The application of computational fluid dynamics to the modelling and design of high-speed boats

Computational fluid dynamics solvers were applied to the field of high-speed boat design. The lattice Boltzmann method was used to assess the water-phase of the flow around a number of high-speed hullform geometries, and was validated against empirical industry and literature data. A heave dynamics capability was developed to assess the heave equilibrium position of a high speed boat, showing close agreement with industry data. A mesh movement and evolutionary optimisation software was applied to the aero-dynamic optimisation of a high-speed catamaran using a Reynolds-averaged Navier-Stokes solver for modelling of the air phase of the flow

Aeronautical Engineering: A special bibliography with indexes, supplement 74

This special bibliography lists 295 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1976

Tunnel Engineering

This volume presents a selection of chapters covering a wide range of tunneling engineering topics. The scope was to present reviews of established methods and new approaches in construction practice and in digital technology tools like building information modeling. The book is divided in four sections dealing with geological aspects of tunneling, analysis and design, new challenges in tunnel construction, and tunneling in the digital era. Topics from site investigation and rock mass failure mechanisms, analysis and design approaches, and innovations in tunnel construction through digital tools are covered in 10 chapters. The references provided will be useful for further reading

Cavity flow over a wall-mounted fence

Ventilated cavity flow over a wall mounted fence is experimentally investigated in a cavitation tunnel. The flow over a 2-D fence, attached to the tunnel test section ceiling, is examined for a range of free-stream conditions. The dependence of cavity topology, cavitation number, upstream wall pressure distribution and drag on several parameters, including ventilation rate, fence height based Froude number (Fr), vapour pressure based cavitation number (σv ) and degree of fence immersion in the oncoming wall boundary layer, is investigated. Three different flow regimes are identified throughout the range of cavitation numbers for a particular set of free-stream conditions: shear layer cavitation, fully developed cavity and ‘blocked’ flow. The cavity exhibits a typical re-entrant jet closure and the re-entrant jet intensity is found to be a function of Fr. The high intensity re-entrant jet, present at high Fr, leads to an increase in drag. Drag decreases significantly with an increase in fence immersion in the oncoming boundary layer. Complementary measurements for a naturally cavitating flow are obtained for comparison. A more detailed examination of the topology and unsteady behaviour of ventilated and natural cavity flows over a 2-D wall-mounted fence was undertaken for fixed length cavities with varying free-stream velocity using high-speed and still imaging, X-ray densitometry and dynamic surface pressure measurements in two experimental facilities. Two main unsteady features are observed, the irregular small-scale shedding of structures at the cavity closure and a larger-scale re-entrant jet oscillation. Small-scale cavity break-up was associated with a high-frequency broad-band peak in the wall pressure spectra, found to be governed by the overlying turbulent boundary layer characteristics, similar to observations from single-phase flow over a forward-facing step. A low-frequency peak reflecting the oscillations in size of re-entrant jet, analogous to the ‘flapping’ motion in single-phase flow, was found to be modulated by gravity effects (i.e. a Froude number dependency). Likewise, a significant change in cavity behaviour was observed as the flow underwent transition analogous to the transition from sub- to super- critical regime in open-channel flow. A companion numerical study is undertaken to provide additional insight into particular flow features such as the separated flow region upstream of the fence and to assess the influence of blockage. An implicit unsteady compressible solver is used with a RANS k − ω SST turbulence model and VOF approach to capture the cavity interface. The numerical results are found to compare reasonably with the experimental data, additionally showing a significant influence of blockage on the studied flow. Along with the 2-D fence, a 3-D wall mounted fence, spanning nominally a quarter of the tunnel test section, is investigated. The impact that 3-D effects have on the cavity topology and the relations between the parameters characterizing the flow is observed. The most notable effect of 3-D flow is a change in the closure mechanism observed for low Fr. Following a decrease in Fr the closure topology transforms from a well defined single re-entrant jet regime, through a phase of gradual re-entrant jet widening to a completely split re-entrant jet separated into two branches. Generally, the 2-D and 3-D flows exhibited similar trends with any significant difference attributable to differing levels of flow confinement due to lesser width of 3-D fence

Advanced Computational Fluid Dynamics for Emerging Engineering Processes

As researchers deal with processes and phenomena that are geometrically complex and phenomenologically coupled the demand for high-performance computational fluid dynamics (CFD) increases continuously. The intrinsic nature of coupled irreversibility requires computational tools that can provide physically meaningful results within a reasonable time. This book collects the state-of-the-art CFD research activities and future R&D directions of advanced fluid dynamics. Topics covered include in-depth fundamentals of the Navier-Stokes equation, advanced multi-phase fluid flow, and coupling algorithms of computational fluid and particle dynamics. In the near future, true multi-physics and multi-scale simulation tools must be developed by combining micro-hydrodynamics, fluid dynamics, and chemical reactions within an umbrella of irreversible statistical physics

Magnetic Suspension and Balance Systems: A Comprehensive, Annotated Bibliography

This bibliography contains 301 entries. Results are reported of recent studies aimed at increasing the research capabilities of magnetic suspension and balance systems; e.g., increasing force and torque capability, increasing angle of attack capability, and increasing overall system reliability. The problem is addressed of scaling from the relatively small size of existing systems to much larger sizes. The purpose of the bibliography is to provide an up-to-date list of publications that might be helpful to persons interested in magnetic suspension and balance systems for use in wind tunnels. The arrangement is generally chronological by date of presentation. However, papers presented at conferences or meetings are placed under dates of presentation. The numbers assigned to many of the citations have been changed from those used in the previous bibliography. This has been done in order to allow outdated citations to be removed and some recently discovered older works to be included in their proper chronological order. Author, source, and subject indexes are included in order to increase the usefulness of this compilation