.ac.za

Design and optimization of hydrofoil-assisted catamarans

The aim of this paper is to derive a mathematical model for predicting the longitudinal stability of racing boats with aerodynamic support. The theory is based on a combination of stability theories developed for planing boats and wing in ground effect craft. The influence of different geometric and mass boat parameters on the stability is investigated.

/pdf/dynamics-and-stability-of-racing-boats-with-air-wings-1q0mgueg5j.pdf

Dynamics and stability of racing boats with air wings

A catamaran (10) has two spaced demihulls (12) which are connected by an upper superstructure above the waterline. The catamaran (10) includes a main hydrofoil (26) extending between the demihulls at keel level slightly forward of the longitudinal centre of gravity LCG (22) of the catamaran. Each demihull (12) defines an aft swept step formation (28) located slightly forward of the LCG (22) and extending transversely relative to a longitudinal centre line CL defined between the demihulls. Each step formation (28) defines a step extending along a straight line and having a height dimension which tapers from an inner position at the keel (18) of the hull towards an outer position at the chine (20) of the hull. Each demihull defines a planing region immediately in front of the step formation (28), which has a concave hydrodynamic profile configured to generate lift on a wetted area of the hull.

A hydrofoil-assisted multi-hulled watercraft

Development of hydrofoil supported catamarans with semi-displacement hulls

Extensive experimental investigations of hydrofoil-assisted catamarans have identified the main hydrodynamic parameters affecting the performance of these vessels. Design principles of existing vessels are discussed in the light of these hydrodynamic findings. The experience gained from experimental testing has provided the basis for the development of a non-linear vortex lattice method for design purposes. The method is validated by comparison with experimental results and applied to the problem of optimizing a 40-knot, 40m hydrofoil-assisted catamaran with a hydrofoil system developed for modern high-speed catamarans. It is shown that the method can be successfully applied to optimization problems of these vessels as it successfully captures the complex hull-foil interactions. Results of the numerical investigation performed, indicate that optimizing the mutual distance between the hydrofoils can significantly improve the lift to drag ratio of such a vessel.

Gunther Migeotte

Papers

Design and optimization of hydrofoil-assisted catamarans

Dynamics and stability of racing boats with air wings

A hydrofoil-assisted multi-hulled watercraft

Development of hydrofoil supported catamarans with semi-displacement hulls

Design of hydrofoil assisted catamarans using a non-linear vortex lattice method