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Mathematical Models in coastal engineering
cussing the various processes or mechanisms has been first to describe it and then to account for it theoretically. The text is not exhaustive but tries to present a reasonable balance of the fundamentals. C h a p t e r one provides an overview of physical oceanography; succeeding chapter are: Forcing Functions and Responses, tlydrodynamic Equations of the Sea, T h e r m o d y namics and Energy Relations, Geophysical Fluid Dynamics I Waves and Tides, II Currents and Circulation - Accoustical Oceanography, Electromagnetics and the Sea, and Optics of the Sea. The book is completed by five appendices of physical constants, parameters and dimensionless numbers and an appendix.
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Lance Sucharov Gomputational Mechanics Publications Southampton, UK
proposed these could be reduced o r even eliminated by a gradual reduction in magnetising current since, as demonstrated by the analytical work, magnetic particle attraction by crack-like defects is considerably stronger than that associated with corners, being in the proportion of the square of the distance from the source of the disturbance in the field. T h e figures are well presented and comprehensive. The text is also well presented but suffers badly in parts from editorial lapses. Nevertheless, the report will be useful to those concerned with the subtleties of MPI inspections on welded plates and possibly joints.
Paul A. Frieze Underwater NDE Centre University College London, UK
Metallurgical Conditions Affecting tile Reliability of Magnetic Particle Inspection Offshore
Mathematical
Technology Report OTH 87-275
Pentech Press, London, 1988
HMSO, 1987, ISBN 0 110412 888 X, s
82 pages
Tills report seems to provide a useful review of the basic magnetic properties of steel commonly used in offshore construction and the various features affecting permeability. These features are considered from the viewpoint of how their influences may affect the ability to execute MPI inspection to the relevant standards (BS6072:1981 and PD513: 1985). T h e main features examined are weldments, heat-affected zones, post-weld heat treatment, elastic straining and plastic straining in Grade 50 D material; and incorrect heat t r e a t m e n t and lack of tempering in R Q T 501 and 701 steels. Raw d a t a in the form of flux-field strength loops are presented for a number of cases, measurements having been obtained form rectangular specimens cut from welded a n d / o r treated plate and fitted with an uncompensated double yoke permameter. Two-dimensional analytical solutions are then generated for the cases of a surface breaking crack, an interface between zones o f different permeability, a strip of contrasting permeability, and a corner (weld toe). The results from these are used to interpret the permeability measurements on a combined theoretical-experimental basis. Some of the conclusions are useful in supporting the present BS6072 guidance for MPI inspection although any application to the complex joint shapes encountered in offshore structures needs to be carefully considered. A t field strengths greater than approximately 12 Oersted, field strength is by far the most i m p o r t a n t controlling parameter. Below this strength, material properties as affected by welding and the heat associated therewith are of equal importance. Tile ease with which the BS6072 minimum flux density of 0.72 Tesla can be achieved with the generally recommended 30 Oersted field strength is concluded to generate a number of spurious indications at weld toes and similar. It is
52
Models in Coastal Engineering
C.G. Koutitas
Applied Ocean Research, 1990, VoL12, No. 1
The objective of this book is to provide a basic methodology for the formulation and numerical solution of mathematical models in coastal engineering. It is divided into four chapters covering the following topics: 1. Mathematical theory of waves: small- and finite-amplitude waves; short and long waves; reflection, refraction, shoaling, breaking and energy dissipation due to bed friction; statistical properties of wind generated waves.
2. Mathematical models of coastal circulation: tidal models; wind and wave generated circulation; stratified flow. 3. Transport of pollutants in coastal regions: turbulent advection-diffusion; numerical solution algorithms. 4. Matematical models for sediment transport in coastal areas: the sediment budget equation; bed and suspended sediment loads; bed morphology models. Many worked illustrative examples of practical coastal engineering problems are included, with the corresponding computer program listing in BASIC. Whenever a numerical method of solution is necessary, the author makes use of standard finite difference techniques. The author claims that "the book will enable engineering consultants, researchers and postgraduate students in coastal engineering and oceanography to apply the sophisticated techniques used in m a j o r coastal engineering works to small scale design using microcomputers", but this statement should be considered exaggerated. The book is very appropriate for final year undergraduate or M.Sc. courses but engineering consultants and researchers will find the techniques and programs too simplified for real-life, complex nonlinear problems.
-
Lance Sucharov Gomputational Mechanics Publications Southampton, UK
proposed these could be reduced o r even eliminated by a gradual reduction in magnetising current since, as demonstrated by the analytical work, magnetic particle attraction by crack-like defects is considerably stronger than that associated with corners, being in the proportion of the square of the distance from the source of the disturbance in the field. T h e figures are well presented and comprehensive. The text is also well presented but suffers badly in parts from editorial lapses. Nevertheless, the report will be useful to those concerned with the subtleties of MPI inspections on welded plates and possibly joints.
Paul A. Frieze Underwater NDE Centre University College London, UK
Metallurgical Conditions Affecting tile Reliability of Magnetic Particle Inspection Offshore
Mathematical
Technology Report OTH 87-275
Pentech Press, London, 1988
HMSO, 1987, ISBN 0 110412 888 X, s
82 pages
Tills report seems to provide a useful review of the basic magnetic properties of steel commonly used in offshore construction and the various features affecting permeability. These features are considered from the viewpoint of how their influences may affect the ability to execute MPI inspection to the relevant standards (BS6072:1981 and PD513: 1985). T h e main features examined are weldments, heat-affected zones, post-weld heat treatment, elastic straining and plastic straining in Grade 50 D material; and incorrect heat t r e a t m e n t and lack of tempering in R Q T 501 and 701 steels. Raw d a t a in the form of flux-field strength loops are presented for a number of cases, measurements having been obtained form rectangular specimens cut from welded a n d / o r treated plate and fitted with an uncompensated double yoke permameter. Two-dimensional analytical solutions are then generated for the cases of a surface breaking crack, an interface between zones o f different permeability, a strip of contrasting permeability, and a corner (weld toe). The results from these are used to interpret the permeability measurements on a combined theoretical-experimental basis. Some of the conclusions are useful in supporting the present BS6072 guidance for MPI inspection although any application to the complex joint shapes encountered in offshore structures needs to be carefully considered. A t field strengths greater than approximately 12 Oersted, field strength is by far the most i m p o r t a n t controlling parameter. Below this strength, material properties as affected by welding and the heat associated therewith are of equal importance. Tile ease with which the BS6072 minimum flux density of 0.72 Tesla can be achieved with the generally recommended 30 Oersted field strength is concluded to generate a number of spurious indications at weld toes and similar. It is
52
Models in Coastal Engineering
C.G. Koutitas
Applied Ocean Research, 1990, VoL12, No. 1
The objective of this book is to provide a basic methodology for the formulation and numerical solution of mathematical models in coastal engineering. It is divided into four chapters covering the following topics: 1. Mathematical theory of waves: small- and finite-amplitude waves; short and long waves; reflection, refraction, shoaling, breaking and energy dissipation due to bed friction; statistical properties of wind generated waves.
2. Mathematical models of coastal circulation: tidal models; wind and wave generated circulation; stratified flow. 3. Transport of pollutants in coastal regions: turbulent advection-diffusion; numerical solution algorithms. 4. Matematical models for sediment transport in coastal areas: the sediment budget equation; bed and suspended sediment loads; bed morphology models. Many worked illustrative examples of practical coastal engineering problems are included, with the corresponding computer program listing in BASIC. Whenever a numerical method of solution is necessary, the author makes use of standard finite difference techniques. The author claims that "the book will enable engineering consultants, researchers and postgraduate students in coastal engineering and oceanography to apply the sophisticated techniques used in m a j o r coastal engineering works to small scale design using microcomputers", but this statement should be considered exaggerated. The book is very appropriate for final year undergraduate or M.Sc. courses but engineering consultants and researchers will find the techniques and programs too simplified for real-life, complex nonlinear problems.